WorldWideScience

Sample records for fired entrained flow

  1. Entrained Flow Reactor Test of Potassium Capture by Kaolin

    DEFF Research Database (Denmark)

    Wang, Guoliang; Jensen, Peter Arendt; Wu, Hao

    2015-01-01

    In the present study a method to simulate the reaction between gaseous KCl and kaolin at suspension fired condition was developed using a pilot-scale entrained flow reactor (EFR). Kaolin was injected into the EFR for primary test of this method. By adding kaolin, KCl can effectively be captured...

  2. Entrained Flow Gasification of Biomass

    DEFF Research Database (Denmark)

    Qin, Ke

    The present Ph. D. thesis describes experimental and modeling investigations on entrained flow gasification of biomass and an experimental investigation on entrained flow cogasification of biomass and coal. A review of the current knowledge of biomass entrained flow gasification is presented....... Biomass gasification experiments were performed in a laboratory-scale atmospheric pressure entrained flow reactor with the aim to investigate the effects of operating parameters and biomass types on syngas products. A wide range of operating parameters was involved: reactor temperature, steam/carbon ratio......, excess air ratio, oxygen concentration, feeder gas flow, and residence time. Wood, straw, and lignin were used as biomass fuels. In general, the carbon conversion was higher than 90 % in the biomass gasification experiments conducted at high temperatures (> 1200 °C). The biomass carbon...

  3. Entrainment in vertical annular two-phase flow

    International Nuclear Information System (INIS)

    Sawant, Pravin; Ishii, Mamoru; Mori, Michitsugu

    2009-01-01

    Prediction of amount of entrained droplets or entrainment fraction in annular two-phase flow is essential for the estimation of dryout condition and analysis of post dryout heat transfer in light water nuclear reactors and steam boilers. In this study, air-water and organic fluid (Freon-113) annular flow entrainment experiments have been carried out in 9.4 and 10.2 mm diameter test sections, respectively. Both the experiments covered three distinct pressure conditions and wide range of liquid and gas flow conditions. The organic fluid experiments simulated high pressure steam-water annular flow conditions. In each of the experiments, measurements of entrainment fraction, droplet entrainment rate and droplet deposition rate have been performed by using a liquid film extraction method. A simple, explicit and non-dimensional correlation developed by Sawant et al. (2008a) for the prediction of entrainment fraction is further improved in this study in order to account for the existence of critical gas and liquid flow rates below which no entrainment is possible. Additionally, a new correlation is proposed for the estimation of minimum liquid film flow rate at the maximum entrainment fraction condition. The improved correlation successfully predicted the newly collected air-water and Freon-113 entrainment fraction data. Furthermore, the correlations satisfactorily compared with the air-water, helium-water and air-genklene experimental data measured by Willetts (1987). (author)

  4. Oxy-coal combustion in an entrained flow reactor: Application of specific char and volatile combustion and radiation models for oxy-firing conditions

    DEFF Research Database (Denmark)

    Álvarez, L.; Yin, Chungen; Riaza, J.

    2013-01-01

    The deployment of oxy-fuel combustion in utility boilers is one of the major options for CO2 capture. However, combustion under oxy-firing conditions differs from conventional air-firing combustion, e.g., in the aspect of radiative heat transfer, coal conversion and pollutants formation....... In this work, a numerical study on pulverised coal combustion was conducted to verify the applicability and accuracy of several sub-models refined for oxy-fuel conditions, e.g., gaseous radiative property model, gas-phase combustion mechanism and heterogeneous char reaction model. The sub-models were...... implemented in CFD (Computational Fluid Dynamics) simulations of combustion of three coals under air-firing and various oxy-firing (21-35% vol O2 in O2/CO2 mixture) conditions in an EFR (entrained flow reactor). The predicted coal burnouts and gaseous emissions were compared against experimental results...

  5. STUDY OF MERCURY OXIDATION BY SCR CATALYST IN AN ENTRAINED-FLOW REACTOR UNDER SIMULATED PRB CONDITIONS

    Science.gov (United States)

    A bench-scale entrained-flow reactor system was constructed for studying elemental mercury oxidation under selective catalytic reduction (SCR) reaction conditions. Simulated flue gas was doped with fly ash collected from a subbituminous Powder River Basin (PRB) coal-fired boiler ...

  6. A droplet entrainment model for horizontal segregated flows

    Energy Technology Data Exchange (ETDEWEB)

    Höhne, Thomas, E-mail: T.Hoehne@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf (HZDR) – Institute of Fluid Dynamics, P.O. Box 510119, D-01314 Dresden (Germany); Hänsch, Susann [Imperial College, Department of Mechanical Engineering, South Kensington Campus, London SW7 2AZ (United Kingdom)

    2015-05-15

    Highlights: • We further developed the flow morphology detection model AIAD. • An advanced droplet entrainment model was introduced. • The new approach is applied against HAWAC experiments. - Abstract: One limitation in simulating horizontal segregated flows is that there is no treatment of droplet formation mechanisms at wavy surfaces. For self-generating waves and slugs, the interfacial momentum exchange and the turbulence parameters have to be modeled correctly. Furthermore, understanding the mechanism of droplet entrainment for heat and mass transfer processes is of great importance in the chemical and nuclear industry. The development of general computational fluid dynamics models is an essential precondition for the application of CFD codes to the modeling of flow related phenomena. The new formulation for the interfacial drag at the free surface and turbulence parameters within the algebraic interfacial area density model (AIAD) represents one step toward a more physical description of free surface flows including less empiricism. The AIAD approach allows the use of different physical models depending on the local fluid morphology inside a macro-scale multi-fluid framework. A further step of improving the modeling of free interfaces lies within the consideration of droplet entrainment mechanisms. In this paper a new sub-grid entrainment model is proposed, which assumes that due to liquid turbulence the interface gets rough and wavy leading to the formation of droplets. Therefore, the droplet entrainment model requires the consideration of an additional droplet phase, which is described with an own set of balance equations in the spirit of the particle model. Two local key factors determine the rate of droplet entrainment: the liquid turbulent kinetic energy as well as the outward velocity gradient of the liquid relative to the interface motion. The new droplet entrainment approach is included into CFD simulations for attempting to reproduce existing

  7. K-capture by Al-Si based Additives in an Entrained Flow Reactor

    DEFF Research Database (Denmark)

    Wang, Guoliang; Jensen, Peter Arendt; Wu, Hao

    2016-01-01

    A water slurry, consisting of KCl and Al-Si based additives (kaolin and coal fly ash) was fed into an entrained flow reactor (EFR) to study the K-capturing reaction of the additives at suspension-fired conditions. Solid products collected from the reactor were analysed with respect to total...... of KCl to K-aluminosilicate decreased. When reaction temperature increased from 1100 °C to 1450 °C, the conversion of KCl does not change significantly, which differs from the trend observed in fixed-bed reactor....

  8. Dryout-type critical heat flux in vertical upward annular flow: effects of entrainment rate, initial entrained fraction and diameter

    Science.gov (United States)

    Wu, Zan; Wadekar, Vishwas; Wang, Chenglong; Sunden, Bengt

    2018-01-01

    This study aims to reveal the effects of liquid entrainment, initial entrained fraction and tube diameter on liquid film dryout in vertical upward annular flow for flow boiling. Entrainment and deposition rates of droplets were included in mass conservation equations to estimate the local liquid film mass flux in annular flow, and the critical vapor quality at dryout conditions. Different entrainment rate correlations were evaluated using flow boiling data of water and organic liquids including n-pentane, iso-octane and R134a. Effect of the initial entrained fraction (IEF) at the churn-to-annular flow transition was also investigated. A transitional Boiling number was proposed to separate the IEF-sensitive region at high Boiling numbers and the IEF-insensitive region at low Boiling numbers. Besides, the diameter effect on dryout vapor quality was studied. The dryout vapor quality increases with decreasing tube diameter. It needs to be pointed out that the dryout characteristics of submillimeter channels might be different because of different mechanisms of dryout, i.e., drying of liquid film underneath long vapor slugs and flow boiling instabilities.

  9. Investigations of bi-directional flow behaviour in presence of a large vertical opening in a fire compartment

    International Nuclear Information System (INIS)

    Sharma, Pavan K.; Gera, B.

    2011-01-01

    In the complex thermal hydraulics codes developed for fire, reactor and containment safety the junctions in the multi-compartment geometries are often modeled as uni-directional junctions and some construct of flow coefficient. However, certain large size junctions are known to depict bi-directional flow behaviour under specific circumstances. The CFD based computer code FDS was used for an earlier reported study of fire in an enclosure on the bidirectional flow behaviour in present of a wall opening. Numerical simulation is directed to monitor the entrainment of the fresh air from outside to the fire compartment and resulting plume deflection due to presence of a big opening. The paper presents the details of the analysis, the results obtained, and comparison with the reported experimental data in terms of plume deflection, entrainment. Detailed investigations have been carried out to understand the bi-directionality of a junction by analyzing studying the outgoing hot air flow and incoming cold air. (orig.)

  10. Elementary theory of bed-sediment entrainment by debris flows and avalanches

    Science.gov (United States)

    Iverson, Richard M.

    2012-01-01

    Analyses of mass and momentum exchange between a debris flow or avalanche and an underlying sediment layer aid interpretations and predictions of bed-sediment entrainment rates. A preliminary analysis assesses the behavior of a Coulomb slide block that entrains bed material as it descends a uniform slope. The analysis demonstrates that the block's momentum can grow unstably, even in the presence of limited entrainment efficiency. A more-detailed, depth-integrated continuum analysis of interacting, deformable bodies identifies mechanical controls on entrainment efficiency, and shows that entrainment rates satisfy a jump condition that involves shear-traction and velocity discontinuities at the flow-bed boundary. Explicit predictions of the entrainment rateEresult from making reasonable assumptions about flow velocity profiles and boundary shear tractions. For Coulomb-friction tractions, predicted entrainment rates are sensitive to pore fluid pressures that develop in bed sediment as it is overridden. In the simplest scenario the bed sediment liquefies completely, and the entrainment-rate equation reduces toE = 2μ1gh1 cos θ(1 − λ1)/ , where θ is the slope angle, μ1 is the flow's Coulomb friction coefficient, h1 is its thickness, λ1 is its degree of liquefaction, and is its depth-averaged velocity. For values ofλ1ranging from 0.5 to 0.8, this equation predicts entrainment rates consistent with rates of 0.05 to 0.1 m/s measured in large-scale debris-flow experiments in which wet sediment beds liquefied almost completely. The propensity for bed liquefaction depends on several factors, including sediment porosity, permeability, and thickness, and rates of compression and shear deformation that occur when beds are overridden.

  11. Performance of entrained flow and fluidised bed biomass gasifiers on different scales

    International Nuclear Information System (INIS)

    Tremel, Alexander; Becherer, Dominik; Fendt, Sebastian; Gaderer, Matthias; Spliethoff, Hartmut

    2013-01-01

    Highlights: ► Gasification of biomass in fluidised bed and entrained flow reactors is modelled. ► The systems are evaluated for a thermal input from 10 MW to 500 MW. ► Special attention is given to the preconditioning methods for biomass. ► Fluidised bed and entrained flow gasifiers are compared in terms of efficiency and costs. - Abstract: This biomass gasification process study compares the energetic and economic efficiencies of a dual fluidised bed and an oxygen-blown entrained flow gasifier from 10 MW th to 500 MW th . While fluidised bed gasification became the most applied technology for biomass in small and medium scale facilities, entrained flow gasification technology is still used exclusively for industrial scale coal gasification. Therefore, it is analysed whether and for which capacity the entrained flow technology is an energetically and economically efficient option for the thermo-chemical conversion of biomass. Special attention is given to the pre-conditioning methods for biomass to enable the application in an entrained flow gasifier. Process chains are selected for the two gasifier types and subsequently transformed to simulation models. The simulation results show that the performance of both gasifier types is similar for the production of a pressurised product gas (2.5 MPa). The cold gas efficiency of the fluidised bed is 76–79% and about 0.5–2 percentage points higher than for the entrained flow reactor. The net efficiencies of both technologies are similar and between 64% and 71% depending on scale. The auxiliary power consumption of the entrained flow reactor is caused mainly by the air separation unit, the oxygen compression, and the fuel pulverisation, whereas the fluidised bed requires additional power mainly for gas compression. The costs for the product gas are determined as between €4.2 cent/kWh (500 MW th ) and €7.4 cent/kWh (10 MW th ) in the economic analysis of both technologies. The study indicates that the

  12. Sulfate reduction in an entrained-flow black liquor gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Kymaelaeinen, M.; Janka, K. [Tampella Power, Tampere (Finland); Frederick, W.J.; Littau, M.; Sricharoenchaikul, V.; Jivakanun, N.; Waag, K. [Oregon State Univ., Corvallis, OR (United States). Dept. of Chemical Engineering

    1995-12-31

    Sulfate reduction and carbon conversion during pyrolysis and gasification of black liquor particles were experimentally studied in a laminar entrained-flow reactor. A model was also developed to simulate an entrained-flow black liquor gasifier. Experimental results were then compared to model calculations. Results indicated that carbon must be present to get a high degree of sulfate reduction during gasification. It is therefore important to balance the rates of carbon conversion and sulfate reduction. High local temperatures in the reactor should be avoided so that carbon does not convert too rapidly, but temperatures of nearly 1000 degrees C are required to achieve good sulfate reduction. It was suggested that a new equation was needed to adequately predict sulfate reduction in an entrained-flow black liquor gasifier. 12 refs., 8 figs., 5 tabs.

  13. Review Article: Advances in modeling of bed particle entrainment sheared by turbulent flow

    Science.gov (United States)

    Dey, Subhasish; Ali, Sk Zeeshan

    2018-06-01

    Bed particle entrainment by turbulent wall-shear flow is a key topic of interest in hydrodynamics because it plays a major role to govern the planetary morphodynamics. In this paper, the state-of-the-art review of the essential mechanisms governing the bed particle entrainment by turbulent wall-shear flow and their mathematical modeling is presented. The paper starts with the appraisal of the earlier multifaceted ideas in modeling the particle entrainment highlighting the rolling, sliding, and lifting modes of entrainment. Then, various modeling approaches of bed particle entrainment, such as deterministic, stochastic, and spatiotemporal approaches, are critically analyzed. The modeling criteria of particle entrainment are distinguished for hydraulically smooth, transitional, and rough flow regimes. In this context, the responses of particle size, particle exposure, and packing condition to the near-bed turbulent flow that shears the particles to entrain are discussed. From the modern experimental outcomes, the conceptual mechanism of particle entrainment from the viewpoint of near-bed turbulent coherent structures is delineated. As the latest advancement of the subject, the paper sheds light on the origin of the primitive empirical formulations of bed particle entrainment deriving the scaling laws of threshold flow velocity of bed particle motion from the perspective of the phenomenological theory of turbulence. Besides, a model framework that provides a new look on the bed particle entrainment phenomenon stemming from the stochastic-cum-spatiotemporal approach is introduced. Finally, the future scope of research is articulated with open questions.

  14. De-entrainment on vertical elements in air droplet cross flow

    International Nuclear Information System (INIS)

    Dallman, J.C.; Kirchner, W.L.

    1980-01-01

    De-entrainment phenomena on vertical elements in air-water droplet cross flow are generated using a horizontal array of water spray nozzles and a draft-induced wind tunnel. These conditions are used to obtain experimental values of the de-entrainment efficiency of isolated elements (25.4-, 63.5-, and 101.6-mm-diam cylinders and a 76.2-mm-square tube), and of an array of 101.6-mm-diam cylinders. A flow model is developed that extrapolates the de-entrainment efficiency of isolated elements through the use of a correlation for the interference effect to predict the efficiency of large arrays of similar elements. This simple model is shown to provide a good prediction of the de-entrainment efficiency of arrays in terms of the efficiency of an isolated element

  15. Mixing and entrainment in hydraulically driven stratified sill flows

    DEFF Research Database (Denmark)

    Nielsen, Morten Holtegaard; Pratt, Larry; Helfrich, Karl

    2004-01-01

    The investigation involves the hydraulic behaviour of a dense layer of fluid flowing over an obstacle and subject to entrainment of mass and momentum from a dynamically inactive (but possibly moving) overlying fluid. An approach based on the use of reduced gravity, shallow-water theory with a cross......-interface entrainment velocity is compared with numerical simulations based on a model with continuously varying stratification and velocity. The locations of critical flow (hydraulic control) in the continuous model are estimated by observing the direction of propagation of small-amplitude long-wave disturbances...... that the reduced gravity model systematically underestimates inertia and overestimates buoyancy. These differences are quantified by shape coefficients that measure the vertical non-uniformities of the density and horizontal velocity that arise, in part, by incomplete mixing of entrained mass and momentum over...

  16. Entrainment at a sediment concentration interface in turbulent channel flow

    Science.gov (United States)

    Salinas, Jorge; Shringarpure, Mrugesh; Cantero, Mariano; Balachandar, S.

    2016-11-01

    In this work we address the role of turbulence on entrainment at a sediment concentration interface. This process can be conceived as the entrainment of sediment-free fluid into the bottom sediment-laden flow, or alternatively, as the entrainment of sediment into the top sediment-free flow. We have performed direct numerical simulations for fixed Reynolds and Schmidt numbers while varying the values of Richardson number and particle settling velocity. The analysis performed shows that the ability of the flow to pick up a given sediment size decreases with the distance from the bottom, and thus only fine enough sediment particles are entrained across the sediment concentration interface. For these cases, the concentration profiles evolve to a final steady state in good agreement with the well-known Rouse profile. The approach towards the Rouse profile happens through a transient self-similar state. Detailed analysis of the three dimensional structure of the sediment concentration interface shows the mechanisms by which sediment particles are lifted up by tongues of sediment-laden fluid with positive correlation between vertical velocity and sediment concentration. Finally, the mixing ability of the flow is addressed by monitoring the center of mass of the sediment-laden layer. With the support of ExxonMobil, NSF, ANPCyT, CONICET.

  17. Entrainment and deposition rates of droplets in annular two-phase flow

    International Nuclear Information System (INIS)

    Kataoka, I.; Ishii, M.

    1986-01-01

    The droplet entrainment from a liquid film is important to the mass, momentum, and energy transfer process in annular two-phase flow. For example, the amount of entrainment as well as the rate of entrainment significantly affect the occurrences of the dryout, whereas the post-CHF heat transfer depends strongly on the entrainment and droplet sizes. Despite the importance of the entrainment rate, there have been no satisfactory correlations available in the literature. In view of these, correlations for entrainment rate covering both entrance region and equilibrium region were developed from a simple model in collaboration with data. Results show that the entrainment rate varies considerably in the entrainment-development region. However, at a certain distance from an inlet it attains an equilibrium value. A simple approximate correlation was obtained for the equilibrium state where entrainment rate and deposition rate becomes equal. The result indicates that the equilibrium entrainment rate is proportional to Weber number based on the hydraulic diameter of a tube. 34 references, 14 figures

  18. Droplet behavior analysis in consideration of droplet entrainment from liquid film in annular dispersed flow

    International Nuclear Information System (INIS)

    Matsuura, Keizo; Otake, Hiroshi; Kataoka, Isao; Serizawa, Akimi

    2000-01-01

    A method of droplet behavior simulation in an annular dispersed flow has been developed. In this method, both droplet deposition and entrainment from liquid film are considered. The Lagrangian method and stochastic model are used to analyze droplet diffusion and deposition behavior in a turbulent flow, and droplet entrainment from liquid film is calculated by an entrainment correlation. For the verification of this method, Gill's experiment is analyzed, in which the transition from annular flow with no entrainment to equilibrium annular dispersed flow was observed. Analysis results can also show the similar transition tendency. The experimental results of radial distribution of droplet mass flux are compared with analysis results. The agreement is good for low liquid flow rate, but entrainment rate must be adjusted for high liquid flow rate, in which gas turbulence is thought to be modified by high droplet density. In future work the effect of high droplet density on turbulence should be considered. (author)

  19. Green power production by co-gasification of biomass in coal-fired oxygen-blown entrained-flow based IGCC processes

    Energy Technology Data Exchange (ETDEWEB)

    Van Ree, R; Korbee, R; De Smidt, R P; Jansen, D [ECN Fuels Conversion and Environment, Petten (Netherlands); Baumann, H R; Ullrich, N [Krupp Uhde, Dortmund (Germany); Haupt, G; Zimmerman, [Siemens, Erlangen (Germany)

    1998-11-01

    The use of coal for large scale power production meets a growing environmental concern. In spite of the fact that clean coal conversion technologies integrated with high-efficiency power production facilities, such as IGCC, are developed, the aim for sustainable development strives for a power production system based on renewable energy sources. One of the most promising renewable energy sources that can be used in the Netherlands is biomass, i.e. organic waste materials and/or energy crops. To accelerate the introduction of this material, in a technical and economically acceptable way, co-gasification with fossil fuels, in particular coal, in large scale IGCC processes is considered. In this paper the technical feasibility, economic profitability, and environmental acceptability of co-gasification of biomass in coal-fired oxygen-blown entrained-flow based IGM is discussed. Both a base-case coal-fired oxygen-blown entrained-flow based IGCC process - showing strong resemblance to the Puertollano IGCC plant in Spain - and three co-gasification concepts, viz.: (1) a concept with separate dry coal and biomass feeding systems, (2) a concept with a combined dry coal/biomass-derived pyrolysis char feeding system, and (3) a concept with parallel biomass pre-treatment/gasification and combined fuel gas clean-up/power production, were defined for further consideration. The base-case system and the co-gasification concepts as well are modelled in the flowsheet simulation package ASPEN{sup +}. Steady-state integral system calculations resulted in an overall net electrical plant efficiency for the base-case system of 50. 1 %LHV (48.3 %HHV). Replacing about 10 % of the total thermal plant input (coal) by biomass (willow) resulted in a decrease of the overall net electrical plant efficiency of 1.4 to 2.1 %-points LHV, avoided specific CO2 emissions of 40-49 g/kWh{sub e}, and total avoided CO2 emissions of about 129 to 159 kt/a, all depending on the co-gasification concept

  20. De-entrainment phenomena on vertical tubes in droplet cross flow. Informal report

    International Nuclear Information System (INIS)

    Dallman, J.C.; Kirchner, W.L.

    1980-04-01

    In this study, flow conditions in the upper plenum of a PWR during the reflood stage of a loss-of-coolant accident (LOCA) are simulated using water sprays and a draft-induced wind tunnel. The de-entrainment efficiencies of isolated structures are presented for a variety of air-water droplet cross flow conditions. Since droplet splashing and/or bouncing from the draining liquid film is not accounted for in classical inertial impaction theory, there is substantial disagreement between measurement and the theory. The de-entrainment efficiencies of isolated tubes are extrapolated to those of tubes in a multiple tube array, and a predictive relation is presented for the overall de-entrainment eficiency of multiple tube arrays

  1. Laboratory simulations of cumulus cloud flows explain the entrainment anomaly

    Science.gov (United States)

    Narasimha, Roddam; Diwan, Sourabh S.; Subrahmanyam, Duvvuri; Sreenivas, K. R.; Bhat, G. S.

    2010-11-01

    In the present laboratory experiments, cumulus cloud flows are simulated by starting plumes and jets subjected to off-source heat addition in amounts that are dynamically similar to latent heat release due to condensation in real clouds. The setup permits incorporation of features like atmospheric inversion layers and the active control of off-source heat addition. Herein we report, for the first time, simulation of five different cumulus cloud types (and many shapes), including three genera and three species (WMO Atlas 1987), which show striking resemblance to real clouds. It is known that the rate of entrainment in cumulus cloud flows is much less than that in classical plumes - the main reason for the failure of early entrainment models. Some of the previous studies on steady-state jets and plumes (done in a similar setup) have attributed this anomaly to the disruption of the large-scale turbulent structures upon the addition of off-source heat. We present estimates of entrainment coefficients from these measurements which show a qualitatively consistent variation with height. We propose that this explains the observed entrainment anomaly in cumulus clouds; further experiments are planned to address this question in the context of starting jets and plumes.

  2. Product Characterization for Entrained Flow Coal/Biomass Co-Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Maghzi, Shawn; Subramanian, Ramanathan; Rizeq, George; Singh, Surinder; McDermott, John; Eiteneer, Boris; Ladd, David; Vazquez, Arturo; Anderson, Denise; Bates, Noel

    2011-09-30

    The U.S. Department of Energy‘s National Energy Technology Laboratory (DOE NETL) is exploring affordable technologies and processes to convert domestic coal and biomass resources to high-quality liquid hydrocarbon fuels. This interest is primarily motivated by the need to increase energy security and reduce greenhouse gas emissions in the United States. Gasification technologies represent clean, flexible and efficient conversion pathways to utilize coal and biomass resources. Substantial experience and knowledge had been developed worldwide on gasification of either coal or biomass. However, reliable data on effects of blending various biomass fuels with coal during gasification process and resulting syngas composition are lacking. In this project, GE Global Research performed a complete characterization of the gas, liquid and solid products that result from the co-gasification of coal/biomass mixtures. This work was performed using a bench-scale gasifier (BSG) and a pilot-scale entrained flow gasifier (EFG). This project focused on comprehensive characterization of the products from gasifying coal/biomass mixtures in a high-temperature, high-pressure entrained flow gasifier. Results from this project provide guidance on appropriate gas clean-up systems and optimization of operating parameters needed to develop and commercialize gasification technologies. GE‘s bench-scale test facility provided the bulk of high-fidelity quantitative data under temperature, heating rate, and residence time conditions closely matching those of commercial oxygen-blown entrained flow gasifiers. Energy and Environmental Research Center (EERC) pilot-scale test facility provided focused high temperature and pressure tests at entrained flow gasifier conditions. Accurate matching of syngas time-temperature history during cooling ensured that complex species interactions including homogeneous and heterogeneous processes such as particle nucleation, coagulation, surface condensation, and

  3. Product Characterization for Entrained Flow Coal/Biomass Co-Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Maghzi, Shawn [General Electric Global Research, Niskayuna, NY (United States); Subramanian, Ramanathan [General Electric Global Research, Niskayuna, NY (United States); Rizeq, George [General Electric Global Research, Niskayuna, NY (United States); Singh, Surinder [General Electric Global Research, Niskayuna, NY (United States); McDermott, John [General Electric Global Research, Niskayuna, NY (United States); Eiteneer, Boris [General Electric Global Research, Niskayuna, NY (United States); Ladd, David [General Electric Global Research, Niskayuna, NY (United States); Vazquez, Arturo [General Electric Global Research, Niskayuna, NY (United States); Anderson, Denise [General Electric Global Research, Niskayuna, NY (United States); Bates, Noel [General Electric Global Research, Niskayuna, NY (United States)

    2011-12-11

    The U.S. Department of Energy's National Energy Technology Laboratory (DOE NETL) is exploring affordable technologies and processes to convert domestic coal and biomass resources to high-quality liquid hydrocarbon fuels. This interest is primarily motivated by the need to increase energy security and reduce greenhouse gas emissions in the United States. Gasification technologies represent clean, flexible and efficient conversion pathways to utilize coal and biomass resources. Substantial experience and knowledge had been developed worldwide on gasification of either coal or biomass. However, reliable data on effects of blending various biomass fuels with coal during gasification process and resulting syngas composition are lacking. In this project, GE Global Research performed a complete characterization of the gas, liquid and solid products that result from the co-gasification of coal/biomass mixtures. This work was performed using a bench-scale gasifier (BSG) and a pilot-scale entrained flow gasifier (EFG). This project focused on comprehensive characterization of the products from gasifying coal/biomass mixtures in a high-temperature, high-pressure entrained flow gasifier. Results from this project provide guidance on appropriate gas clean-up systems and optimization of operating parameters needed to develop and commercialize gasification technologies. GE's bench-scale test facility provided the bulk of high-fidelity quantitative data under temperature, heating rate, and residence time conditions closely matching those of commercial oxygen-blown entrained flow gasifiers. Energy and Environmental Research Center (EERC) pilot-scale test facility provided focused high temperature and pressure tests at entrained flow gasifier conditions. Accurate matching of syngas time-temperature history during cooling ensured that complex species interactions including homogeneous and heterogeneous processes such as particle nucleation, coagulation, surface condensation

  4. A review of recent developments on turbulent entrainment in stratified flows

    International Nuclear Information System (INIS)

    Cotel, Aline J

    2010-01-01

    Stratified interfaces are present in many geophysical flow situations, and transport across such an interface is an essential factor for correctly evaluating the physical processes taking place at many spatial and temporal scales in such flows. In order to accurately evaluate vertical and lateral transport occurring when a turbulent flow impinges on a stratified interface, the turbulent entrainment and vorticity generation mechanisms near the interface must be understood and quantified. Laboratory experiments were performed for three flow configurations: a vertical thermal, a sloping gravity current and a vertical turbulent jet with various tilt angles and precession speeds. All three flows impinged on an interface separating a two-layer stably stratified environment. The entrainment rate is quantified for each flow using laser-induced fluorescence and compared to predictions of Cotel and Breidenthal (1997 Appl. Sci. Res. 57 349-66). The possible applications of transport across stratified interfaces include the contribution of hydrothermal plumes to the global ocean energy budget, turbidity currents on the ocean floor, the design of lake de-stratification systems, modeling gas leaks from storage reservoirs, weather forecasting and global climate change.

  5. In-duct removal of mercury from coal-fired power plant flue gas by activated carbon: assessment of entrained flow versus wall surface contributions

    Energy Technology Data Exchange (ETDEWEB)

    Scala, F.; Chirone, R.; Lancia, A. [CNR, Naples (Italy). Institute for Research on Combustion

    2008-12-15

    In-duct mercury capture efficiency by activated carbon from coal-combustion flue gas was investigated. To this end, elemental mercury capture experiments were conducted at 100 C in a purposely designed 65-mm ID labscale pyrex apparatus operated as an entrained flow reactor. Gas residence times were varied between 0.7 and 2.0 s. Commercial-powdered activated carbon was continuously injected in the reactor and both mercury concentration and carbon elutriation rate were followed at the outlet. Transient mercury concentration profiles at the outlet showed that steady-state conditions were reached in a time interval of 15-20 min, much longer than the gas residence time in the reactor. Results indicate that the influence of the walls is non-negligible in determining the residence time of fine carbon particles in the adsorption zone, because of surface deposition and/or the establishment of a fluid-dynamic boundary layer near the walls. Total mercury capture efficiencies of 20-50% were obtained with carbon injection rates in the range 0.07-0.25 g/min. However, only a fraction of this capture was attributable to free-flowing carbon particles, a significant contribution coming from activated carbon staying near the reactor walls. Entrained bed experiments at lab-scale conditions are probably not properly representative of full-scale conditions, where the influence of wall interactions is lower. Moreover, previously reported entrained flow lab-scale mercury capture data should be reconsidered by taking into account the influence of particle-wall interactions.

  6. Characterization of Residual Particulates from Biomass Entrained Flow Gasification

    DEFF Research Database (Denmark)

    Qin, Ke; Lin, Weigang; Fæster, Søren

    2013-01-01

    Biomass gasification experiments were carried out in a bench scale entrained flow reactor, and the produced solid particles were collected by a cyclone and a metal filter for subsequent characterization. During wood gasification, the major part of the solid material collected in the filter is soot...

  7. Mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor.

    Science.gov (United States)

    Zhang, Yongsheng; Zhao, Lilin; Guo, Ruitao; Song, Na; Wang, Jiawei; Cao, Yan; Orndorff, William; Pan, Wei-ping

    2015-07-01

    In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were HgCl2, HgS and HgO. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor, existed in two forms, HgBr2 and HgO, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of HgBr2 and HgO in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time. Copyright © 2015. Published by Elsevier B.V.

  8. Influence of bed material entrainment and non-Newtonian rheology on turbulent geophysical flows dynamics. Numerical study

    Science.gov (United States)

    Eglit, M. E.; Yakubenko, A. E.; Yakubenko, T. A.

    2017-10-01

    This paper deals with the mathematical and numerical modeling of the propagation stage of geophysical gravity-driven flows, such as snow avalanches, mudflows, and rapid landslides. New mathematical models are presented which are based on full, not-depth-averaged equations of mechanics of continuous media. The models account for three important issues: non-Newtonian rheology of the moving material, entrainment of the bed material by the flow, and turbulence. The main objective is to investigate the effect of these three factors on the flow dynamics and on the value of the entrainment rate. To exclude the influence of many other factors, e.g., the complicated slope topography, only the motion down a long uniform slope with a constant inclination angle is studied numerically. Moreover, the entire flow from the front to the rear area was not modeled, but only its middle part where the flow is approximately uniform in length. One of the qualitative results is that in motion along homogeneous slope the mass entrainment increases the flow velocity and depth while the entrainment rate at large time tends to become constant which depends on the physical properties of the flow and the underlying material but not on the current values of the flow velocity and depth.

  9. Large eddy simulation of fire-induced buoyancy driven plume dispersion in an urban street canyon under perpendicular wind flow

    Energy Technology Data Exchange (ETDEWEB)

    Hu, L.H., E-mail: hlh@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026 (China); Huo, R.; Yang, D. [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2009-07-15

    The dispersion of fire-induced buoyancy driven plume in and above an idealized street canyon of 18 m (width) x 18 m (height) x 40 m (length) with a wind flow perpendicular to its axis was investigated by Fire Dynamics Simulator (FDS), Large Eddy Simulation (LES). Former studies, such as that by Oka [T.R. Oke, Street design and urban canopy layer climate, Energy Build. 11 (1988) 103-113], Gayev and Savory [Y.A. Gayev, E. Savory, Influence of street obstructions on flow processes within street canyons. J. Wind Eng. Ind. Aerodyn. 82 (1999) 89-103], Xie et al. [S. Xie, Y. Zhang, L. Qi, X. Tang, Spatial distribution of traffic-related pollutant concentrations in street canyons. Atmos. Environ. 37 (2003) 3213-3224], Baker et al. [J. Baker, H. L. Walker, X. M. Cai, A study of the dispersion and transport of reactive pollutants in and above street canyons-a large eddy simulation, Atmos. Environ. 38 (2004) 6883-6892] and Baik et al. [J.-J. Baik, Y.-S. Kang, J.-J. Kim, Modeling reactive pollutant dispersion in an urban street canyon, Atmos. Environ. 41 (2007) 934-949], focus on the flow pattern and pollutant dispersion in the street canyon with no buoyancy effect. Results showed that with the increase of the wind flow velocity, the dispersion pattern of a buoyant plume fell into four regimes. When the wind flow velocity increased up to a certain critical level, the buoyancy driven upward rising plume was re-entrained back into the street canyon. This is a dangerous situation as the harmful fire smoke will accumulate to pollute the environment and thus threaten the safety of the people in the street canyon. This critical re-entrainment wind velocity, as an important parameter to be concerned, was further revealed to increase asymptotically with the heat/buoyancy release rate of the fire.

  10. Large eddy simulation of fire-induced buoyancy driven plume dispersion in an urban street canyon under perpendicular wind flow.

    Science.gov (United States)

    Hu, L H; Huo, R; Yang, D

    2009-07-15

    The dispersion of fire-induced buoyancy driven plume in and above an idealized street canyon of 18 m (width) x 18 m (height) x 40 m (length) with a wind flow perpendicular to its axis was investigated by Fire Dynamics Simulator (FDS), Large Eddy Simulation (LES). Former studies, such as that by Oka [T.R. Oke, Street design and urban canopy layer climate, Energy Build. 11 (1988) 103-113], Gayev and Savory [Y.A. Gayev, E. Savory, Influence of street obstructions on flow processes within street canyons. J. Wind Eng. Ind. Aerodyn. 82 (1999) 89-103], Xie et al. [S. Xie, Y. Zhang, L. Qi, X. Tang, Spatial distribution of traffic-related pollutant concentrations in street canyons. Atmos. Environ. 37 (2003) 3213-3224], Baker et al. [J. Baker, H. L. Walker, X. M. Cai, A study of the dispersion and transport of reactive pollutants in and above street canyons--a large eddy simulation, Atmos. Environ. 38 (2004) 6883-6892] and Baik et al. [J.-J. Baik, Y.-S. Kang, J.-J. Kim, Modeling reactive pollutant dispersion in an urban street canyon, Atmos. Environ. 41 (2007) 934-949], focus on the flow pattern and pollutant dispersion in the street canyon with no buoyancy effect. Results showed that with the increase of the wind flow velocity, the dispersion pattern of a buoyant plume fell into four regimes. When the wind flow velocity increased up to a certain critical level, the buoyancy driven upward rising plume was re-entrained back into the street canyon. This is a dangerous situation as the harmful fire smoke will accumulate to pollute the environment and thus threaten the safety of the people in the street canyon. This critical re-entrainment wind velocity, as an important parameter to be concerned, was further revealed to increase asymptotically with the heat/buoyancy release rate of the fire.

  11. Large eddy simulation of fire-induced buoyancy driven plume dispersion in an urban street canyon under perpendicular wind flow

    International Nuclear Information System (INIS)

    Hu, L.H.; Huo, R.; Yang, D.

    2009-01-01

    The dispersion of fire-induced buoyancy driven plume in and above an idealized street canyon of 18 m (width) x 18 m (height) x 40 m (length) with a wind flow perpendicular to its axis was investigated by Fire Dynamics Simulator (FDS), Large Eddy Simulation (LES). Former studies, such as that by Oka [T.R. Oke, Street design and urban canopy layer climate, Energy Build. 11 (1988) 103-113], Gayev and Savory [Y.A. Gayev, E. Savory, Influence of street obstructions on flow processes within street canyons. J. Wind Eng. Ind. Aerodyn. 82 (1999) 89-103], Xie et al. [S. Xie, Y. Zhang, L. Qi, X. Tang, Spatial distribution of traffic-related pollutant concentrations in street canyons. Atmos. Environ. 37 (2003) 3213-3224], Baker et al. [J. Baker, H. L. Walker, X. M. Cai, A study of the dispersion and transport of reactive pollutants in and above street canyons-a large eddy simulation, Atmos. Environ. 38 (2004) 6883-6892] and Baik et al. [J.-J. Baik, Y.-S. Kang, J.-J. Kim, Modeling reactive pollutant dispersion in an urban street canyon, Atmos. Environ. 41 (2007) 934-949], focus on the flow pattern and pollutant dispersion in the street canyon with no buoyancy effect. Results showed that with the increase of the wind flow velocity, the dispersion pattern of a buoyant plume fell into four regimes. When the wind flow velocity increased up to a certain critical level, the buoyancy driven upward rising plume was re-entrained back into the street canyon. This is a dangerous situation as the harmful fire smoke will accumulate to pollute the environment and thus threaten the safety of the people in the street canyon. This critical re-entrainment wind velocity, as an important parameter to be concerned, was further revealed to increase asymptotically with the heat/buoyancy release rate of the fire.

  12. Electrification of particulate entrained fluid flows-Mechanisms, applications, and numerical methodology

    Science.gov (United States)

    Wei, Wei; Gu, Zhaolin

    2015-10-01

    Particulates in natural and industrial flows have two basic forms: liquid (droplet) and solid (particle). Droplets would be charged in the presence of the applied electric field (e.g. electrospray). Similar to the droplet charging, particles can also be charged under the external electric field (e.g. electrostatic precipitator), while in the absence of external electric field, tribo-electrostatic charging is almost unavoidable in gas-solid two-phase flows due to the consecutive particle contacts (e.g. electrostatic in fluidized bed or wind-blown sand). The particle charging may be beneficial, or detrimental. Although electrostatics in particulate entrained fluid flow systems have been so widely used and concerned, the mechanisms of particulate charging are still lack of a thorough understanding. The motivation of this review is to explore a clear understanding of particulate charging and movement of charged particulate in two-phase flows, by summarizing the electrification mechanisms, physical models of particulate charging, and methods of charging/charged particulate entrained fluid flow simulations. Two effective methods can make droplets charged in industrial applications: corona charging and induction charging. The droplet charge to mass ratio by corona charging is more than induction discharge. The particle charging through collisions could be attributed to electron transfer, ion transfer, material transfer, and/or aqueous ion shift on particle surfaces. The charges on charged particulate surface can be measured, nevertheless, the charging process in nature or industry is difficult to monitor. The simulation method might build a bridge of investigating from the charging process to finally charged state on particulate surface in particulate entrained fluid flows. The methodology combining the interface tracking under the action of the applied electric with the fluid flow governing equations is applicable to the study of electrohydrodynamics problems. The charge

  13. Ash transformation in suspension fired boilers co-firing coal and straw

    DEFF Research Database (Denmark)

    Zheng, Yuanjing; Jensen, Peter Arendt; Jensen, Anker Degn

    To study the influence of local conditions on the reaction between gaseous KCl and kaolin or coal fly ash experiments were done on CHECs electrically heated entrained flow reactor, which can simulate the local conditions in suspension fired boilers. The experimental results were compared with mod...

  14. Ash transformation during co-firing coal and straw

    DEFF Research Database (Denmark)

    Zheng, Yuanjing; Jensen, Peter Arendt; Jensen, Anker Degn

    2007-01-01

    Co-firing straw with coal in pulverized fuel boilers can cause problems related to fly ash utilization, deposit formation, corrosion and SCR catalyst deactivation due to the high contents of Cl and K in the ash. To investigate the interaction between coal and straw ash and the effect of coal...... quality on fly ash and deposit properties, straw was co-fired with three kinds of coal in an entrained flow reactor. The compositions of the produced ashes were compared to the available literature data to find suitable scaling parameters that can be used to predict the composition of ash from straw...... and coal co-firing. Reasonable agreement in fly ash compositions regarding total K and fraction of water soluble K was obtained between co-firing in an entrained flow reactor and full-scale plants. Capture of potassium and subsequent release of HCl can be achieved by sulphation with SO2 and more...

  15. Cladding motion and entrainment during loss of flow in the LMFBR

    International Nuclear Information System (INIS)

    Scale, T.J.; Eggen, D.T.

    1978-01-01

    The study that has been undertaken here is to characterize the loss of flow with appropriate dimensionless numbers such as Re, sup(p)vap/Psteel, sup(Dh/L), and to suggest a minimum Re, necessary for entrainment of simulant cladding material under transient melting. In particular, we are interested in the downward flow of vapor over an intact rod undergoing a loss of flow or loss of heat sink. (author)

  16. Free-surface entrainment into a rimming flow containing surfactants

    Science.gov (United States)

    Thoroddsen, S. T.; Tan, Y.-K.

    2004-02-01

    We study experimentally the free-surface entrainment of tubes into a steady rimming flow formed inside a partially filled horizontally rotating cylinder. The liquid consists of a glycerin-water mixture containing surfactants (fatty acids). The phenomenon does not occur without the surfactants and the details are sensitive to their concentration. The entrainment of numerous closely spaced air tubes and/or surfactant columns can start intermittently along a two-dimensional stagnation line, but is usually associated with the appearance of an axially periodic vortex structure, the so-called shark teeth, which fixes the spanwise location of these tubes. The number of tubes is governed by the three-dimensional shape of the free surface, reducing from more than 10 to only two in each trough, as the rotation rate is increased. The tubes vary in diameter from 10-30 μm and can extend hundreds of diameters into the liquid layer before breaking up into a continuous stream of bubbles and/or drops. The tubes are driven through the stagnation line by the strong viscous shear and are stretched in the downstream direction. The entrainment starts when the Capillary number Ca=μωR/σ≃0.4.

  17. Physical modelling of near-wall phenomena in entrained-flow coal gasifiers

    OpenAIRE

    Troiano, Maurizio

    2015-01-01

    Combustion and gasification under slagging conditions are key aspects of the design of modern entrained-flow reactors for thermal conversion of solid fuels, aimed at increasing the overall energy efficiency. In these systems, solid particles migrate toward the reactor walls, due to swirled/tangential flow induced in the reaction chamber and to turbophoresis, generating, thanks to the very high operating temperatures, a slag layer that flows along the reactor internal walls and is drained to t...

  18. Parameterization of a numerical 2-D debris flow model with entrainment: a case study of the Faucon catchment, Southern French Alps

    Directory of Open Access Journals (Sweden)

    H. Y. Hussin

    2012-10-01

    Full Text Available The occurrence of debris flows has been recorded for more than a century in the European Alps, accounting for the risk to settlements and other human infrastructure that have led to death, building damage and traffic disruptions. One of the difficulties in the quantitative hazard assessment of debris flows is estimating the run-out behavior, which includes the run-out distance and the related hazard intensities like the height and velocity of a debris flow. In addition, as observed in the French Alps, the process of entrainment of material during the run-out can be 10–50 times in volume with respect to the initially mobilized mass triggered at the source area. The entrainment process is evidently an important factor that can further determine the magnitude and intensity of debris flows. Research on numerical modeling of debris flow entrainment is still ongoing and involves some difficulties. This is partly due to our lack of knowledge of the actual process of the uptake and incorporation of material and due the effect of entrainment on the final behavior of a debris flow. Therefore, it is important to model the effects of this key erosional process on the formation of run-outs and related intensities. In this study we analyzed a debris flow with high entrainment rates that occurred in 2003 at the Faucon catchment in the Barcelonnette Basin (Southern French Alps. The historic event was back-analyzed using the Voellmy rheology and an entrainment model imbedded in the RAMMS 2-D numerical modeling software. A sensitivity analysis of the rheological and entrainment parameters was carried out and the effects of modeling with entrainment on the debris flow run-out, height and velocity were assessed.

  19. Particle re-entrainment from a powder deposit in an horizontal air flow

    International Nuclear Information System (INIS)

    Alloul, L.; Witschger, O.; Alloul, L.; Renoux, A.; Le Dur, D.; Monnatte, J.

    2000-01-01

    Particle re-entrainment from surfaces to turbulent air flow is an important subject in many different fields like nuclear safety, environmental air pollution, sediment transport by wind, surface contamination in semiconductor operations. Theoretical and experimental studies have been numerous and cover different aspects of the phenomena. Although a number of theoretical works have been devoted for describing the mechanisms of detachment of primary spherical particles form flat smooth surfaces in a turbulent flow, experimental data are still needed in order to comparison. Moreover, the knowledge of the effect of parameters related to the deposit (monolayer, multilayer, cone-like pile), the powder particles (particle-size distribution, adhesive properties), the surface (roughness,...),the airflow (velocity, acceleration, turbulence) or the environment (humidity,...) is still in an elementary stage. The main objective of our work is to contribute to the understanding and quantification of the parameters that govern the particle re-entrainment from a powder deposit in an turbulent horizontal airflow. Therefore, a new experimental facility called BISE (french acronym for wind tunnel for studying particle re-entrainment by airflow) has been designed and built in our laboratory. (authors)

  20. [Research progress in post-fire debris flow].

    Science.gov (United States)

    Di, Xue-ying; Tao, Yu-zhu

    2013-08-01

    The occurrence of the secondary disasters of forest fire has significant impacts on the environment quality and human health and safety. Post-fire debris flow is one of the most hazardous secondary disasters of forest fire. To understand the occurrence conditions of post-fire debris flow and to master its occurrence situation are the critical elements in post-fire hazard assessment. From the viewpoints of vegetation, precipitation threshold and debris flow material sources, this paper elaborated the impacts of forest fire on the debris flow, analyzed the geologic and geomorphic conditions, precipitation and slope condition that caused the post-fire debris flow as well as the primary mechanisms of debris-flow initiation caused by shallow landslide or surface runoff, and reviewed the research progress in the prediction and forecast of post-fire debris flow and the related control measures. In the future research, four aspects to be focused on were proposed, i. e., the quantification of the relationships between the fire behaviors and environmental factors and the post-fire debris flow, the quantitative research on the post-fire debris flow initiation and movement processes, the mechanistic model of post-fire debris flow, and the rapid and efficient control countermeasures of post-fire debris flow.

  1. Onset of entrainment and degree of dispersion in dual continuous horizontal oil-water flows

    Energy Technology Data Exchange (ETDEWEB)

    Al-Wahaibi, Talal [Department of Petroleum and Chemical Engineering, Sultan Qaboos University, P.O. Box 33, Al-Khoud, P.C. 123 (Oman); Angeli, Panagiota [Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2009-04-15

    The transition from stratified to dual continuous oil-water flow (where each phase retains its continuity but there is dispersion of one phase into the other) as well as the dispersed phase fractions in the layers of the dual continuous pattern, were studied experimentally. Transition to this pattern from stratified flow occurs when drops of one phase appear into the other (onset of entrainment). The studies were carried out in a 38 mm ID horizontal stainless steel test section using two different inlet geometries, a T- and a Y-junction. The patterns were visualized through a transparent acrylic section located at 7 m from the inlet using a high speed video camera. Phase distribution measurements in a pipe cross section were obtained just before the acrylic section with a local impedance probe and the results were used to calculate the volume fraction of each phase entrained into the other. The onset of entrainment was found to occur at lower superficial water velocities as the oil superficial velocities increased. However, the inlet geometry did not affect significantly the transition line. During dual continuous flow, the dispersion of one phase into the opposite was found to extend further away from the interface with increasing water superficial velocity for a certain oil superficial velocity. An increase in the superficial water velocity increased the entrained fraction of water in oil (E{sub w/o}) but there was no trend with the oil velocity. Similarly, an increase in the superficial oil velocity increased the fraction of oil drops in water (E{sub o/w}) but the water velocity had no clear effect. The entrainment fractions were affected by the inlet geometry, with the T-inlet resulting in higher entrainment than the Y-inlet, perhaps because of the increased mixing induced by the T-inlet. The difference between the two inlets increased as the oil and water velocities increased. (author)

  2. Laboratory Studies of Anomalous Entrainment in Cumulus Cloud Flows

    Science.gov (United States)

    Diwan, Sourabh S.; Narasimha, Roddam; Bhat, G. S.; Sreenivas, K. R.

    2011-12-01

    Entrainment in cumulus clouds has been a subject of investigation for the last sixty years, and continues to be a central issue in current research. The development of a laboratory facility that can simulate cumulus cloud evolution enables us to shed light on the problem. The apparatus for the purpose is based on a physical model of cloud flow as a plume with off-source diabatic heating that is dynamically similar to the effect of latent-heat release in natural clouds. We present a critical review of the experimental data so far obtained in such facilities on the variation of the entrainment coefficient in steady diabatic jets and plumes. Although there are some unexplained differences among different data sets, the dominant trend of the results compares favourably with recent numerical simulations on steady-state deep convection, and helps explain certain puzzles in the fluid dynamics of clouds.

  3. Laboratory Studies of Anomalous Entrainment in Cumulus Cloud Flows

    International Nuclear Information System (INIS)

    Diwan, Sourabh S; Narasimha, Roddam; Sreenivas, K R; Bhat, G S

    2011-01-01

    Entrainment in cumulus clouds has been a subject of investigation for the last sixty years, and continues to be a central issue in current research. The development of a laboratory facility that can simulate cumulus cloud evolution enables us to shed light on the problem. The apparatus for the purpose is based on a physical model of cloud flow as a plume with off-source diabatic heating that is dynamically similar to the effect of latent-heat release in natural clouds. We present a critical review of the experimental data so far obtained in such facilities on the variation of the entrainment coefficient in steady diabatic jets and plumes. Although there are some unexplained differences among different data sets, the dominant trend of the results compares favourably with recent numerical simulations on steady-state deep convection, and helps explain certain puzzles in the fluid dynamics of clouds.

  4. Post-dryout heat transfer and entrained droplet sizes at low pressure and low flow conditions

    International Nuclear Information System (INIS)

    Jeong, H.Y.; No, H.C.

    1997-01-01

    The entrainment mechanisms and the entrained droplet sizes with relation to the flow regimes are investigated. Through the analysis of many experimental post-dryout data, it is shown that the most probable flow regime near dryout or quench front is not annular flow but churn-turbulent flow when the mass flux is low. A correlation describing the initial droplet size just after the CHF position at low mass flux is suggested through regression analysis. The history-dependent post-dryout model of Varone and Rohsenow replaced by the Webb-Chen model for wall-vapor heat transfer is used as a reference model in the analysis. In the post-dryout region at low pressure and low flow, it is found that the suggested one-dimensional mechanistic model is not applicable when the vapor superficial velocity is very low. This is explained by the change of main entrainment mechanism with the change of flow regime. In bubbly or slug flow a number of tiny droplets generated from bubble burst become important in the heat transfer after dryout. Therefore, the suggested correlation is valid only in the churn-turbulent flow regime (j g * = 0.5∼4.5). It is also suggested that the droplet size generated from the churn-turbulent surface is dependent not only on the pressure but also on the vapor velocity. It turns out that the present model can predict the measured cladding and vapor temperatures within 20% and 25%, respectively

  5. Experimental study of gas entrainment from surface swirl

    Energy Technology Data Exchange (ETDEWEB)

    Moudjed, B., E-mail: brahim.moudjed@cea.fr; Excoffon, J.; Riva, R.; Rossi, L., E-mail: lionel.rossi@cea.fr

    2016-12-15

    Gas entrainment from surface swirls is characterized using water experiments. A free surface shear flow is generated in an open channel flow. A suction nozzle is set at the bottom of the test section to induce a downward flow and provoke gas entrainment. An important originality of these experiments is the possibility to change the inlet condition so as to generate different turbulent shear flows. This is done by adding obstacles of different sizes and shapes at the end of a flat plate separating the inlet flow from a “stagnant” water area. Velocity fields and profiles, measured with the PIV technique, are provided both to describe the inlet conditions corresponding to various geometries and flow rates, and to characterize the temporal average shear flow generated within the centre part of the channel. Gas entrainment mappings are established from direct observations of the different flow configurations. These new results show that the threshold for the suction velocities required to entrain gas are similar for the configurations with small obstacles and the flat plate configuration triggering a standard shear flow. Increasing the size of the obstacles promotes gas entrainment and reduces the threshold values of the suction velocity to trigger gas entrainment. Shadowgraphy with image processing is used to present new results characterizing the geometrical properties of surface swirls and the quantity of gas entrained. Inlet configurations with obstacles generate larger surface swirls which move upstream from the suction nozzle centre whereas they are situated downstream with the flat plate configuration. Moreover, dimensionless power laws are found to be good approximations for the surface swirl width and the quantity of gas entrained. In addition to provide new insights about gas entrainment in analytical configurations relevant to Sodium cooled fast nuclear reactor, these results should provide different test cases for the validation of MCFD codes.

  6. Advanced One-Dimensional Entrained-Flow Gasifier Model Considering Melting Phenomenon of Ash

    Directory of Open Access Journals (Sweden)

    Jinsu Kim

    2018-04-01

    Full Text Available A one-dimensional model is developed to represent the ash-melting phenomenon, which was not considered in the previous one-dimensional (1-D entrained-flow gasifier model. We include sensible heat of slag and the fusion heat of ash in the heat balance equation. To consider the melting of ash, we propose an algorithm that calculates the energy balance for three scenarios based on temperature. We also use the composition and the thermal properties of anorthite mineral to express ash. gPROMS for differential equations is used to solve this algorithm in a simulation; the results include coal conversion, gas composition, and temperature profile. Based on the Texaco pilot plant gasifier, we validate our model. Our results show good agreement with previous experimental data. We conclude that the sensible heat of slag and the fusion heat of ash must be included in the entrained flow gasifier model.

  7. Entrainment effects in periodic forcing of the flow over a backward-facing step

    Science.gov (United States)

    Berk, T.; Medjnoun, T.; Ganapathisubramani, B.

    2017-07-01

    The effect of the Strouhal number on periodic forcing of the flow over a backward-facing step (height, H ) is investigated experimentally. Forcing is applied by a synthetic jet at the edge of the step at Strouhal numbers ranging from 0.21 flow. In the present study, variations with Strouhal number are explained based on a continuous variation of entrainment of momentum into the recirculation region rather than on specific frequencies. The reattachment length is shown to decrease linearly with entrainment of momentum. Vertical momentum flux is driven by vortices generated by the forcing, and locally vertical momentum flux is shown to be qualitatively similar to circulation for all cases considered. Total circulation (and therewith entrainment of momentum and the effect on the reattachment length) is shown to decrease with Strouhal number, whereas this is not predicted by models based on specific low and high frequencies. An empirical model for the (decay of) circulation is derived by tracking vortices in phase-locked data. This model is used to decipher relevant scaling parameters that explain the variations in circulation, entrainment of momentum, and reattachment length. Three regimes of Strouhal number are identified. A low-Strouhal-number regime is observed for which vortices are formed at a late stage relative to the recirculation region, causing a decrease in effectiveness. For high Strouhal numbers, vortices are being reingested into the actuator or are packed so close together that they cancel each other, both decreasing the effectiveness of forcing. In the intermediate regime a vortex train is formed of which the decay of circulation increases for increasing Strouhal number. The scaling of this

  8. Large eddy simulation study of the kinetic energy entrainment by energetic turbulent flow structures in large wind farms

    Science.gov (United States)

    VerHulst, Claire; Meneveau, Charles

    2014-02-01

    In this study, we address the question of how kinetic energy is entrained into large wind turbine arrays and, in particular, how large-scale flow structures contribute to such entrainment. Previous research has shown this entrainment to be an important limiting factor in the performance of very large arrays where the flow becomes fully developed and there is a balance between the forcing of the atmospheric boundary layer and the resistance of the wind turbines. Given the high Reynolds numbers and domain sizes on the order of kilometers, we rely on wall-modeled large eddy simulation (LES) to simulate turbulent flow within the wind farm. Three-dimensional proper orthogonal decomposition (POD) analysis is then used to identify the most energetic flow structures present in the LES data. We quantify the contribution of each POD mode to the kinetic energy entrainment and its dependence on the layout of the wind turbine array. The primary large-scale structures are found to be streamwise, counter-rotating vortices located above the height of the wind turbines. While the flow is periodic, the geometry is not invariant to all horizontal translations due to the presence of the wind turbines and thus POD modes need not be Fourier modes. Differences of the obtained modes with Fourier modes are documented. Some of the modes are responsible for a large fraction of the kinetic energy flux to the wind turbine region. Surprisingly, more flow structures (POD modes) are needed to capture at least 40% of the turbulent kinetic energy, for which the POD analysis is optimal, than are needed to capture at least 40% of the kinetic energy flux to the turbines. For comparison, we consider the cases of aligned and staggered wind turbine arrays in a neutral atmospheric boundary layer as well as a reference case without wind turbines. While the general characteristics of the flow structures are robust, the net kinetic energy entrainment to the turbines depends on the presence and relative

  9. Mechanistic Model for Ash Deposit Formation in Biomass Suspension Firing. Part 1: Model Verification by Use of Entrained Flow Reactor Experiments

    DEFF Research Database (Denmark)

    Hansen, Stine Broholm; Jensen, Peter Arendt; Jappe Frandsen, Flemming

    2017-01-01

    used to describe the deposit formation rates and deposit chemistry observed in a series of entrained flow reactor (EFR) experiments using straw and wood as fuels. It was found that model #1 was not able to describe the observed influence of temperature on the deposit buildup rates, predicting a much...... differ in the description of the sticking probability of impacted particles: model #1 employs a reference viscosity in the description of the sticking probability, while model #2 combines impaction of viscoelastic particles on a solid surface with particle capture by a viscous surface. Both models were...

  10. Multiphysics Simulations of Entrained Flow Gasification. Part I: Validating the Nonreacting Flow Solver and the Particle Turbulent Dispersion Model

    KAUST Repository

    Kumar, Mayank; Ghoniem, Ahmed F.

    2012-01-01

    In this two-part paper, we describe the construction, validation, and application of a multiscale model of entrained flow gasification. The accuracy of the model is demonstrated by (1) rigorously constructing and validating the key constituent

  11. Entrainment in Laboratory Simulations of Cumulus Cloud Flows

    Science.gov (United States)

    Narasimha, R.; Diwan, S.; Subrahmanyam, D.; Sreenivas, K. R.; Bhat, G. S.

    2010-12-01

    A variety of cumulus cloud flows, including congestus (both shallow bubble and tall tower types), mediocris and fractus have been generated in a water tank by simulating the release of latent heat in real clouds. The simulation is achieved through ohmic heating, injected volumetrically into the flow by applying suitable voltages between diametral cross-sections of starting jets and plumes of electrically conducting fluid (acidified water). Dynamical similarity between atmospheric and laboratory cloud flows is achieved by duplicating values of an appropriate non-dimensional heat release number. Velocity measurements, made by laser instrumentation, show that the Taylor entrainment coefficient generally increases just above the level of commencement of heat injection (corresponding to condensation level in the real cloud). Subsequently the coefficient reaches a maximum before declining to the very low values that characterize tall cumulus towers. The experiments also simulate the protected core of real clouds. Cumulus Congestus : Atmospheric cloud (left), simulated laboratory cloud (right). Panels below show respectively total heat injected and vertical profile of heating in the laboratory cloud.

  12. What is the functional relevance of prefrontal cortex entrainment to hippocampal theta rhythms?

    Directory of Open Access Journals (Sweden)

    James Michael Hyman

    2011-03-01

    Full Text Available There has been considerable interest in the importance of oscillations in the brain and in how these oscillations relate to the firing of single neurons. Recently a number of studies have shown that the spiking of individual neurons in the medial prefrontal cortex (mPFC become entrained to the hippocampal (HPC theta rhythm. We recently showed that theta-entrained mPFC cells lost theta-entrainment specifically on error trials even though the firing rates of these cells did not change (Hyman et al., 2010. This implied that the level of HPC theta-entrainment of mPFC units was more predictive of trial outcome than differences in firing rates and that there is more information encoded by the mPFC on working memory tasks than can be accounted for by a simple rate code. Nevertheless, the functional meaning of mPFC entrainment to HPC theta remains a mystery. It is also unclear as to whether there are any differences in the nature of the information encoded by theta-entrained and non-entrained mPFC cells. In this review we discuss mPFC entrainment to HPC theta within the context of previous results as well as provide a more detailed analysis of the Hyman et al. (2010 data set. This re-analysis revealed that theta-entrained mPFC cells selectively encoded a variety of task relevant behaviors and stimuli while never theta-entrained mPFC cells were most strongly attuned to errors or the lack of expected rewards. In fact, these error responsive neurons were responsible for the error representations exhibited by the entire ensemble of mPFC neurons. A theta reset was also detected in the post-error period. While it is becoming increasingly evident that mPFC neurons exhibit correlates to virtually all cues and behaviors, perhaps phase-locking directs attention to the task-relevant representations required to solve a spatially based working memory task while the loss of theta-entrainment at the start of error trials may represent a shift of attention away from

  13. Dust-Firing of Straw and Additives

    DEFF Research Database (Denmark)

    Wu, Hao; Glarborg, Peter; Frandsen, Flemming

    2011-01-01

    In the present work, the ash chemistry and deposition behavior during straw dust-firing were studied by performing experiments in an entrained flow reactor. The effect of using spent bleaching earth (SBE) as an additive in straw combustion was also investigated by comparing with kaolinite. During...... dust-firing of straw, the large (>∼2.5 μm) fly ash particles generated were primarily molten or partially molten spherical particles rich in K, Si, and Ca, supplemented by Si-rich flake-shaped particles. The smaller fly ash particles (...

  14. Large Eddy and Interface Simulation (LEIS) of liquid entrainment in turbulent stratified flow

    International Nuclear Information System (INIS)

    Gulati, S.; Buongiorno, J.; Lakehal, D.

    2011-01-01

    Dryout of the liquid film on the fuel rods in BWR fuel assemblies leads to an abrupt decrease in heat transfer coefficient and can result in fuel failure. The process of mechanical mass transfer from the continuous liquid field into the continuous vapor field along the liquid-vapor interface is called entrainment and is the dominant depletion mechanism for the liquid film in annular flow. Using interface tracking methods combined with a Large Eddy Simulation approach, implemented in the Computational Multi-Fluid Dynamics (CMFD) code TransAT®, we are studying entrainment phenomena in BWR fuel assemblies. In this paper we report on the CMFD simulation approaches and the current validation effort for the code. (author)

  15. Experimental study of near-field entrainment of moderately overpressured jets

    Science.gov (United States)

    Solovitz, S.A.; Mastin, L.G.; Saffaraval, F.

    2011-01-01

    Particle image velocimetry (PIV) experiments have been conducted to study the velocity flow fields in the developing flow region of high-speed jets. These velocity distributions were examined to determine the entrained mass flow over a range of geometric and flow conditions, including overpressured cases up to an overpressure ratio of 2.83. In the region near the jet exit, all measured flows exhibited the same entrainment up until the location of the first shock when overpressured. Beyond this location, the entrainment was reduced with increasing overpressure ratio, falling to approximately 60 of the magnitudes seen when subsonic. Since entrainment ratios based on lower speed, subsonic results are typically used in one-dimensional volcanological models of plume development, the current analytical methods will underestimate the likelihood of column collapse. In addition, the concept of the entrainment ratio normalization is examined in detail, as several key assumptions in this methodology do not apply when overpressured.

  16. Effect of tides, river flow, and gate operations on entrainment of juvenile salmon into the interior Sacramento–San Joaquin River Delta

    Science.gov (United States)

    Perry, Russell W.; Brandes, Patricia L.; Burau, Jon R.; Sandstrom, Philip T.; Skalski, John R.

    2015-01-01

    Juvenile Chinook Salmon Oncorhynchus tshawytscha emigrating from natal tributaries of the Sacramento River, California, must negotiate the Sacramento-San Joaquin River Delta (hereafter, the Delta), a complex network of natural and man-made channels linking the Sacramento River with San Francisco Bay. Fish that enter the interior and southern Delta—the region to the south of the Sacramento River where water pumping stations are located—survive at a lower rate than fish that use alternative migration routes. Consequently, total survival decreases as the fraction of the population entering the interior Delta increases, thus spurring management actions to reduce the proportion of fish that are entrained into the interior Delta. To better inform management actions, we modeled entrainment probability as a function of hydrodynamic variables. We fitted alternative entrainment models to telemetry data that identified when tagged fish in the Sacramento River entered two river channels leading to the interior Delta (Georgiana Slough and the gated Delta Cross Channel). We found that the probability of entrainment into the interior Delta through both channels depended strongly on the river flow and tidal stage at the time of fish arrival at the river junction. Fish that arrived during ebb tides had a low entrainment probability, whereas fish that arrived during flood tides (i.e., when the river's flow was reversed) had a high probability of entering the interior Delta. We coupled our entrainment model with a flow simulation model to evaluate the effect of nighttime closures of the Delta Cross Channel gates on the daily probability of fish entrainment into the interior Delta. Relative to 24-h gate closures, nighttime closures increased daily entrainment probability by 3 percentage points on average if fish arrived at the river junction uniformly throughout the day and by only 1.3 percentage points if 85% of fish arrived at night. We illustrate how our model can be used to

  17. Experimental research of liquid entrainment through ADS-4 in AP1000

    International Nuclear Information System (INIS)

    Meng, Zhaoming; Dong, Bo; Wang, Laishun; Fu, Xiaoliang; Tian, Wenxi; Yang, Yanhua; Su, Guanghui

    2014-01-01

    Highlights: • We performed experimental research of liquid entrainment through ADS-4 in AP1000. • Effect of various factors on entrainment at T-junction was conducted. • Visualization research was conducted to make entrainment mechanism clear. - Abstract: In this study, based on a T-junction that consists of Automatic Depressurization System Stage Four (ADS-4) and hot leg in an AP1000 plant, a small-scale experimental research on entrainment at a T-junction was performed. This study mainly focused on the effect of various factors on entrainment, such as the effect of branch size, branch shape and liquid crossflow. The flow pattern map was plotted from the experimental data, and the visualization research indicated that the entrainment phenomena through a large size branch were apparently different from that through a small branch. Three entrainment phenomena were observed in the studies, two entrainment mechanisms could be found in the stratified flow regime entrainment area, the existence of branch contributed to generating intermittent flow in the horizontal main pipe, and the backflow region was observable in the vicinity of a large size branch inlet. Also, experimental research showed that downstream of the branch of T-junction had an important effect on the onset entrainment, and liquid crossflow did not seem to affect the onset entrainment

  18. Analysis of transient flows in gasoline direct injection systems: effects on unsteady air entrainment by the spray; Analyse des ecoulements transitoires dans les systemes d'injection directe essence: effets sur l'entrainement d'air instationnaire du spray

    Energy Technology Data Exchange (ETDEWEB)

    Delay, G

    2005-03-15

    The aim of this study is to determine instantaneous liquid flow rate oscillations effect on non stationary air entrainment of an injector conical spray (Gasoline Direct Injection). The tools we use are either experimental or numerical ones. An instantaneous flow rate determination method is used. It is based on pulsated flows physics and only requires the velocity at the centerline of a pipe mounted just before the injector. So, it is possible to 'rebuild' the instantaneous velocity distributions and then to get the instantaneous liquid flow rate (Laser Doppler Anemometry measurements). A mechanical and hydraulics modeling software (AMESim) is necessary to get injector outlet flow rate. Simulations are validated by both 'rebuilding' method results and common rail pressure measurements. Fluorescent Particle Image Velocimetry (FPIV), suited to dense two -phase flows, is used to measure air flow around and inside the conical spray. Velocity measurements close to the spray frontier are used to compute instantaneous air entrainment. Considering droplets momentum exchange with air and thanks to droplets diameters and liquid velocities measurements at the nozzle exit, a transient air entrainment model is proposed according to FPIV measurements. (author)

  19. Experimental investigation on the droplet entrainment from interfacial waves in air-water horizontal stratified flow

    International Nuclear Information System (INIS)

    Bae, Byeong Geon; Yun, Byong Jo; Kim, Kyoung Du

    2014-01-01

    It was mainly due to the fact that droplet entrainment affects the Peak Cladding Temperature (PCT) of the nuclear fuel rod in the Postulated accident conditions of NPP. Recently, droplet entrainment in the horizontally arranged primary piping system for the NPP is of interest because it affects directly the steam binding phenomena in the steam generators. Pan and Hanratty correlation is the only applicable one for the droplet entrainment rate model for horizontal flow. Moreover, there are no efforts for the model development on the basis of the droplet entrainment principal and physics phenomena. More recently, Korea Atomic Energy Research Institute (KAERI) proposed a new mechanistic droplet generation model applicable in the horizontal pipe for the SPACE code. However, constitutive relations in this new model require three model coefficients which have not yet been decided. The purpose of present work is determining three model coefficients by visualization experiment. For these model coefficients, the major physical parameters regarding the interfacial disturbance wave should be measured in this experiments. There are the wave slope, liquid fraction, wave hypotenuse length, wave velocity, wave frequency, and wavelength in the major physical parameters. The experiment was conducted at an air water horizontal rectangular channel with the PIV system. In this study, the experimental conditions were stratified-way flow during the droplet generation. Three coefficients were determined based on several data related to the interfacial wave. Additionally, we manufactured the parallel wire conductance probe to measure the fluctuating water level over time, and compared the wave height measured by the parallel wire conductance probe and image processing from images taken by high speed camera. Experimental investigation was performed for droplet entrainment from phase interface wave in an air-water stratified flow. In the experiments, we measured major physical parameters

  20. Model of large pool fires

    Energy Technology Data Exchange (ETDEWEB)

    Fay, J.A. [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)]. E-mail: jfay@mit.edu

    2006-08-21

    A two zone entrainment model of pool fires is proposed to depict the fluid flow and flame properties of the fire. Consisting of combustion and plume zones, it provides a consistent scheme for developing non-dimensional scaling parameters for correlating and extrapolating pool fire visible flame length, flame tilt, surface emissive power, and fuel evaporation rate. The model is extended to include grey gas thermal radiation from soot particles in the flame zone, accounting for emission and absorption in both optically thin and thick regions. A model of convective heat transfer from the combustion zone to the liquid fuel pool, and from a water substrate to cryogenic fuel pools spreading on water, provides evaporation rates for both adiabatic and non-adiabatic fires. The model is tested against field measurements of large scale pool fires, principally of LNG, and is generally in agreement with experimental values of all variables.

  1. Model of large pool fires

    International Nuclear Information System (INIS)

    Fay, J.A.

    2006-01-01

    A two zone entrainment model of pool fires is proposed to depict the fluid flow and flame properties of the fire. Consisting of combustion and plume zones, it provides a consistent scheme for developing non-dimensional scaling parameters for correlating and extrapolating pool fire visible flame length, flame tilt, surface emissive power, and fuel evaporation rate. The model is extended to include grey gas thermal radiation from soot particles in the flame zone, accounting for emission and absorption in both optically thin and thick regions. A model of convective heat transfer from the combustion zone to the liquid fuel pool, and from a water substrate to cryogenic fuel pools spreading on water, provides evaporation rates for both adiabatic and non-adiabatic fires. The model is tested against field measurements of large scale pool fires, principally of LNG, and is generally in agreement with experimental values of all variables

  2. Biomass co-firing under oxy-fuel conditions

    DEFF Research Database (Denmark)

    Álvarez, L.; Yin, Chungen; Riaza, J.

    2014-01-01

    This paper presents an experimental and numerical study on co-firing olive waste (0, 10%, 20% on mass basis) with two coals in an entrained flow reactor under three oxy-fuel conditions (21%O2/79%CO2, 30%O2/70%CO2 and 35%O2/65%CO2) and air–fuel condition. Co-firing biomass with coal was found...... to have favourable synergy effects in all the cases: it significantly improves the burnout and remarkably lowers NOx emissions. The reduced peak temperatures during co-firing can also help to mitigate deposition formation in real furnaces. Co-firing CO2-neutral biomass with coals under oxy-fuel conditions...... the model can be used to aid in design and optimization of large-scale biomass co-firing under oxy-fuel conditions....

  3. Kinematics of flow and sediment particles at entrainment and deposition

    Science.gov (United States)

    Antico, Federica; Sanches, Pedro; Aleixo, Rui; Ferreira, Rui M. L.

    2015-04-01

    A cohesionless granular bed subjected to a turbulent open-channel flow is analysed. The key objective is to clarify the kinematics of entrainment and deposition of individual sediment particles. In particular, we quantify a) the turbulent flow field in the vicinity of particles at the instants of their entrainment and of their deposition; b) the initial particle velocity and the particle velocity immediately before returning to rest. The experimental work was performed at the Hydraulics Laboratory of IST-UL in a 12.5 m long, 0.405 m wide glass-walled flume recirculating water and sediment through independent circuits. The granular bed was a 4.0 m long and 2.5 cm deep reach filled with 5 mm diameter glass beads packed (with some vibration) to a void fraction of 0.356, typical of random packing. Upstream the mobile bed reach the bed was composed of glued particles to ensure the development of a boundary layer with the same roughness. Laboratory tests were run under conditions of weak beadload transport with Shields parameters in the range 0.007 to 0.03. Froude numbers ranged from 0.63 to 0.95 while boundary Reynolds numbers were in the range 130 to 300. It was observed that the bed featured patches of regular arrangements: face centered cubic (fcc) or hexagonal close packing (hcp) blocks alternate with and body centered cubic (bcc) blocks. The resulting bed surface exhibits cleavage lines between blocks and there are spatial variations of bed elevation. The option for artificial sediment allowed for a simplified description of particle positioning at the instant of entrainment. In particular support and pivoting angles are found analytically. Skin friction angles were determind experimentally. The only relevant variables are exposure (defined as the ratio of the actual frontal projection of the exposed area to the area of a circle with 5 mm diameter) and protrusion (defined as the vertical distance between the apex of the particle and the mean local bed elevation

  4. Experimental studies on spray and gas entrainment characteristics of biodiesel fuel: Implications of gas entrained and fuel oxygen content on soot formation

    International Nuclear Information System (INIS)

    Kuti, Olawole Abiola; Nishida, Keiya; Zhu, Jingyu

    2013-01-01

    Experiments were performed inside the constant volume vessel to simulate the real diesel engine conditions. The LIF–PIV (Laser Induced Florescence – Particulate Image Velocimetry) technique was used to characterize the spray and gas entrainment characteristics of the fuels while the OH-chemiluminescence and two color pyrometry were applied to obtain information about the combustion processes. Biodiesel from palm oil (BDF (Biodiesel Fuel)) and the JIS #2 diesel fuel were utilized. It was observed that the SMD (Sauter mean diameter) obtained through an empirical equation decreased by increasing the injection pressure from 100 to 300 MPa and reducing the nozzle diameter from 0.16 to 0.08 mm. BDF has higher SMD values compared to diesel thus signifying inferior atomization. By increasing the injection pressure up to 300 MPa and reducing the nozzle diameter to 0.08 mm, the normal velocity and total mass flow rate of the entrained gas by the fuels increased. Due to higher viscosity and density properties, BDF possessed inferior atomization characteristics which made the normal velocity and total mass flow rate of the entrained gas lower compared to diesel. Due to inferior atomization which led to less gas being entrained upstream of the lift-off flame, the fuel oxygen content in BDF played a significant role in soot formation processes. - Highlights: • Spray and gas entrainment characteristics of biodiesel (BDF (Biodiesel Fuel)) and fuel were investigated. • Effect of injector parameters on BDF spray and gas entrainment characteristics was identified. • Higher viscosity and density of BDF yielded inferior spray atomization processes. • Gas entrainment velocity and mass flow rate of gas entrained by BDF lower. • Gas entrained had less effect on BDF's soot formation

  5. Effect of splash on the deposition and re-entrainment in annular mist flow

    International Nuclear Information System (INIS)

    Xie, Heng; Koshizuka, Seiichi; Oka, Yoshiaki

    2004-01-01

    The three-dimensional Moving Particle Semi-implicit (MPS) method is employed to simulate the deposition process of single droplet on the liquid film. The model accounts for the presence of inertial, gravitation, viscous and surface tension and is validated by comparison with experiment results. A one-dimensional mixture model is developed to calculate the necessary parameters for the simulation of deposition on the Boiling Water Reactor (BWR) condition. The correlations and methods on void fraction, entertainment fraction and droplet velocity and size distribution are employed to get the parameters of droplet and liquid film. The simulation results are analyzed to study the effect of splash on the deposition and re-entrainment process in annular-mist flow on the condition of BWR. It is found that the splash plays an important role in the deposition and re-entrainment process in high quality conditions of BWR. (author)

  6. Analysis of transient flows in gasoline direct injection systems: effects on unsteady air entrainment by the spray; Analyse des ecoulements transitoires dans les systemes d'injection directe essence: effets sur l'entrainement d'air instationnaire du spray

    Energy Technology Data Exchange (ETDEWEB)

    Delay, G.

    2005-03-15

    The aim of this study is to determine instantaneous liquid flow rate oscillations effect on non stationary air entrainment of an injector conical spray (Gasoline Direct Injection). The tools we use are either experimental or numerical ones. An instantaneous flow rate determination method is used. It is based on pulsated flows physics and only requires the velocity at the centerline of a pipe mounted just before the injector. So, it is possible to 'rebuild' the instantaneous velocity distributions and then to get the instantaneous liquid flow rate (Laser Doppler Anemometry measurements). A mechanical and hydraulics modeling software (AMESim) is necessary to get injector outlet flow rate. Simulations are validated by both 'rebuilding' method results and common rail pressure measurements. Fluorescent Particle Image Velocimetry (FPIV), suited to dense two -phase flows, is used to measure air flow around and inside the conical spray. Velocity measurements close to the spray frontier are used to compute instantaneous air entrainment. Considering droplets momentum exchange with air and thanks to droplets diameters and liquid velocities measurements at the nozzle exit, a transient air entrainment model is proposed according to FPIV measurements. (author)

  7. Debris flow analysis with a one dimensional dynamic run-out model that incorporates entrained material

    Science.gov (United States)

    Luna, Byron Quan; Remaître, Alexandre; van Asch, Theo; Malet, Jean-Philippe; van Westen, Cees

    2010-05-01

    Estimating the magnitude and the intensity of rapid landslides like debris flows is fundamental to evaluate quantitatively the hazard in a specific location. Intensity varies through the travelled course of the flow and can be described by physical features such as deposited volume, velocities, height of the flow, impact forces and pressures. Dynamic run-out models are able to characterize the distribution of the material, its intensity and define the zone where the elements will experience an impact. These models can provide valuable inputs for vulnerability and risk calculations. However, most dynamic run-out models assume a constant volume during the motion of the flow, ignoring the important role of material entrained along its path. Consequently, they neglect that the increase of volume enhances the mobility of the flow and can significantly influence the size of the potential impact area. An appropriate erosion mechanism needs to be established in the analyses of debris flows that will improve the results of dynamic modeling and consequently the quantitative evaluation of risk. The objective is to present and test a simple 1D debris flow model with a material entrainment concept based on limit equilibrium considerations and the generation of excess pore water pressure through undrained loading of the in situ bed material. The debris flow propagation model is based on a one dimensional finite difference solution of a depth-averaged form of the Navier-Stokes equations of fluid motions. The flow is treated as a laminar one phase material, which behavior is controlled by a visco-plastic Coulomb-Bingham rheology. The model parameters are evaluated and the model performance is tested on a debris flow event that occurred in 2003 in the Faucon torrent (Southern French Alps).

  8. Numerical investigation of slag formation in an entrained-flow gasifier

    Science.gov (United States)

    Zageris, G.; Geza, V.; Jakovics, A.

    2018-05-01

    A CFD mathematical model for an entrained-flow gasifier is constructed – the model of an actual gasifier is rendered in 3D and appropriately meshed. Then, the turbulent gas flow in the gasifier is modeled with the realizable k-ε approach, taking devolatilization, combustion and coal gasification in account. Various such simulations are conducted, obtaining results for different air inlet positions and by tracking particles of varying sizes undergoing devolatilization and gasification. The model identifies potential problematic zones where most particles collide with the gasifier walls, indicating risk regions where ash deposits could most likely form. In conclusion, effects on the formation of an ash layer of air inlet positioning and particle size allowed in the main gasifier tank are discussed, and viable solutions such as radial inlet positioning for decreasing the amount of undesirable deposits are proposed. We also conclude that the particular chemical reactions that take place inside the gasifier play a significant role in determining how slagging occurs inside a gasifier.

  9. Phenomenological modelling of CHF in annular flow in annuli using new models of droplet deposition and entrainment

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haibin, E-mail: hb-zhang@xjtu.edu.cn [School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049 (China); Department of Chemical Engineering, Imperial College, London SW7 2BY (United Kingdom); Hewitt, G.F., E-mail: g.hewitt@imperial.ac.uk [Department of Chemical Engineering, Imperial College, London SW7 2BY (United Kingdom)

    2016-08-15

    Highlights: • A phenomenological model to predict the CHF for flows in annuli is described. • New correlations of droplet entrainment and deposition are used. • The present model has good predictive capability in predicting CHF in annuli. - Abstract: In this paper, we present a phenomenological model to predict the CHF (critical heat flux) for upward annular flow in heated vertical annuli. In present model, a new set of correlations of droplet deposition and entrainment in annuli was used which were verified by comparison with the data of Moeck (1970) for developing liquid films in adiabatic annuli. In the results presented here, these new correlations have been used to predict 2249 independent data on critical heat flux (CHF) obtained both regarding internal heating of the rod as well as simultaneous heating of the rod and the outer tube in six heated vertical annuli under various mass flow rate, pressure and inlet quality and where the conditions were such that (as is most common) the CHF condition occurred in the annular flow regime. The comparisons between the calculated and measured CHFs showed that the present model has good predictive capability in predicting CHF.

  10. The effect of acceleration on turbulent entrainment

    International Nuclear Information System (INIS)

    Breidenthal, Robert E

    2008-01-01

    A new class of self-similar turbulent flows is proposed, which exhibits dramatically reduced entrainment rates. Under strong acceleration, the rotation period of the large-scale vortices is forced to decrease linearly in time. In ordinary unforced turbulence, the rotation period always increases linearly with time, at least in the mean. However, by imposing an exponential acceleration on the flow, the vortex rotation period is forced to become the e-folding timescale of the acceleration. If the e-folding timescale itself decreases linearly in time, the forcing is 'super-exponential', characterized by an acceleration parameter α. Based on dimensional and heuristic arguments, a model suggests that the dissipation rate is an exponential function of α and the dimensions of the conserved quantity of the flow. Acceleration decreases the dissipation and entrainment rates in all canonical laboratory flows except for Rayleigh-Taylor. Experiments of exponential jets and super-exponential transverse jets are in accord with the model. As noted by Johari, acceleration is the only known means of affecting the entrainment rate of the far-field jet. Numerical simulations of Rayleigh-Taylor flow by Cook and Greenough are also consistent. In the limit of large acceleration, vortices do not move far before their rotation period changes substantially. In this sense, extreme acceleration corresponds to stationary vortices.

  11. Entrainment by turbulent plumes

    Science.gov (United States)

    Parker, David; Burridge, Henry; Partridge, Jamie; Linden, Paul

    2017-11-01

    Plumes are of relevance to nature and real consequence to industry. While the Morton, Taylor & Turner (1956) plume model is able to estimate the mean physical flux parameters, the process of entrainment is only parametrised in a time-averaged sense and a deeper understanding is key to understanding how they evolve. Various flow configurations, resulting in different entrainment values, are considered; we perform simultaneous PIV and plume-edge detection on saline plumes in water resulting from a point source, a line source and a line source where a vertical wall is placed immediately adjacent. Of particular interest is the effect the large scale eddies, forming at the edge of the plume and engulfing ambient fluid, have on the entrainment process. By using velocity statistics in a coordinate system based on the instantaneous scalar edge of the plume the significance of this large scale engulfment is quantified. It is found that significant mass is transported outside the plumes, in particular in regions where large scale structures are absent creating regions of relatively high-momentum ambient fluid. This suggests that the large scale processes, whereby ambient fluid is engulfed into the plume, contribute significantly to the entrainment.

  12. Development of a Cl-impregnated activated carbon for entrained-flow capture of elemental mercury.

    Science.gov (United States)

    Ghorishi, S Behrooz; Keeney, Robert M; Serre, Shannon D; Gullett, Brian K; Jozewicz, Wojciech S

    2002-10-15

    Efforts to discern the role of an activated carbon's surface functional groups on the adsorption of elemental mercury (Hg0) and mercuric chloride demonstrated that chlorine (Cl) impregnation of a virgin activated carbon using dilute solutions of hydrogen chloride leads to increases (by a factor of 2-3) in fixed-bed capture of these mercury species. A commercially available activated carbon (DARCO FGD, NORITAmericas Inc. [FGD])was Cl-impregnated (Cl-FGD) [5 lb (2.3 kg) per batch] and tested for entrained-flow, short-time-scale capture of Hg0. In an entrained flow reactor, the Cl-FGD was introduced in Hg0-laden flue gases (86 ppb of Hg0) of varied compositions with gas/solid contact times of about 3-4 s, resulting in significant Hg0 removal (80-90%), compared to virgin FGD (10-15%). These levels of Hg0 removal were observed across a wide range of very low carbon-to-mercury weight ratios (1000-5000). Variation of the natural gas combustion flue gas composition, by doping with nitrogen oxides and sulfur dioxide, and the flow reactor temperature (100-200 degrees C) had minimal effects on Hg0 removal bythe Cl-FGD in these carbon-to-mercury weight ratios. These results demonstrate significant enhancement of activated carbon reactivity with minimal treatment and are applicable to combustion facilities equipped with downstream particulate matter removal such as an electrostatic precipitator.

  13. Detection of gas entrainment into liquid metals

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, T., E-mail: t.vogt@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Fluid Dynamics, 01328 Dresden (Germany); Boden, S. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Fluid Dynamics, 01328 Dresden (Germany); Andruszkiewicz, A. [Faculty of Mechanical and Power Engineering, Wroclaw University of Technology (Poland); Eckert, K. [Technische Universität Dresden, Institute of Fluid Mechanics, 01062 Dresden (Germany); Eckert, S.; Gerbeth, G. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Fluid Dynamics, 01328 Dresden (Germany)

    2015-12-01

    Highlights: • We present liquid metal experiments dedicated to gas entrainment on the free surface. • Ultrasonic and X-ray attenuation techniques have been used to study the mechanisms of gas entrainment. • A comparison between bubbly flow in water and GaInSn showed substantial differences. • Our results emphasize the importance of liquid metal experiments which are able to provide a suitable data base for numerical code validation. - Abstract: Entrainment of cover gas into the liquid metal coolant is one of the principal safety issues in the design of innovative liquid metal-cooled fast reactors. We present generic experimental studies of this phenomenon in low-melting metals. Ultrasonic and X-ray diagnostic tools were considered for a visualization of gas entrainment at the free surface of the melt. Laboratory experiments were conducted using the eutectic alloy GaInSn, which is liquid at room temperature. Vortex-activated entrainment of air at the free surface of a rotating flow was revealed by ultrasonic techniques. X-ray radioscopy was used to visualize the behavior of argon bubbles inside a slit geometry. The measurements reveal distinct differences between water and GaInSn, especially with respect to the process of bubble formation and the coalescence and breakup of bubbles. Our results emphasize the importance of liquid metal experiments which are able to provide a suitable data base for numerical code validation.

  14. Particle Entrainment under Turbulent Flow Conditions

    Science.gov (United States)

    Diplas, Panayiotis

    2009-11-01

    Erosion, transportation and deposition of sediments and pollutants influence the hydrosphere, pedosphere, biosphere and atmosphere in profound ways. The global amount of sediment eroded annually over the continental surface of the earth via the action of water and wind is estimated to be around 80 billion metric tons, with 20 of them delivered by rivers to the oceans. This redistribution of material over the surface of the earth affects most of its physical, chemical and biological processes in ways that are exceedingly difficult to comprehend. The criterion currently in use for predicting particle entrainment, originally proposed by Shields in 1936, emphasizes the time-averaged boundary shear stress and therefore is incapable of accounting for the fluctuating forces encountered in turbulent flows. A new criterion that was developed recently in an effort to overcome the limitations of the previous approach will be presented. It is hypothesized that not only the magnitude, but also the duration of energetic near bed turbulent events is relevant in predicting grain removal from the bed surface. It is therefore proposed that the product of force and its duration, or impulse, is a more appropriate and universal criterion for identifying conditions suitable for particle dislodgement. Analytical formulation of the problem and experimental data are used to examine the validity of the new criterion.

  15. Experimental and computational study and development of the bituminous coal entrained-flow air-blown gasifier for IGCC

    International Nuclear Information System (INIS)

    Abaimov, N A; Osipov, P V; Ryzhkov, A F

    2016-01-01

    In the paper the development of the advanced bituminous coal entrained-flow air- blown gasifier for the high power integrated gasification combined cycle is considered. The computational fluid dynamics technique is used as the basic development tool. The experiment on the pressurized entrained-flow gasifier was performed by “NPO CKTI” JSC for the thermochemical processes submodel verification. The kinetic constants for Kuznetsk bituminous coal (flame coal), obtained by thermal gravimetric analysis method, are used in the model. The calculation results obtained by the CFD model are in satisfactory agreements with experimental data. On the basis of the verified model the advanced gasifier structure was suggested which permits to increase the hydrogen content in the synthesis gas and consequently to improve the gas turbine efficiency. In order to meet the specified requirements vapor is added on the second stage of MHI type gasifier and heat necessary for air gasification is compensated by supplemental heating of the blasting air. (paper)

  16. Study of parameters and entrainment of a jet in cross-flow arrangement with transition at two low Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas, Camilo [Karlsruhe Institute of Technology, Institute for Chemical Technology and Polymer Chemistry, Karlsruhe (Germany); Convenio Andres Bello, Instituto Internacional de Investigaciones Educativas para la Integracion, La Paz (Bolivia); Denev, Jordan A.; Bockhorn, Henning [Karlsruhe Institute of Technology, Engler-Bunte-Institute, Combustion Division, Karlsruhe (Germany); Suntz, Rainer [Karlsruhe Institute of Technology, Institute for Chemical Technology and Polymer Chemistry, Karlsruhe (Germany)

    2012-10-15

    Investigation of the mixing process is one of the main issues in chemical engineering and combustion and the configuration of a jet into a cross-flow (JCF) is often employed for this purpose. Experimental data are gained for the symmetry plane in a JCF-arrangement of an air flow using a combination of particle image velocimetry (PIV) with laser-induced fluorescence (LIF). The experimental data with thoroughly measured boundary conditions are complemented with direct numerical simulations, which are based on idealized boundary conditions. Two similar cases are studied with a fixed jet-to-cross-flow velocity ratio of 3.5 and variable cross-flow Reynolds numbers equal to 4,120 and 8,240; in both cases the jet issues from the pipe at laminar conditions. This leads to a laminar-to-turbulent transition, which depends on the Reynolds number and occurs quicker for the case with higher Reynolds number in both experiments and simulations as well. It was found that the Reynolds number only slightly affects the jet trajectory, which in the case with the higher Reynolds number is slightly deeper. It is attributed to the changed boundary layer shape of the cross-flow. Leeward streamlines bend toward the jet and are responsible for the strong entrainment of cross-flow fluid into the jet. Velocity components are compared for the two Reynolds numbers at the leeward side at positions where strongest entrainment is present and a pressure minimum near the jet trajectory is found. The numerical simulations showed that entrainment is higher for the case with the higher Reynolds number. The latter is attributed to the earlier transition in this case. Fluid entrainment of the jet in cross-flow is more than twice stronger than for a similar flow of a jet issuing into a co-flowing stream. This comparison is made along the trajectory of the two jets at a distance of 5.5 jet diameters downstream and is based on the results from the direct numerical simulations and recently published

  17. Measurement of air entrainment in plasma jets

    International Nuclear Information System (INIS)

    Fincke, J.R.; Rodriquez, R.; Pentecost, C.G.

    1990-01-01

    The concentration and temperature of air entrained into argon and helium plasma jets has been measured using coherent anti-Stokes Raman spectroscopy (CARS). The argon plasma flow field is characterized by a short region of well behaved laminar flow near the nozzle exit followed by an abrupt transition to turbulence. Once the transition of turbulence occurs, air is rapidly mixed into the jet core. The location of the transition region is determined by the rapid cooling of the jet and the resulting increase in Reynolds number. In contrast, the helium plasma flow field never exceeds a Reynolds number of 200 and remains laminar. The entrainment process in this case is controlled by molecular diffusion rather than turbulent mixing. 9 refs., 5 figs., 1 tab

  18. Entrainment of bed material by Earth-surface mass flows: review and reformulation of depth-integrated theory

    Science.gov (United States)

    Iverson, Richard M.; Chaojun Ouyang,

    2015-01-01

    Earth-surface mass flows such as debris flows, rock avalanches, and dam-break floods can grow greatly in size and destructive potential by entraining bed material they encounter. Increasing use of depth-integrated mass- and momentum-conservation equations to model these erosive flows motivates a review of the underlying theory. Our review indicates that many existing models apply depth-integrated conservation principles incorrectly, leading to spurious inferences about the role of mass and momentum exchanges at flow-bed boundaries. Model discrepancies can be rectified by analyzing conservation of mass and momentum in a two-layer system consisting of a moving upper layer and static lower layer. Our analysis shows that erosion or deposition rates at the interface between layers must in general satisfy three jump conditions. These conditions impose constraints on valid erosion formulas, and they help determine the correct forms of depth-integrated conservation equations. Two of the three jump conditions are closely analogous to Rankine-Hugoniot conditions that describe the behavior of shocks in compressible gasses, and the third jump condition describes shear traction discontinuities that necessarily exist across eroding boundaries. Grain-fluid mixtures commonly behave as compressible materials as they undergo entrainment, because changes in bulk density occur as the mixtures mobilize and merge with an overriding flow. If no bulk density change occurs, then only the shear-traction jump condition applies. Even for this special case, however, accurate formulation of depth-integrated momentum equations requires a clear distinction between boundary shear tractions that exist in the presence or absence of bed erosion.

  19. Fire Source Accessibility of Water Mist Fire Suppression Improvement through Flow Method Control

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Jun Ho; Kim, Hyeong Taek; Kim, Yun Jung; Park, Mun Hee [KHNP CRI, Daejeon (Korea, Republic of)

    2013-10-15

    Recently, nuclear power plants set CO{sub 2} fire suppression system. However it is hard to establish and to maintain and it also has difficulties performing function test. Therefore, it needs to develop a new fire suppression system to replace the existing CO{sub 2} fire suppression systems in nuclear power plant. In fact, already, there exist alternatives - gas fire suppression system or clean fire extinguishing agent, but it is hard to apply because it requires a highly complicated plan. However, water mist fire suppression system which has both water system and gas system uses small amount of water and droplet, so it is excellent at oxygen displacement and more suitable for nuclear power plant because it can avoid second damage caused by fire fighting water. This paper explains about enclosure effect of water mist fire suppression. And it suggests a study direction about water mist fire source approach improvement and enclosure effect improvement, using flow method control of ventilation system. Water mist fire suppression can be influenced by various variable. And flow and direction of ventilation system are important variable. Expectations of the plan for more fire source ventilation system is as in the following. It enhances enclosure effects of water mists, so it improves extinguish performance. Also the same effect as a inert gas injection causes can be achieved. Lastly, it is considered that combustible accessibility of water mists will increase because of descending air currents.

  20. A Study of the Flow Field Surrounding Interacting Line Fires

    Directory of Open Access Journals (Sweden)

    Trevor Maynard

    2016-01-01

    Full Text Available The interaction of converging fires often leads to significant changes in fire behavior, including increased flame length, angle, and intensity. In this paper, the fluid mechanics of two adjacent line fires are studied both theoretically and experimentally. A simple potential flow model is used to explain the tilting of interacting flames towards each other, which results from a momentum imbalance triggered by fire geometry. The model was validated by measuring the velocity field surrounding stationary alcohol pool fires. The flow field was seeded with high-contrast colored smoke, and the motion of smoke structures was analyzed using a cross-correlation optical flow technique. The measured velocities and flame angles are found to compare reasonably with the predicted values, and an analogy between merging fires and wind-blown flames is proposed.

  1. Maximizing biofuel production in a thermochemical biorefinery by adding electrolytic hydrogen and by integrating torrefaction with entrained flow gasification

    DEFF Research Database (Denmark)

    Clausen, Lasse Røngaard

    2015-01-01

    double the biofuel production per biomass input by converting almost all of the carbon in the biomass feed to carbon stored in the biofuel product. Water or steam electrolysis can supply the hydrogen to the biorefinery and also the oxygen for the gasifier. This paper presents the design and thermodynamic...... analysis of two biorefineries integrating water electrolysis for the production of methanol. In both plants, torrefied woody biomass is supplied to an entrained flow gasifier, but in one of the plants, the torrefaction process occurs on-site, as it is integrated with the entrained flow gasification process....... The analysis shows that the biorefinery with integrated torrefaction has a higher biomass to methanol energy ratio (136% vs. 101%) as well as higher total energy efficiency (62% vs. 56%). By comparing with two identical biorefineries without electrolysis, it is concluded that the biorefinery with integrated...

  2. Dynamic modeling of Shell entrained flow gasifier in an integrated gasification combined cycle process

    International Nuclear Information System (INIS)

    Lee, Hyeon-Hui; Lee, Jae-Chul; Joo, Yong-Jin; Oh, Min; Lee, Chang-Ha

    2014-01-01

    Highlights: • Detailed dynamic model for the Shell entrained flow gasifier was developed. • The model included sub-models of reactor, membrane wall, gas quench and slag flow. • The dynamics of each zone including membrane wall in the gasifier were analyzed. • Cold gas efficiency (81.82%), gas fraction and temperature agreed with Shell data. • The model could be used as part of the overall IGCC simulation. - Abstract: The Shell coal gasification system is a single-stage, up-flow, oxygen-blown gasifier which utilizes dry pulverized coal with an entrained flow mechanism. Moreover, it has a membrane wall structure and operates in the slagging mode. This work provides a detailed dynamic model of the 300 MW Shell gasifier developed for use as part of an overall IGCC (integrated gasification combined cycle) process simulation. The model consists of several sub-models, such as a volatilization zone, reaction zone, quench zone, slag zone, and membrane wall zone, including heat transfers between the wall layers and steam generation. The dynamic results were illustrated and the validation of the gasifier model was confirmed by comparing the results in the steady state with the reference data. The product gases (H 2 and CO) began to come out from the exit of the reaction zone within 0.5 s, and nucleate boiling heat transfer was dominant in the water zone of the membrane wall due to high heat fluxes. The steady state of the process was reached at nearly t = 500 s, and our simulation data for the steady state, such as the temperature and composition of the syngas, the cold gas efficiency (81.82%), and carbon conversion (near 1.0) were in good agreement with the reference data

  3. Turbulent entrainment across turbulent-nonturbulent interfaces in stably stratified mixing layers

    Science.gov (United States)

    Watanabe, T.; Riley, J. J.; Nagata, K.

    2017-10-01

    The entrainment process in stably stratified mixing layers is studied in relation to the turbulent-nonturbulent interface (TNTI) using direct numerical simulations. The statistics are calculated with the interface coordinate in an Eulerian frame as well as with the Lagrangian fluid particles entrained from the nonturbulent to the turbulent regions. The characteristics of entrainment change as the buoyancy Reynolds number Reb decreases and the flow begins to layer. The baroclinic torque delays the enstrophy growth of the entrained fluids at small Reb, while this effect is less efficient for large Reb. The entrained particle movement within the TNTI layer is dominated by the small dissipative scales, and the rapid decay of the kinetic energy dissipation rate due to buoyancy causes the entrained particle movement relative to the interface location to become slower. Although the Eulerian statistics confirm that there exists turbulent fluid with strong vorticity or with large buoyancy frequency near the TNTI, the entrained fluid particles circumvent these regions by passing through the TNTI in strain-dominant regions or in regions with small buoyancy frequency. The multiparticle statistics show that once the nonturbulent fluid volumes are entrained, they are deformed into flattened shapes in the vertical direction and diffuse in the horizontal direction. When Reb is large enough for small-scale turbulence to exist, the entrained fluid is able to penetrate into the turbulent core region. Once the flow begins to layer with decreasing Reb, however, the entrained fluid volume remains near the outer edge of the turbulent region and forms a stably stratified layer without vertical overturning.

  4. Ignition characteristics of coal blends in an entrained flow furnace

    Energy Technology Data Exchange (ETDEWEB)

    J. Faundez; B. Arias; F. Rubiera; A. Arenillas; X. Garcia; A.L. Gordon; J.J. Pis [Universidad de Concepcion, Concepcion (Chile)

    2007-09-15

    Ignition tests were carried out on blends of three coals of different rank - subbituminous, high volatile and low volatile bituminous - in two entrained flow reactors. The ignition temperatures were determined from the gas evolution profiles (CO, CO{sub 2}, NO, O{sub 2}), while the mechanism of ignition was elucidated from these profiles and corroborated by high-speed video recording. Under the experimental conditions of high carbon loading, clear interactive effects were observed for all the blends. Ignition of the lower rank coals (subbituminous, high volatile bituminous) enhanced the ignition of the higher rank coal (low volatile bituminous) in the blends. The ignition temperatures of the blends of the low rank coals (subbituminous-high volatile bituminous) were additive. However, for the rest of the blends the ignition temperatures were always closer to the lower rank coal in the blend. 21 refs., 8 figs.

  5. Measured gas and particle temperatures in VTT's entrained flow reactor

    DEFF Research Database (Denmark)

    Clausen, Sønnik; Sørensen, L.H.

    2006-01-01

    Particle and gas temperature measurements were carried out in experiments on VTTs entrained flow reactor with 5% and 10% oxygen using Fourier transform infrared emission spectroscopy (FTIR). Particle temperature measurements were performed on polish coal,bark, wood, straw particles, and bark...... and wood particles treated with additive. A two-color technique with subtraction of the background light was used to estimate particle temperatures during experiments. A transmission-emission technique was used tomeasure the gas temperature in the reactor tube. Gas temperature measurements were in good...... agreement with thermocouple readings. Gas lines and bands from CO, CO2 and H2O can be observed in the spectra. CO was only observed at the first measuring port (100ms) with the strongest CO-signal seen during experiments with straw particles. Variations in gas concentration (CO2 and H2O) and the signal from...

  6. Onset of liquid droplet entrainment on a direct vessel injection system for APR1400

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han-sol; Lee, Jae-Young [Handong Global University, Pohang (Korea, Republic of); Kim, Jong-Rok; Euh, Dong-Jin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    In this research, a series of visualization works was conducted to understand droplet entrainment of the flow pattern generated in direct vessel injection system(DVI) of Korea nuclear power plant, APR 1400. In the emergency situation of a nuclear power plant, reliability of DVI cooling can be an important issue. It is known that, the amount and the rate of entrainment during the DVI cooling process can significantly affect the total heat removal. To visualize the film Reynolds number closely related with onset of droplet entrainment induced by falling film flow and lateral air flow in a small gap, confocal chromatic sensing method for measuring accurately film thickness and depth averaging particle image velocimetry for film velocity were used. The results have been post processed 4G Insight software. By measuring two dimensional film Reynolds number, we can predict the onset of droplet entrainment and obtain visible breakup region intuitively. To visualize the droplet entrainment induced by falling film flow and lateral air flow in a small gap, shadowgraph method with CCD camera (2200fps, 1280 pixel X 800 pixel, ) on coated plate with super water-repellent agent was used. The results have been post processed using 4G Insight software. By measuring two dimensional film Reynolds number, we can predict the onset of droplet entrainment and obtain visible breakup region intuitively. By adopting both super hydrophobic coating method and shadowgraph method, entrainment in a narrow gap was successfully visualized that has rarely performed before and meaningful results for DVI system research fields have been made.

  7. Onset of liquid droplet entrainment on a direct vessel injection system for APR1400

    International Nuclear Information System (INIS)

    Kim, Han-sol; Lee, Jae-Young; Kim, Jong-Rok; Euh, Dong-Jin

    2016-01-01

    In this research, a series of visualization works was conducted to understand droplet entrainment of the flow pattern generated in direct vessel injection system(DVI) of Korea nuclear power plant, APR 1400. In the emergency situation of a nuclear power plant, reliability of DVI cooling can be an important issue. It is known that, the amount and the rate of entrainment during the DVI cooling process can significantly affect the total heat removal. To visualize the film Reynolds number closely related with onset of droplet entrainment induced by falling film flow and lateral air flow in a small gap, confocal chromatic sensing method for measuring accurately film thickness and depth averaging particle image velocimetry for film velocity were used. The results have been post processed 4G Insight software. By measuring two dimensional film Reynolds number, we can predict the onset of droplet entrainment and obtain visible breakup region intuitively. To visualize the droplet entrainment induced by falling film flow and lateral air flow in a small gap, shadowgraph method with CCD camera (2200fps, 1280 pixel X 800 pixel, ) on coated plate with super water-repellent agent was used. The results have been post processed using 4G Insight software. By measuring two dimensional film Reynolds number, we can predict the onset of droplet entrainment and obtain visible breakup region intuitively. By adopting both super hydrophobic coating method and shadowgraph method, entrainment in a narrow gap was successfully visualized that has rarely performed before and meaningful results for DVI system research fields have been made

  8. Study on CFD approach for gas entrainment phenomenon. Evaluation of applicability of finite element flow analysis

    International Nuclear Information System (INIS)

    Eguchi, Yuzuru

    2005-07-01

    The report is concerned with the evaluation of applicability of numerical modelling methods for the prediction of gas entrainment in an upper plenum of a sodium-cooled fast breeder reactor (FBR). Special attention was paid to applicability of variational multiscale (VMS) modelling in the context of the Finite Element Method. Two flow problems, which were experimentally shown to induce gas entrainment, are solved by a VMS code (MISTRAL). First, computing a benchmark problem of a gas entrainment swirl flow in a cylindrical vessel has led to the following results; (1) the VMS solution is able to resolve the precise vortex core structure more accurately than the non-VMS solution computed by Smart-fem. The circumferential velocity obtained from VMS computation rises almost double in comparison with the non-VMS solution, though it still underestimates the experimental values. (2) the half-value radius of the negative region of the second invariant of velocity gradient matches well between the VMS solution and non-VMS solution. (3) the negative/positive boundary of the second invariant of velocity gradient obtained from the VMS solution is closer to the vortex core radius observed in the experiment than that of the non-VMS solution, though the vortex dip length computed from the VMS result is shorter than the experimental value. Second, computing a benchmark problem of open channel flow with a square pillar and downstream suction pipe has led to the following results; (4) 2Δx-type spatial oscillation was observed due to lack of mesh subdivisions. (5) the distributional profile of the second invariant of velocity gradient is similar to that of the first problem (swirl flow in a cylindrical vessel), characterized by a strong negative region surrounded by a weak positive region. As a possible future plan, it may be necessary to analyze more precisely the features of unsteady vortices obtained in the second benchmark problem and to identify the difference (if any) from the

  9. An empirical correlation for the entrainment fraction at the onset of annular flow based on 2006 CHF look-up table

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Bo; Yang, Dongyu [Department of Mechanical Engineering, Rongcheng Campus, Harbin University of Science and Technology, Rongcheng 264300, Shandong (China); Gan, Zhihua, E-mail: gan_zhihua@zju.edu.cn [Institute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou (China); Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Hangzhou (China); National Quality Inspection Center of Refrigeration Equipment (Henan), Minquan (China)

    2017-06-15

    Highlights: • A parallel look-up table for the entrainment fraction at annular point was developed. • A correlation was given based on the selected database from 2006 CHF look-up table. • Its reliability on the other conditions in the look-up table was discussed. - Abstract: The critical heat flux (CHF) of gas-liquid flow plays an important role in the safety of industrial equipment. At present, the liquid film dryout model is widely used for predicting CHF in gas-liquid annular flow. Most parameters in this model can be determined by some empirical correlations which are valid under different conditions. However, up to now, the entrainment fraction at the onset of annular flow is always assumed due to the lack of relevant experimental data. In this paper, the normalized data of the 2006 CHF look-up table (LUT) which has been adopted widely, especially in the nuclear industry, were used. Firstly, the empirical correlations, provided for the onset of annular flow and the limiting quality, were employed. In the valid pressure and mass flux range of these correlations, the selected database from LUT was confirmed. Secondly, the liquid film model was built. The entrainment fraction at the onset of annular flow was obtained when the calculated CHF by the model agreed with the corresponding value in LUT. A parallel look-up table for it was developed. Its correlation including the Weber and the liquid Reynolds number at outlet was proposed. The errors are mostly within ±30%. Finally, its reliability on the other conditions in LUT, which are beyond the valid range of the empirical correlations used for determining the database, was discussed. All the conditions whose errors are outside ±30% of the predictions by the provided correlation were marked in the tables.

  10. Multiphysics Simulations of Entrained Flow Gasification. Part I: Validating the Nonreacting Flow Solver and the Particle Turbulent Dispersion Model

    KAUST Repository

    Kumar, Mayank

    2012-01-19

    In this two-part paper, we describe the construction, validation, and application of a multiscale model of entrained flow gasification. The accuracy of the model is demonstrated by (1) rigorously constructing and validating the key constituent submodels against relevant canonical test cases from the literature and (2) validating the integrated model against experimental data from laboratory scale and commercial scale gasifiers. In part I, the flow solver and particle turbulent dispersion models are validated against experimental data from nonswirling flow and swirling flow test cases in an axisymmetric sudden expansion geometry and a two-phase flow test case in a cylindrical bluff body geometry. Results show that while the large eddy simulation (LES) performs best among all tested models in predicting both swirling and nonswirling flows, the shear stress transport (SST) k-ω model is the best choice among the commonly used Reynolds-averaged Navier-Stokes (RANS) models. The particle turbulent dispersion model is accurate enough in predicting particle trajectories in complex turbulent flows when the underlying turbulent flow is well predicted. Moreover, a commonly used modeling constant in the particle dispersion model is optimized on the basis of comparisons with particle-phase experimental data for the two-phase flow bluff body case. © 2011 American Chemical Society.

  11. Three-field modeling with droplet entrainment and de-entrainment models for TRAC-M

    International Nuclear Information System (INIS)

    Lee, Sang Ik

    2005-02-01

    A three-field modeling has been developed and implemented to the basic one-dimensional components of TRAC-M/F90 (Modernized Transient Reactor Analysis Code, Fortran90) to improve the estimation of the behavior of droplet entrainment. the divide and conquer algorithmic technique is adjusted for the implementation after considering the verifications. The governing equations are composed of the conservation equations of each field with thermal-equilibrium assumption between the two liquid fields. As a result, three momentum equations, four mass equations including noncondensable gas mass equation and two energy equations are used. In the development of the momentum equation for an entrained droplet, two different kinds of approaches are tested: the simple force balance on a single droplet and the field-type equation based on the continuum assumption. The first showed unstable nature and the latter was chosen. All of the necessary empirical correlations were obtained from literatures, in particular, the physical models of COBRA-TF. The sensitivities of each empirical correlation were investigated where the effect of droplet diameter and droplet drag was found to be negligible. The advantages of the SETS numerical scheme in comparison with the semi-implicit nimerical scheme were addressed in the simulation time and the maximum allowed time-step size. Finally, the simulations of Collier and Hewitt's experiment were performed and it is concluded that the three-field model developed in the present study is reasonable. The predictions by the present code agree with the measured values within the RMS errors of 16.5% and 9.6% in the entrained liquid mass flow rates and the pressure gradients, respectively. Assessment on the physical models is performed. The wall and interfacial drag models were determined at first. After that, the assessments of entrainment model were performed. Wurtz's entrainment model, which was used in COBRA-TF and Kataoka and Ishii's model, were mainly

  12. Neurobiological foundations of neurologic music therapy: rhythmic entrainment and the motor system.

    Science.gov (United States)

    Thaut, Michael H; McIntosh, Gerald C; Hoemberg, Volker

    2014-01-01

    Entrainment is defined by a temporal locking process in which one system's motion or signal frequency entrains the frequency of another system. This process is a universal phenomenon that can be observed in physical (e.g., pendulum clocks) and biological systems (e.g., fire flies). However, entrainment can also be observed between human sensory and motor systems. The function of rhythmic entrainment in rehabilitative training and learning was established for the first time by Thaut and colleagues in several research studies in the early 1990s. It was shown that the inherent periodicity of auditory rhythmic patterns could entrain movement patterns in patients with movement disorders (see for a review: Thaut et al., 1999). Physiological, kinematic, and behavioral movement analysis showed very quickly that entrainment cues not only changed the timing of movement but also improved spatial and force parameters. Mathematical models have shown that anticipatory rhythmic templates as critical time constraints can result in the complete specification of the dynamics of a movement over the entire movement cycle, thereby optimizing motor planning and execution. Furthermore, temporal rhythmic entrainment has been successfully extended into applications in cognitive rehabilitation and speech and language rehabilitation, and thus become one of the major neurological mechanisms linking music and rhythm to brain rehabilitation. These findings provided a scientific basis for the development of neurologic music therapy.

  13. Neurobiological foundations of neurologic music therapy: rhythmic entrainment and the motor system

    Science.gov (United States)

    Thaut, Michael H.; McIntosh, Gerald C.; Hoemberg, Volker

    2015-01-01

    Entrainment is defined by a temporal locking process in which one system’s motion or signal frequency entrains the frequency of another system. This process is a universal phenomenon that can be observed in physical (e.g., pendulum clocks) and biological systems (e.g., fire flies). However, entrainment can also be observed between human sensory and motor systems. The function of rhythmic entrainment in rehabilitative training and learning was established for the first time by Thaut and colleagues in several research studies in the early 1990s. It was shown that the inherent periodicity of auditory rhythmic patterns could entrain movement patterns in patients with movement disorders (see for a review: Thaut et al., 1999). Physiological, kinematic, and behavioral movement analysis showed very quickly that entrainment cues not only changed the timing of movement but also improved spatial and force parameters. Mathematical models have shown that anticipatory rhythmic templates as critical time constraints can result in the complete specification of the dynamics of a movement over the entire movement cycle, thereby optimizing motor planning and execution. Furthermore, temporal rhythmic entrainment has been successfully extended into applications in cognitive rehabilitation and speech and language rehabilitation, and thus become one of the major neurological mechanisms linking music and rhythm to brain rehabilitation. These findings provided a scientific basis for the development of neurologic music therapy. PMID:25774137

  14. Neurobiological Foundations of Neurologic Music Therapy: Rhythmic Entrainment and the Motor System

    Directory of Open Access Journals (Sweden)

    Michael eThaut

    2015-02-01

    Full Text Available AbstractEntrainment is defined by a temporal locking process in which one system’s motion or signal frequency entrains the frequency of another system. This process is a universal phenomenon that can be observed in physical (e.g., pendulum clocks and biological systems (e.g. fire flies. However, entrainment can also be observed between human sensory and motor systems. The function of rhythmic entrainment in rehabilitative training and learning was established for the first time by Thaut and colleagues in several research studies in the early 1990s. It was shown that the inherent periodicity of auditory rhythmic patterns could entrain movement patterns in patients with movement disorders (see for a review: Thaut et al, 1999. Physiological, kinematic and behavioral movement analysis showed very quickly that entrainment cues not only changed the timing of movement but also improved spatial and force parameters. Mathematical models have shown that anticipatory rhythmic templates as critical time constraints can result in the complete specification of the dynamics of a movement over the entire movement cycle, thereby optimizing motor planning and execution. Furthermore, temporal rhythmic entrainment has been successfully extended into applications in cognitive rehabilitation and speech and language rehabilitation, and thus become one of the major neurological mechanisms linking music and rhythm to brain rehabilitation. These findings provided a scientific basis for the development of Neurologic Music Therapy.

  15. Viscous entrainment on hairy surfaces

    Science.gov (United States)

    Nasto, Alice; Brun, P.-T.; Hosoi, A. E.

    2018-02-01

    Nectar-drinking bats and honeybees have tongues covered with hairlike structures, enhancing their ability to take up viscous nectar by dipping. Using a combination of model experiments and theory, we explore the physical mechanisms that govern viscous entrainment in a hairy texture. Hairy surfaces are fabricated using laser cut molds and casting samples with polydimethylsiloxane (PDMS) elastomer. We model the liquid trapped within the texture using a Darcy-Brinkmann-like approach and derive the drainage flow solution. The amount of fluid that is entrained is dependent on the viscosity of the fluid, the density of the hairs, and the withdrawal speed. Both experiments and theory reveal an optimal hair density to maximize fluid uptake.

  16. Sediment particle entrainment in an obstructed annular

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, Bruno Venturini; Siqueira, Renato do Nascimento [Faculdade do Centro Leste (UCL), Serra, ES (Brazil). Lab. de Fenomenos de Transporte], e-mail: brunovl@ucl.br, e-mail: renatons@ucl.br

    2006-07-01

    Flow in an annular region with internal cylinder rotation is a classic problem in fluid mechanics and has been widely studied. Besides its importance as a fundamental problem, flow in annular regions has several practical applications. This project was motivated by an application of this kind of flow to the drilling of oil and gas wells. In this work, an erosion apparatus was constructed in order to study the effect of the internal cylinder rotation on particle entrainment in an obstructed annular space and bed package as well. The study also analyzed the influence of height of the particles bed on the process performance. The experiment was designed so that the internal cylinder rotation could be measured by an encoder. The fluid temperature was measured by a thermocouple and the experiments were carried out at the temperature of 25 deg C. The study revealed that the particle entrainment for the height of the bed that is close to the center of the cylinders is negligible and the internal cylinder rotation provokes the movement and packing of the bed. For lower height of the bed, with same dimension of the annular gap, the particle entrainment process was satisfactory and the bed compaction was smaller than in the previous case, leading to a more efficient cleaning process in the annular space. (author)

  17. Presence of strong harmonics during visual entrainment: a magnetoencephalography study.

    Science.gov (United States)

    Heinrichs-Graham, Elizabeth; Wilson, Tony W

    2012-09-01

    Visual neurons are known to synchronize their firing with stimuli that flicker at a constant rate (e.g. 12Hz). These so-called visual steady-state responses (VSSR) are a well-studied phenomenon, yet the underlying mechanisms are widely disagreed upon. Furthermore, there is limited evidence that visual neurons may simultaneously synchronize at harmonics of the stimulation frequency. We utilized magnetoencephalography (MEG) to examine synchronization at harmonics of the visual stimulation frequency (18Hz). MEG data were analyzed for event-related-synchronization (ERS) at the fundamental frequency, 36, 54, and 72Hz. We found strong ERS in all bands. Only 31% of participants showed maximum entrainment at the fundamental; others showed stronger entrainment at either 36 or 54Hz. The cortical foci of these responses indicated that the harmonics involved cortices that were partially distinct from the fundamental. These findings suggest that spatially-overlapping subpopulations of neurons are simultaneously entrained at different harmonics of the stimulus frequency. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. The influence of air flow speed on fire propagation in object

    Directory of Open Access Journals (Sweden)

    Jevtić Radoje

    2015-01-01

    Full Text Available Fire presents the process of the uncontrolled combustion that makes material damage and endangers human lives. It is important to know the factors that fire depends on for success projecting and realization of fire protection systems. One of such factors is different air flow that could be presented as wind, draft and the like. The simulation of different air flow speeds and its influences on fire propagation in object were analyzed in this paper.

  19. A numerical model for chemical reaction on slag layer surface and slag layer behavior in entrained-flow gasifier

    Directory of Open Access Journals (Sweden)

    Liu Sheng

    2013-01-01

    Full Text Available The paper concerns with slag layer accumulation, chemical reaction on slag layer surface, and slag layer flow, heat and mass transfer on the wall of entrained-flow coal gasifier. A slag layer model is developed to simulate slag layer behaviors in the coal gasifier. This 3-D model can predict temperature, slag particle disposition rate, disposition particle composition, and syngas distribution in the gasifier hearth. The model is used to evaluate the effects of O2/coal ratio on slag layer behaviors.

  20. Fluid Dynamics of Pressurized, Entrained Coal Gasifiers

    International Nuclear Information System (INIS)

    1997-01-01

    Pressurized, entrained gasification is a promising new technology for the clean and efficient combustion of coal. Its principle is to operate a coal gasifier at a high inlet gas velocity to increase the inflow of reactants, and at an elevated pressure to raise the overall efficiency of the process. Unfortunately, because of the extraordinary difficulties involved in performing measurements in hot, pressurized, high-velocity pilot plants, its fluid dynamics are largely unknown. Thus the designer cannot predict with certainty crucial phenomena like erosion, heat transfer and solid capture. In this context, we are conducting a study of the fluid dynamics of Pressurized Entrained Coal Gasifiers (PECGs). The idea is to simulate the flows in generic industrial PECGs using dimensional similitude. To this end, we employ a unique entrained gas-solid flow facility with the flexibility to recycle--rather than discard--gases other than air. By matching five dimensionless parameters, suspensions in mixtures of helium, carbon dioxide and sulfur hexafluoride simulate the effects of pressure and scale-upon the fluid dynamics of PECGs. Because it operates under cold, atmospheric conditions, the laboratory facility is ideal for detailed measurements

  1. Effect of Entrainment and Overflow Occurrences on Concentration Profile in PUREX Flow Sheet

    International Nuclear Information System (INIS)

    Ueda, Yoshinori; Ishii, Junichi; Matsumoto, Shiro

    2003-01-01

    A deviation in the operational condition of a mixer settler and a centrifugal contactor causes an entrainment or an overflow, which affects the concentration profile. Although there has been no quantitative study about the effect of such abnormal flows on the concentration profile, the occurrence of such abnormal flows has been severely restricted for a PUREX flow sheet. However, the restriction of abnormal flows can be relaxed when the effect of such flows is limited within the allowable range such that the concentration of the product does not deviate from its specification. This relaxation could serve to benefit a continuous operation under a certain degree of deviation from the operational condition and a smaller design load of a solvent extractor. From this viewpoint, the relationship between the magnitude of abnormal flows and the effect of them on the process was studied quantitatively using a specially developed code in a wide range of PUREX flow sheet conditions, and the possibility of this relaxation was investigated. The results showed that the effect of the abnormal flow on the concentration in the organic outflow or aqueous raffinate was dominated by the leakage fraction under normal conditions regardless of each specific flow sheet condition. The common correlations were found between the leakage fraction of uranium and plutonium under the occurrence of abnormal flows and that under no abnormal flow for the stripping and extracting conditions, respectively. Comparing the given correlations and the usual specification of the leakage fraction of uranium and plutonium suggested that the restriction of the abnormal flows could be relaxed for a usual PUREX flow sheet

  2. Leak detection on the DIII-D tokamak using helium entrainment techniques

    International Nuclear Information System (INIS)

    Brooks, N.H.; Baxi, C.; Anderson, P.

    1988-01-01

    The entrainment of helium in a viscous gas flow was utilized to compartmentalize, and then to pinpoint, a leak across the inner skin of the double-walled DIII-D vacuum vessel. Inaccessible from the outside, the leak connected the cooling channels in the wall interspace with the primary vacuum chamber. By entraining helium in the pressurized flow from the single-pass gas circulation system, well-defined portions of the wall were exposed to helium without disassembly of the poorly accessible cooling manifolds. Varying the helium injection point permitted the localization of the leak to a single 30 0 toroidal sector of the vessel. The exact location of the leak was found from inside the vessel by spraying helium on suspect regions, while sweeping the contents of the cooling channels to the foreline of a Varian Contraflow leak detector with a 0.1 Pa m 3 /s flow of nitrogen. Flow speed calculations were used to predict the response time to entrained helium of the actual leak detection setup

  3. Timing of susceptibility to post-fire debris flows in the western USA

    Science.gov (United States)

    DeGraff, Jerome V.; Cannon, Susan H.; Gartner, Joseph E.

    2015-01-01

    Watersheds recently burned by wildfires can have an increased susceptibility to debris flow, although little is known about how long this susceptibility persists, and how it changes over time. We here use a compilation of 75 debris-flow response and fire-ignition dates, vegetation and bedrock class, rainfall regime, and initiation process from throughout the western U.S. to address these issues. The great majority (85 percent) of debris flows occurred within the first 12 months following wildfire, with 71 percent within the first six months. Seven percent of the debris flows occurred between 1 and 1.5 years after a fire, or during the second rainy season to impact an area. Within the first 1.5 years following fires, all but one of the debris flows initiated through runoff-dominated processes, and debris flows occurred in similar proportions in forested and non-forested landscapes. Geologic materials affected how long debris-flow activity persisted, and the timing of debris flows varied within different rainfall regimes. A second, later period of increased debris flow susceptibility between 2.2 and 10 years after fires is indicated by the remaining 8 percent of events, which occurred primarily in forested terrains and initiated largely through landslide processes. The short time period between fire and debris-flow response within the first 1.5 years after ignition, and the longer-term response between 2.2 and 10 years after fire, demonstrate the necessity of both rapid and long-term reactions by land managers and emergency-response agencies to mitigate hazards from debris flows from recently burned areas in the western U.S.

  4. Characteristics of Air Entrainment in Hydraulic Jump

    Science.gov (United States)

    Albarkani, M. S. S.; Tan, L. W.; Al-Gheethi, A.

    2018-04-01

    The characteristics of hydraulic jump, especially the air entrainment within jump is still not properly understood. Therefore, the current work aimed to determine the size and number of air entrainment formed in hydraulic jump at three different Froude numbers and to obtain the relationship between Froude number with the size and number of air entrainment in hydraulic jump. Experiments of hydraulic jump were conducted in a 10 m long and 0.3 m wide Armfield S6MKII glass-sided tilting flume. Hydraulic jumps were produced by flow under sluice gate with varying Froude number. The air entrainment of the hydraulic jump was captured with a Canon Power Shot SX40 HS digital camera in video format at 24 frames per second. Three discharges have been considered, i.e. 0.010 m3/s, 0.011 m3/s, and 0.013 m3/s. For hydraulic jump formed in each discharge, 32 frames were selected for the purpose of analysing the size and number of air entrainment in hydraulic jump. The results revealed that that there is a tendency to have greater range in sizes of air bubbles as Fr1 increases. Experiments with Fr1 = 7.547. 7.707, and 7.924 shown that the number of air bubbles increases exponentially with Fr1 at a relationship of N = 1.3814 e 0.9795Fr1.

  5. Measurements of air entrainment by vertical plunging liquid jets

    Science.gov (United States)

    El Hammoumi, M.; Achard, J. L.; Davoust, L.

    2002-06-01

    This paper addresses the issue of the air-entrainment process by a vertical plunging liquid jet. A non-dimensional physical analysis, inspired by the literature on the stability of free jets submitted to an aerodynamic interaction, was developed and yielded two correlation equations for the laminar and the turbulent plunging jets. These correlation equations allow the volumetric flow rate of the air carryunder represented by the Weber number of entrainment We n to be predicted. The plunging jets under consideration issued from circular tubes long enough to achieve a fully developed flow at the outlet. A sensitive technique based on a rising soap meniscus was developed to measure directly the volumetric flow rate of the air carryunder. Our data are compared with other experimental data available in the literature; they also stand as a possible database for future theoretical modelling.

  6. Measurements of air entrainment by vertical plunging liquid jets

    Energy Technology Data Exchange (ETDEWEB)

    El Hammoumi, M. [Faculte des Sciences et Techniques, Departement de Physique, Laboratoire de Mecanique Appliquee, Fes (Morocco); Achard, J.L.; Davoust, L. [Laboratoire des Ecoulements Geophysiques et Industriels (LEGI), Grenoble (France)

    2002-06-01

    This paper addresses the issue of the air-entrainment process by a vertical plunging liquid jet. A non-dimensional physical analysis, inspired by the literature on the stability of free jets submitted to an aerodynamic interaction, was developed and yielded two correlation equations for the laminar and the turbulent plunging jets. These correlation equations allow the volumetric flow rate of the air carryunder represented by the Weber number of entrainment We{sub n} to be predicted. The plunging jets under consideration issued from circular tubes long enough to achieve a fully developed flow at the outlet. A sensitive technique based on a rising soap meniscus was developed to measure directly the volumetric flow rate of the air carryunder. Our data are compared with other experimental data available in the literature; they also stand as a possible database for future theoretical modelling. (orig.)

  7. A study of the flow field surrounding interacting line fires

    Science.gov (United States)

    Trevor Maynard; Marko Princevac; David R. Weise

    2016-01-01

    The interaction of converging fires often leads to significant changes in fire behavior, including increased flame length, angle, and intensity. In this paper, the fluid mechanics of two adjacent line fires are studied both theoretically and experimentally. A simple potential flow model is used to explain the tilting of interacting flames towards each other, which...

  8. Entraining the Brain: Applications to Language Research and Links to Musical Entrainment

    Directory of Open Access Journals (Sweden)

    Usha Goswami

    2012-09-01

    Full Text Available Clayton’s paper provides a clear and accessible summary of the significance of entrainment for music making, and for human behaviour in general. He notes the central role of metrical structure in musical entrainment, the possible role of oscillatory neural activity, and the core notion of phase alignment. Here I show how these same factors are central to speech processing by the human brain. I argue that entrainment to metrical structure is core to linguistic as well as musical human behaviour. I illustrate this view using entrainment data from developmental dyslexia. The core role of entrainment in efficient speech processing suggests that language difficulties in childhood may benefit from music-based remediation that focuses on multi-modal rhythmic entrainment. Alignment of linguistic and musical metrical structure seems likely to be fundamental to successful remediation.

  9. Noninvasive CPAP with face mask: comparison among new air-entrainment masks and the Boussignac valve.

    Science.gov (United States)

    Mistraletti, Giovanni; Giacomini, Matteo; Sabbatini, Giovanni; Pinciroli, Riccardo; Mantovani, Elena S; Umbrello, Michele; Palmisano, Debora; Formenti, Paolo; Destrebecq, Anne L L; Iapichino, Gaetano

    2013-02-01

    The performances of 2 noninvasive CPAP systems (high flow and low flow air-entrainment masks) were compared to the Boussignac valve in 3 different scenarios. Scenario 1: pneumatic lung simulator with a tachypnea pattern (tidal volume 800 mL at 40 breaths/min). Scenario 2: Ten healthy subjects studied during tidal breaths and tachypnea. Scenario 3: Twenty ICU subjects enrolled for a noninvasive CPAP session. Differences between set and effective CPAP level and F(IO(2)), as well as the lowest airway pressure and the pressure swing around the imposed CPAP level, were analyzed. The lowest airway pressure and swing were correlated to the pressure-time product (area of the airway pressure curve below the CPAP level) measured with the simulator. P(aO(2)) was a subject's further performance index. Lung simulator: Boussignac F(IO(2)) was 0.54, even if supplied with pure oxygen. The air-entrainment masks had higher swing than the Boussignac (P = .007). Pressure-time product correlated better with pressure swing (Spearman correlation coefficient [ρ] = 0.97) than with lowest airway pressure (ρ = 0.92). In healthy subjects, the high-flow air-entrainment mask showed lower difference between set and effective F(IO(2)) (P mask had lower swing than the Boussignac valve (P = .03) with similar P(aO(2)) increase. High-flow air-entrainment mask showed the best performance in human subjects. During high flow demand, the Boussignac valve delivered lower than expected F(IO(2)) and showed higher dynamic hyper-pressurization than the air-entrainment masks. © 2013 Daedalus Enterprises.

  10. Supercavitating flow around high-speed underwater projectile near free surface induced by air entrainment

    Directory of Open Access Journals (Sweden)

    Chang Xu

    2018-03-01

    Full Text Available Cavitating flow near free surface is a complicated issue and may provide new inspiration on high-speed surface cruising. This study observes stable supercavitating flow as a new phenomenon in a launch experiment of axisymmetric projectile when the upper side of the projectile coincides with the free surface. A numerical approach is established using large eddy-simulation and volume-of-fluid methods, and good agreements are achieved between numerical and experimental results. Supercavity formation mechanism is revealed by analyzing the experiment photographs and the iso-surface of 90% water volume fraction in numerical results. The entrainment of a large amount of air into the cavity can cause the pressure inside the cavity to similarly increase with the pressure outside the cavity, which makes the actual cavitation number close to zero and is similar to supercavitation. Cases with various headforms of the projectile and cavitation numbers on the cavitating flow, as well as the drag reduction effects are further examined. Results indicate that the present strategy near the free surface could possibly be a new effective approach for high-speed cruising after vigorous design optimization in the future.

  11. Entrainment and mixing in lock-exchange gravity currents using simultaneous velocity-density measurements

    Science.gov (United States)

    Balasubramanian, Sridhar; Zhong, Qiang

    2018-05-01

    Gravity currents modify their flow characteristics by entraining ambient fluid, which depends on a variety of governing parameters such as the initial density, Δρ, the total initial height of the fluid, H, and the slope of the terrain, α, from where it is released. It is imperative to study the entrainment dynamics of a gravity current in order to have a clear understanding of mixing transitions that govern the flow physics, the velocity mixing layer thickness, δu, and the density mixing layer thickness, δρ. Experiments were conducted in a lock-exchange facility in which the dense fluid was separated from the ambient lighter fluid using a gate. As the gate is released instantaneously, an energy conserving gravity current is formed, for which the only governing parameter is the Reynolds number defined as R e =U/h ν , where U is the front velocity of the gravity current and h is the height of the current. In our study, the bulk Richardson number (inverse of Froude number, Fr), Rib = g/'H Ub2 = 1, takes a constant value for all the experiments, with Ub being the bulk velocity of the current defined as Ub = √{g'H }. Simultaneous particle image velocimetry and planar laser induced fluorescence measurement techniques are employed to get the velocity and density statistics. Using the buoyancy conservation equation, a new flux-based method was formulated for calculating the entrainment coefficient, EF, near the front and head of the propagating gravity current for a Reynolds number range of Re ≈ 485-12 270 used in our experiments. At the head of the current, the results show a mixing transition at Re ≈ 2700 that is attributed to the flow transitioning from weak Holmboe waves to Kelvin-Helmholtz instabilities, in the form of Kelvin-Helmholtz vortex rolls. Following this mixing transition, the entrainment coefficient continued to increase with increasing Reynolds number owing to the occurrence of three-dimensional Kelvin-Helmholtz billows that promote further

  12. Better Fire Emissions Estimates for Tricky Species Illustrated with a Simple Empirical Burn-to-Sample Plume Mode

    Science.gov (United States)

    Chatfield, R. B.; Andreae, M. O.; Lareau, N.

    2017-12-01

    Methodologies for estimating emission factors (EFs) and broader emission relationship (ERs) (for e.g., O3 production or aerosol absorption) have been difficult to make accurate and convincing; this is largely due to non-fire effects on both CO2 and also fire-emitted trace species. We present a new view of these multiple effects as they affect downwind tracer samples observed by aircraft in NASA's ARCTAS and SEAC4RS airborne missions. This view leads to our method for estimates of ERs and EFs that allow spatially detailed views focusing on individual samples, a Mixed Effects Emission Ratio Technique (MERET). We concentrate on presenting a generalized viewpoint: a simple idealized model of a fire plume entraining air from near-flames upward and then outward to a sampling point, a view base on observations of typical situations. Actual evolution of a plume can depend intricately on the fully history of entrainment, entraining concentration levels of CO2 and tracer species, and mixing. Observations suggest that our simple plume model with just two (analyzed) values for entrained CO2 and one or potentially two values for environmental concentrations for each tracer can serve surprisingly well for mixed-effects regression estimates. Such details appears imperative for long-lived gases like CH4, CO, and N2O. In particular, it is difficult to distinguish fire-sourced emissions from air entrained near the flames, entrained in a way proportional to fire intensity. These entraining concentrations may vary significantly from those later in plume evolution. In addition, such detail also highlights behavior of emissions that react on the path to sampling, e.g. fire-sourced or entrained urban NOx. Some caveats regarding poor sampling situations, and some warning signs, based on this empirical plume description and on MERET analyses, are demonstrated. Some information is available when multiple tracers are analyzed. MERET estimates for ERs of short and these long-lived species are

  13. Impact of entrainment and impingement on fish populations in the Hudson River estuary. Volume I. Entrainment-impact estimates for six fish populations inhabiting the Hudson River estuary

    International Nuclear Information System (INIS)

    Boreman, J.; Barnthouse, L.W.; Vaughn, D.S.; Goodyear, C.P.; Christensen, S.W.; Kumar, K.D.; Kirk, B.L.; Van Winkle, W.

    1982-01-01

    This volume is concerned with the estimation of the direct (or annual) entrainment impact of power plants on populations of striped bass, white perch, Alosa spp. (blueback herring and alewife), American shad, Atlantic tomcod, and bay anchovy in the Hudson River estuary. Entrainment impact results from the killing of fish eggs, larvae, and young juveniles that are contained in the cooling water cycled through a power plant. An Empirical Transport Model (ETM) is presented as the means of estimating a conditional entrainment mortality rate (defined as the fraction of a year class which would be killed due to entrainment in the absence of any other source of mortality). Most of this volume is concerned with the estimation of several parameters required by the ETM: physical input parameters (e.g., power-plant withdrawal flow rates); the longitudinal distribution of ichthyoplankton in time and space; the duration of susceptibility of the vulnerable organisms; the W-factors, which express the ratios of densities of organisms in power plant intakes to densities of organisms in the river; and the entrainment mortality factors (f-factors), which express the probability that an organism will be killed if it is entrained. Once these values are obtained, the ETM is used to estimate entrainment impact for both historical and projected conditions

  14. Entrainment and deposition studies in two-phase cross flow: comparison between air-water and steam-water in a square horizontal duct. Technical report (final)

    International Nuclear Information System (INIS)

    Berryman, R.J.; Ralph, J.C.; Wade, C.D.

    1981-03-01

    Air-water simulation studies of two phase steam water flow relevant to the upper plenum of a PWR during reflood situations have recently been undertaken at Harwell for the US Nuclear Regulatory Commission. In order to give confidence that the simulation fluids were capable of modelling the important features of the actual system, a relatively basic comparison experiment has been carried out. Water entrainment and deposition tests have been carried out on a pair of 2.5 cm diameter vertical rods mounted in a cross flow of steam or air in a 10.2 cm x 10.2 cm tunnel. The air and steam systems exhibited similar characteristics to one another. A 'critical' film flowrate was identified for the rods which, once reached, either by injection through the sinters or by entrainment from the main two phase stream, was not exceeded with further water addition. The 'critical' film flowrate decreased with increase of cross flow velocity and was lower for air than steam at the same velocity. The results from the air and steam tests were found to be reasonably well correlated on the basis of the cross flow momentum flux of the air or steam

  15. Experimental study on combustion characteristics of sodium fire in a columnar flow

    International Nuclear Information System (INIS)

    Zhang Zhigang; Peng Kangwei; Guo Ming; Huo Yan

    2014-01-01

    In the operation of the sodium-cooled fast reactor, the accident caused by the leakage and combustion of liquid sodium is common and frequent in sodium-related facilities. This paper is based on an experimental study of sodium fire in a columnar flow, which was carried out to focus on the burning characteristics by analyzing the temperature fields in the burner. The injection of 200°C liquid sodium with the flux of 0.5 m 3 /h was poured into a 7.9 m 3 volume stainless steel cylindrical burner to shape a sodium fire, and the data of temperature fields in the burner have been collected by dozens of thermocouples which are laid in the combustion space and sodium collection plate. These results show that the sodium fire in a columnar flow is composed of the foregoing centered columnar fire, the subsequent spray fire caused by atomization and the pool fire on the collection plate. The temperature close to the burning sodium flow maximally reaches up to 950°C. The radial temperatures apart from the sodium flow are relatively low and generally about 200°C, and maximally just 300°C even when close to the sodium collection plate. The maximum temperature of the burning sodium dropping on the collection plate rises in the center of plate, about 528°C. This study is helpful to evaluate the combustion characteristics, formation process and composing forms of the sodium fire in the sodium-related facilities. (author)

  16. Drop size measurements and entrainment in APR1400 during LBLOCA reflood phase

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eo Hwak

    2010-02-15

    A study has been performed to investigate droplet size in the nuclear reactor of APR1400 during LBLOCA reflood phase and to develop droplet entrainment and deposition models for SPACE (Safety and Performance CodE) which is a safety analysis tool for PWR being developed in Korea. A freezing technique for measuring the size of droplets was developed to obtain the droplet size distribution in horizontal annular flow in a pipe with a 37.1 mm diameter. Droplets are frozen by using an extremely low temperature nitrogen gas with liquid film extraction. They are then photographed with a microscope and a CCD camera and measured by means of an image process. The results are compared with various experimental data. The droplet sizes measured by the freezing technique are comparable with those measured by other methods at a high superficial air velocity (of 50 m/s). However, because of the film extraction problem, the droplet sizes measured at a low superficial air velocity of less than 40 m/s are higher than those measured by other methods. A present method suggested for predicting the Sauter mean diameter is based on the maximum droplet size correlation for the experimental data, with and without liquid film extraction. The average droplet size is remarkably smaller downstream of the liquid film extractor because large droplets from the liquid film are excluded. In order to understand and to predict a heat transfer between superheated steam and droplets properly during reflood phase of LBLOCA, it is very important to measure broken droplet sizes by spacer grids. A study, therefore, has been performed to investigate droplet size in rod bundles with spacer grids and to develop a spacer grid droplet breakup model for safety analysis codes. Experiments were conducted with liquid droplets (SMD of 300∼700 μm) and various spacer grids at superficial air velocity of 10 m/s and 20 m/s based on FLECHT SEASET. The test channel and the grids were heated to 150 .deg. C to prevent

  17. Drop size measurements and entrainment in APR1400 during LBLOCA reflood phase

    International Nuclear Information System (INIS)

    Lee, Eo Hwak

    2010-02-01

    A study has been performed to investigate droplet size in the nuclear reactor of APR1400 during LBLOCA reflood phase and to develop droplet entrainment and deposition models for SPACE (Safety and Performance CodE) which is a safety analysis tool for PWR being developed in Korea. A freezing technique for measuring the size of droplets was developed to obtain the droplet size distribution in horizontal annular flow in a pipe with a 37.1 mm diameter. Droplets are frozen by using an extremely low temperature nitrogen gas with liquid film extraction. They are then photographed with a microscope and a CCD camera and measured by means of an image process. The results are compared with various experimental data. The droplet sizes measured by the freezing technique are comparable with those measured by other methods at a high superficial air velocity (of 50 m/s). However, because of the film extraction problem, the droplet sizes measured at a low superficial air velocity of less than 40 m/s are higher than those measured by other methods. A present method suggested for predicting the Sauter mean diameter is based on the maximum droplet size correlation for the experimental data, with and without liquid film extraction. The average droplet size is remarkably smaller downstream of the liquid film extractor because large droplets from the liquid film are excluded. In order to understand and to predict a heat transfer between superheated steam and droplets properly during reflood phase of LBLOCA, it is very important to measure broken droplet sizes by spacer grids. A study, therefore, has been performed to investigate droplet size in rod bundles with spacer grids and to develop a spacer grid droplet breakup model for safety analysis codes. Experiments were conducted with liquid droplets (SMD of 300∼700 μm) and various spacer grids at superficial air velocity of 10 m/s and 20 m/s based on FLECHT SEASET. The test channel and the grids were heated to 150 .deg. C to prevent

  18. Ash transformation in suspension fired boilers co-firing coal and straw

    DEFF Research Database (Denmark)

    Zheng, Yuanjing; Jensen, Peter Arendt; Jensen, Anker Degn

    The properties of the ash from co-firing of coal and straw have a large influence on boiler operation, flue gas cleaning equipment and appropriate utilization of the fly ash. A study on the fuel composition and local conditions influence on fly ash properties has been done by making entrained flo...

  19. Entrainment of droplets during the reflood phase of a LOCA and the influence of the channel geometry

    International Nuclear Information System (INIS)

    van der Molen, S.B.; Galjee, F.W.B.M.

    1979-01-01

    This paper describes the different reflood phenomena and the most relevant appearing two phase flow patterns such as the inverted annular, the annular and dispersed flow regimes and the transition between the different regimes. From high speed films it is clear that the onset of entrainment in case of the liquid column type quench mode occurs simultaneously with the transition of churn flow to a dispersed flow whereas in case of the dryout type quench mode with an annular flow at the quench front, the onset of entrainment is caused by the interaction of the vapor flow on the liquid film flow. 14 refs

  20. Fire flow water consumption in sprinklered and unsprinklered buildings an assessment of community impacts

    CERN Document Server

    Code Consultants, Inc.

    2012-01-01

    Fire Flow Water Consumption in Sprinklered and Unsprinklered Buildings offers a detailed analysis for calculating the fire water demand required in buildings with existing and non-existant sprinkler systems. The installation of automatic sprinkler systems can significantly reduce the amount of water needed during a fire, but it requires water for commissioning, inspection, testing, and maintenance (CITM). This book provides an estimate of fire water used under both fire conditions, including CITM, to allow communities to develop fire water fees for both sprinklered and unsprinklered buildings that are proportional to the anticipated fire water usage. The types of buildings analyzed include residential (family dwellings as well as those up to four stories in height), business, assembly, institutional, mercantile, and storage facilities. Water volume was studied using guidelines from the International Code Council, the National Fire Protection Association, and the Insurance Services Office. Fire Flow Water Cons...

  1. Entrainment separator performance

    International Nuclear Information System (INIS)

    First, M.W.; Leith, D.

    1976-01-01

    Clean and dust-loaded ACS entrainment separators mounted upstream of HEPA filters were exposed to a combination of fine water mist and steam at about 70 0 C from one to four hours. In every trial, the ACS entrainment separator prevented measurable deterioration of performance in the following HEPA filter. Droplet size-efficiency evaluation of the ACS entrainment separators showed that, within the accuracy of the measurements, they meet all service requirements and are fully equal to the best separator units available for service on pressurized water reactors

  2. Flash pyrolysis of agricultural residues using a plasma heated laminar entrained flow reactor

    International Nuclear Information System (INIS)

    Xiu Shuangning; Yi Weiming; Li Baoming

    2005-01-01

    In order to study the volatilization characteristics of biomass particles at flash heating rates, a plasma heated laminar entrained flow reactor (PHLEFR) was designed and built in our lab. Two agricultural residues, wheat straw and corn stalk, were chosen as feedstock for pyrolysis which were conducted on the PHLEFR with the aim of determining the extent of thermal decomposition at high heating rate (more than 10 4o Cs -1 ). Based on the experimental data, a first order kinetic model was introduced and the relevant kinetic parameters (apparent active energy and apparent frequency factor) were determined for the two straws: E=31.51kJmol -1 , A=1028s -1 (wheat straw) and E=33.74kJmol -1 , A=1013s -1 (corn stalk). The predicted conversion of the fitted model to the experimental data provided general agreements when one considered the experimental errors

  3. Development of advanced air-blown entrained-flow two-stage bituminous coal IGCC gasifier

    Directory of Open Access Journals (Sweden)

    Abaimov Nikolay A.

    2017-01-01

    Full Text Available Integrated gasification combined cycle (IGCC technology has two main advantages: high efficiency, and low levels of harmful emissions. Key element of IGCC is gasifier, which converts solid fuel into a combustible synthesis gas. One of the most promising gasifiers is air-blown entrained-flow two-stage bituminous coal gasifier developed by Mitsubishi Heavy Industries (MHI. The most obvious way to develop advanced gasifier is improvement of commercial-scale 1700 t/d MHI gasifier using the computational fluid dynamics (CFD method. Modernization of commercial-scale 1700 t/d MHI gasifier is made by changing the regime parameters in order to improve its cold gas efficiency (CGE and environmental performance, namely H2/CO ratio. The first change is supply of high temperature (900°C steam in gasifier second stage. And the second change is additional heating of blast air to 900°C.

  4. Electrification of particulate entrained fluid flows—Mechanisms, applications, and numerical methodology

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Wei [School of Energy and Power Engineering, Wuhan University of Technology, Wuhan, Hubei, 430063 (China); School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi, 710049 (China); Gu, Zhaolin, E-mail: guzhaoln@mail.xjtu.edu.cn [School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi, 710049 (China)

    2015-10-28

    Particulates in natural and industrial flows have two basic forms: liquid (droplet) and solid (particle). Droplets would be charged in the presence of the applied electric field (e.g. electrospray). Similar to the droplet charging, particles can also be charged under the external electric field (e.g. electrostatic precipitator), while in the absence of external electric field, tribo-electrostatic charging is almost unavoidable in gas–solid two-phase flows due to the consecutive particle contacts (e.g. electrostatic in fluidized bed or wind-blown sand). The particle charging may be beneficial, or detrimental. Although electrostatics in particulate entrained fluid flow systems have been so widely used and concerned, the mechanisms of particulate charging are still lack of a thorough understanding. The motivation of this review is to explore a clear understanding of particulate charging and movement of charged particulate in two-phase flows, by summarizing the electrification mechanisms, physical models of particulate charging, and methods of charging/charged particulate entrained fluid flow simulations. Two effective methods can make droplets charged in industrial applications: corona charging and induction charging. The droplet charge to mass ratio by corona charging is more than induction discharge. The particle charging through collisions could be attributed to electron transfer, ion transfer, material transfer, and/or aqueous ion shift on particle surfaces. The charges on charged particulate surface can be measured, nevertheless, the charging process in nature or industry is difficult to monitor. The simulation method might build a bridge of investigating from the charging process to finally charged state on particulate surface in particulate entrained fluid flows. The methodology combining the interface tracking under the action of the applied electric with the fluid flow governing equations is applicable to the study of electrohydrodynamics problems. The

  5. Electrification of particulate entrained fluid flows—Mechanisms, applications, and numerical methodology

    International Nuclear Information System (INIS)

    Wei, Wei; Gu, Zhaolin

    2015-01-01

    Particulates in natural and industrial flows have two basic forms: liquid (droplet) and solid (particle). Droplets would be charged in the presence of the applied electric field (e.g. electrospray). Similar to the droplet charging, particles can also be charged under the external electric field (e.g. electrostatic precipitator), while in the absence of external electric field, tribo-electrostatic charging is almost unavoidable in gas–solid two-phase flows due to the consecutive particle contacts (e.g. electrostatic in fluidized bed or wind-blown sand). The particle charging may be beneficial, or detrimental. Although electrostatics in particulate entrained fluid flow systems have been so widely used and concerned, the mechanisms of particulate charging are still lack of a thorough understanding. The motivation of this review is to explore a clear understanding of particulate charging and movement of charged particulate in two-phase flows, by summarizing the electrification mechanisms, physical models of particulate charging, and methods of charging/charged particulate entrained fluid flow simulations. Two effective methods can make droplets charged in industrial applications: corona charging and induction charging. The droplet charge to mass ratio by corona charging is more than induction discharge. The particle charging through collisions could be attributed to electron transfer, ion transfer, material transfer, and/or aqueous ion shift on particle surfaces. The charges on charged particulate surface can be measured, nevertheless, the charging process in nature or industry is difficult to monitor. The simulation method might build a bridge of investigating from the charging process to finally charged state on particulate surface in particulate entrained fluid flows. The methodology combining the interface tracking under the action of the applied electric with the fluid flow governing equations is applicable to the study of electrohydrodynamics problems. The

  6. Entrainer selection for the synthesis of fatty acid esters by entrainer-based reactive distillation

    NARCIS (Netherlands)

    Jong, de M.C.; Zondervan, E.; Dimian, A.C.; Haan, de A.B.

    2010-01-01

    In this research it is demonstrated that, due to the similarities between Entrainer-based Reactive Distillation and azeotropic distillation, the same selection rules can be applied to select a suitable entrainer. From a list of suitable entrainers for the azeotropic distillation of isopropanol and

  7. PTV analysis of the entrained air into the diesel spray at high-pressure injection

    Science.gov (United States)

    Toda, Naoki; Yamashita, Hayato; Mashida, Makoto

    2014-08-01

    In order to clarify the effect of high-pressure injection on soot reduction in terms of the air entrainment into spray, the air flow surrounding the spray and set-off length indicating the distance from the nozzle tip to the flame region in diffusion diesel combustion were investigated using 300MPa injection of a multi-hole injector. The measurement of the air entrainment flow was carried out at non-evaporating condition using consecutive PTV (particle tracking velocimetry) method with a high-speed camera and a high-frequency pulse YAG laser. The set-off length was measured at highpressure and high-temperature using the combustion bomb of constant volume and optical system of shadow graph method. And the amount of air entrainment into spray until reaching set-off length in diffusion combustion was studied as a factor of soot formation.

  8. Optimizing the Entrainment Geometry of a Dry Powder Inhaler: Methodology and Preliminary Results.

    Science.gov (United States)

    Kopsch, Thomas; Murnane, Darragh; Symons, Digby

    2016-11-01

    For passive dry powder inhalers (DPIs) entrainment and emission of the aerosolized drug dose depends strongly on device geometry and the patient's inhalation manoeuvre. We propose a computational method for optimizing the entrainment part of a DPI. The approach assumes that the pulmonary delivery location of aerosol can be determined by the timing of dose emission into the tidal airstream. An optimization algorithm was used to iteratively perform computational fluid dynamic (CFD) simulations of the drug emission of a DPI. The algorithm seeks to improve performance by changing the device geometry. Objectives were to achieve drug emission that was: A) independent of inhalation manoeuvre; B) similar to a target profile. The simulations used complete inhalation flow-rate profiles generated dependent on the device resistance. The CFD solver was OpenFOAM with drug/air flow simulated by the Eulerian-Eulerian method. To demonstrate the method, a 2D geometry was optimized for inhalation independence (comparing two breath profiles) and an early-bolus delivery. Entrainment was both shear-driven and gas-assisted. Optimization for a delay in the bolus delivery was not possible with the chosen geometry. Computational optimization of a DPI geometry for most similar drug delivery has been accomplished for an example entrainment geometry.

  9. An applied model for the height of the daytime mixed layer and the entrainment zone

    DEFF Research Database (Denmark)

    Batchvarova, E.; Gryning, Sven-Erik

    1994-01-01

    A model is presented for the height of the mixed layer and the depth of the entrainment zone under near-neutral and unstable atmospheric conditions. It is based on the zero-order mixed layer height model of Batchvarova and Gryning (1991) and the parameterization of the entrainment zone depth......-layer height: friction velocity, kinematic heat flux near the ground and potential temperature gradient in the free atmosphere above the entrainment zone. When information is available on the horizontal divergence of the large-scale flow field, the model also takes into account the effect of subsidence...

  10. Generation of entrained droplets from an imitated disturbance wave and their deposition on the wall

    International Nuclear Information System (INIS)

    Fukano, T.; Inatomi, T.; Matsuzawa, Y.; Yoshida, T.; Uchimichi, N.

    2003-01-01

    In the present experiment, an isokinetic sampling probe technique was used for the measurement of the local droplet flow rate generated from an imitated disturbance wave, which was constructed by injecting liquid through a slit mounted on the bottom wall of a horizontal rectangular duct. The experimental data on the distribution of entrained droplets and their deposition on the duct wall are presented. As a result, it is clarified that the droplet generation is periodic and the distribution of the droplet flow rate is not uniform in both axial and height directions. And accordingly the droplet flow is fundamentally unsteady. Furthermore, the correlation of the entrainment fraction proposed by Paleev-Filippovich is superior to that by others. (orig.)

  11. Stochastic study on entrainment of floating particles with intake of cooling water of a power plant

    International Nuclear Information System (INIS)

    Kadoyu, Masatake; Wada, Akira

    1979-01-01

    The mortality of ichthyoplanktons, contained in the sea water passing through the cooling water systems of a power plant, may be associated with rising temperature and mechanical effect. In this study, the range and the rate of entrainment of the organisms like ichthyoplanktons floating in the sea caused by the intake of cooling water were stochastically investigated by simulating the average current as well as the flow caused by the intake of water and by taking into consideration random velocity fluctuation without these flows, using a mathematical model. An intake was set along the straight coastline in semi-infinite sea, and the rate of inflow of particles into the intake was simulated by a mathematical model. In the numerical simulation, the average flow as coastal current component and the flow caused by the intake of water were obtained with the hydrodynamic equations of motion and continuity, and the rate of entrainment of floating particles was examined by giving turbulence to the particles in the sea and by calculating the position of each particle every moment. The results are as follows; 1) The range of entrainment of floating particles by the intake of cooling water and its probability were obtained in consideration of the flow rate of cooling water, coast current velocity and diffusion coefficient as parameters. 2) The extent of inflow of floating particles considerably varied with tidal amplitude, diffusion coefficient and the flow rate of cooling water in the sea where the coastal flow has clear periodicity. 3) The extent of entrainment was considerably influenced by the steady current velocity, the velocity distribution in offshore direction and the intake volume in the sea where periodicity is not observed. (Nakai, Y.)

  12. Inclined gravity currents filling basins: The influence of Reynolds number on entrainment into gravity currents

    Science.gov (United States)

    Hogg, Charlie A. R.; Dalziel, Stuart B.; Huppert, Herbert E.; Imberger, Jörg

    2015-09-01

    In many important natural and industrial systems, gravity currents of dense fluid feed basins. Examples include lakes fed by dense rivers and auditoria supplied with cooled air by ventilation systems. As we will show, the entrainment into such buoyancy driven currents can be influenced by viscous forces. Little work, however, has examined this viscous influence and how entrainment varies with the Reynolds number, Re. Using the idea of an entrainment coefficient, E, we derive a mathematical expression for the rise of the front at the top of the dense fluid ponding in a basin, where the horizontal cross-sectional area of the basin varies linearly with depth. We compare this expression to experiments on gravity currents with source Reynolds numbers, Res, covering the broad range 100 < Res < 1500. The form of the observed frontal rises was well approximated by our theory. By fitting the observed frontal rises to the theoretical form with E as the free parameter, we find a linear trend for E(Res) over the range 350 < Res < 1100, which is in the transition to turbulent flow. In the experiments, the entrainment coefficient, E, varied from 4 × 10-5 to 7 × 10-2. These observations show that viscous damping can be a dominant influence on gravity current entrainment in the laboratory and in geophysical flows in this transitional regime.

  13. Numerical Study to Find Mechanisms Behind the Spread of Hot Gases and Smoke in a Multi-room Fire

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Gong Hee [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2016-10-15

    According to the international fire safety analysis studies, fire contributes significantly to the overall core damage frequency (CDF) for both existing and new nuclear power plants. Fire simulation models have been developed as analytical tools for a performance-based fire safety assessment. The use of calculated predictions could be considered, on the one hand, for improvements and upgrades of the fire protection by the licensees and, on the other hand, as a tool for reproducible and clearly understandable estimations in assessing the available and/or foreseen fire protection measures by the regulatory authority. In this study, in order to evaluate the prediction performance of fire simulation model for the spread of hot gases and smoke in a multi-room fire, calculations were conducted with Fire Dynamic Simulator (FDS) 6.4. In this study, in order to evaluate the prediction performance of fire simulation model for the spread of hot gases and smoke in a multi-room fire, calculations were conducted with FDS 6.4. The predicted results were compared with measured data (PRS{sub D}1) obtained from PRISME Door test series. The major conclusion could be summarized in fire (source) room, buoyant gases moved up to ceiling in fire plume and ceiling jet spread radially until confined by room partition. Additionally, because plume entrained surrounding air, relatively cold flow moved from target room toward fire (source) room through a lower part of open door and Although FDS could give the meaningful information to understand the thermal-flow pattern in the under-ventilated fire condition, it still had the limitation (for example, over-estimation of flame temperature) and then showed a certain level of uncertainty in the calculation result.

  14. Ignition behaviour of different rank coals in an entrained flow reactor

    Energy Technology Data Exchange (ETDEWEB)

    J. Faundez; A. Arenillas; F. Rubiera; X. Garcia; A.L. Gordon; J.J. Pis [Instituto Nacional del Carbon (INCAR), Oviedo (Spain)

    2005-12-01

    An experimental study to determine the temperature and mechanism of coal ignition was carried out by using an entrained flow reactor (EFR) at relatively high coal feed rates (0.5 g min{sup -1}). Seven coals ranging in rank from subbituminous to semianthracite, were tested and the evolved gases (O{sub 2}, CO, CO{sub 2}, NO) were measured continuously. The ignition temperature was evaluated from the gas evolution profiles, and it was found to be inversely correlated to the reactivity of the coal, as reflected by the increasing values of the ignition temperature in the sequence: subbituminous, high volatile bituminous, low volatile bituminous and semianthracite coals. The mechanism of ignition varied from a heterogeneous mechanism for subbituminous, low volatile bituminous and semianthracite coals, to a homogeneous mechanism for high volatile bituminous coals. A thermogravimetric analyser (TGA) was also used to evaluate coal ignition behaviour. Both methods, TGA and EFR, were in agreement as regards the mechanism of coal ignition. From the SEM micrographs of the coal particles retrieved from the cyclone, it was possible to observe the external appearance of the particles before, during and after ignition. The micrographs confirmed the mechanism deduced from the gas profiles. 23 refs., 5 figs., 1 tab.

  15. Computer Self-Efficacy, Competitive Anxiety and Flow State: Escaping from Firing Online Game

    Science.gov (United States)

    Hong, Jon-Chao; Pei-Yu, Chiu; Shih, Hsiao-Feng; Lin, Pei-Shin; Hong, Jon-Chao

    2012-01-01

    Flow state in game playing affected by computer self-efficacy and game competitive anxiety was studied. In order to examine the effect of those constructs with high competition, this study select "Escaping from firing online game" which require college students to escape from fire and rescue people and eliminate the fire damage along the way of…

  16. Creepy landscapes : river sediment entrainment develops granular flow rheology on creeping bed.

    Science.gov (United States)

    Prancevic, J.; Chatanantavet, P.; Ortiz, C. P.; Houssais, M.; Durian, D. J.; Jerolmack, D. J.

    2015-12-01

    To predict rates of river sediment transport, one must first address the zeroth-order question: when does sediment move? The concept and determination of the critical fluid shear stress remains hazy, as observing particle motion and determining sediment flux becomes increasingly hard in its vicinity. To tackle this problem, we designed a novel annular flume experiment - reproducing an infinite river channel - where the refractive index of particles and the fluid are matched. The fluid is dyed with a fluorescent powder and a green laser sheet illuminates the fluid only, allowing us to observe particle displacements in a vertical plane. Experiments are designed to highlight the basic granular interactions of sediment transport while suppressing the complicating effects of turbulence; accordingly, particles are uniform spheres and Reynolds numbers are of order 1. We have performed sediment transport measurements close to the onset of particle motion, at steady state, and over long enough time to record averaged rheological behavior of particles. We find that particles entrained by a fluid exhibit successively from top to bottom: a suspension regime, a dense granular flow regime, and - instead of a static bed - a creeping regime. Data from experiments at a range of fluid stresses can be collapsed onto one universal rheologic curve that indicates the effective friction is a monotonic function of a dimensionless number called the viscous number. These data are in remarkable agreement with the local rheology model proposed by Boyer et al., which means that dense granular flows, suspensions and bed-load transport are unified under a common frictional flow law. Importantly, we observe slow creeping of the granular bed even in the absence of bed load, at fluid stresses that are below the apparent critical value. This last observation challenges the classical definition of the onset of sediment transport, and points to a continuous transition from quasi-static deformation to

  17. Bed-material entrainment potential, Roaring Fork River at Basalt, Colorado

    Science.gov (United States)

    Elliott, John G.

    2002-01-01

    The Roaring Fork River at Basalt, Colorado, has a frequently mobile streambed composed of gravel, cobbles, and boulders. Recent urban and highway development on the flood plain, earlier attempts to realign and confine the channel, and flow obstructions such as bridge openings and piers have altered the hydrology, hydraulics, sediment transport, and sediment deposition areas of the Roaring Fork. Entrainment and deposition of coarse sediment on the streambed and in large alluvial bars have reduced the flood-conveying capacity of the river. Previous engineering studies have identified flood-prone areas and hazards related to inundation and high streamflow velocity, but those studies have not evaluated the potential response of the channel to discharges that entrain the coarse streambed. This study builds upon the results of earlier flood studies and identifies some potential areas of concern associated with bed-material entrainment. Cross-section surveys and simulated water-surface elevations from a previously run HEC?RAS model were used to calculate the boundary shear stress on the mean streambed, in the thalweg, and on the tops of adjacent alluvial bars for four reference streamflows. Sediment-size characteristics were determined for surficial material on the streambed, on large alluvial bars, and on a streambank. The median particle size (d50) for the streambed samples was 165 millimeters and for the alluvial bars and bank samples was 107 millimeters. Shear stresses generated by the 10-, 50-, and 100-year floods, and by a more common flow that just inundated most of the alluvial bars in the study reach were calculated at 14 of the cross sections used in the Roaring Fork River HEC?RAS model. The Shields equation was used with a Shields parameter of 0.030 to estimate the critical shear stress for entrainment of the median sediment particle size on the mean streambed, in the thalweg, and on adjacent alluvial bar surfaces at the 14 cross sections. Sediment-entrainment

  18. The transformation of nitrogen during pressurized entrained-flow pyrolysis of Chlorella vulgaris.

    Science.gov (United States)

    Maliutina, Kristina; Tahmasebi, Arash; Yu, Jianglong

    2018-08-01

    The transformation of nitrogen in microalgae during entrained-flow pyrolysis of Chlorella vulgaris was systematically investigated at the temperatures of 600-900 °C and pressures of 0.1-4.0 MPa. It was found that pressure had a profound impact on the transformation of nitrogen during pyrolysis. The nitrogen retention in bio-char and its content in bio-oil reached a maximum value at 1.0 MPa. The highest conversion of nitrogen (50.25 wt%) into bio-oil was achieved at 1.0 MPa and 800 °C, which was about 7 wt% higher than that at atmospheric pressure. Higher pressures promoted the formation of pyrrolic-N (N-5) and quaternary-N (N-Q) compounds in bio-oil at the expense of nitrile-N and pyridinic-N (N-6) compounds. The X-Ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results on bio-chars clearly evidenced the transformation of N-5 structures into N-6 and N-Q structures at elevated pressures. The nitrogen transformation pathways during pyrolysis of microalgae were proposed and discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Effects of grid spacer with mixing vane on entrainments and depositions in two-phase annular flows

    Directory of Open Access Journals (Sweden)

    Akimaro Kawahara

    2015-06-01

    Full Text Available The effects of mixing vanes (MVs attached to a grid spacer on the characteristics of air–water annular flows were experimentally investigated. To know the effects, a grid spacer with or without MV was inserted in a vertical circular pipe of 16-mm internal diameter. For three cases (i.e., no spacer, spacer without MV, and spacer with MV, the liquid film thickness, liquid entrainment fraction, and deposition rate were measured by the constant current method, single liquid film extraction method, and double liquid film extraction method, respectively. The MVs significantly promote the re-deposition of liquid droplets in the gas core flow into the liquid film on the channel walls. The deposition mass transfer coefficient is three times higher for the spacer with MV than for the spacer without MV, even for cases 0.3-m downstream from the spacer. The liquid film thickness becomes thicker upstream and downstream for the spacer with MV, compared with the thickness for the spacer without MV and for the case with no spacer.

  20. Development of a custom-made "smart-sphere" to assess incipient entrainment by rolling

    Science.gov (United States)

    Valyrakis, Manousos; Kitsikoudis, Vasileios; Alexakis, Athanasios; Trinder, Jon

    2017-04-01

    The most widely applied criterion for sediment incipient motion in engineering applications is the time- and space-averaged approach of critical Shields shear stress. Nonetheless, in the recent years published research has highlighted the importance of turbulence fluctuations in sediment incipient motion and its stochastic character. The present experimental study investigates statistically the link of the response of a "smart-pebble" to hydrodynamics in near-critical flow conditions and discusses how such a device can be utilized in engineering design. A set of specifically designed fluvial experiments monitoring the entrainment conditions for a "smart-pebble", were carried out in a tilting, recirculating flume in turbulent flow conditions while three-dimensional flow measurements were obtained with an acoustic Doppler velocimeter. The "smart-pebble" employed herein is a custom-made instrumented sphere with 7 cm diameter, which has a number of sensors embedded within its waterproof 3D-printed plastic shell. Specifically, the "smart-pebble" is equipped with miniaturized, off the shelf, low-cost, three-dimensional acceleration, orientation and angular displacement sensors. A 3D-printed local micro topography of known geometry was installed in the flume's test section and the "smart-pebble" was placed there in order to facilitate the analysis. Every time the "smart-sphere" is displaced by the flow a downstream located pin blocks its full entrainment. This allows for continuous recording of the entrainment events due to the passage of energetic events, after which the "smart-pebble" returns to its resting pocket. The "smart-pebble" device under such a configuration allows the recording of normally indiscernible (with the naked eye) vibrations, twitching motions, and full entrainments for the studied particle, allowing its analysis from a Langrangian framework. During the incipient motion experiments the retrieved data are stored in an internal memory unit or

  1. Entrained-flow gasification at elevated pressure: Volume 1: Final technical report, March 1, 1985-April 30,1987

    Energy Technology Data Exchange (ETDEWEB)

    Hedman, P.O.; Smoot, L.D.; Smith, P.J.; Blackham, A.U.

    1987-10-15

    The general purpose of this research program was to develop a basic understanding of the physical and chemical processes in entrained coal gasification and to use the results to improve and evaluate an entrained gasification computer model. The first task included the collection and analysis of in-situ gasifier data at elevated pressures with three coal types (North Dakota lignite, Wyoming subbituminous and Illinois bituminous), the design, construction, and testing of new coal/oxygen/steam injectors with a fourth coal type (Utah bituminous), the collection of supporting turbulent fluid dynamic (LDV) data from cold-flow studies, and the investigation of the feasibility of using laser-based (CARS) daignostic instruments to make measurements in coal flames. The second task included improvements to the two-dimensional gasifier submodels, tabulation and evaluation of new coal devolatilization and char oxidation data for predictions, fundamental studies of turbulent particle dispersion, the development of improved numerical methods, and validation of the comprehensive model through comparison of predictions with experimental results. The third task was to transfer technical advances to industry and to METC through technical seminars, production of a detailed data book, code placement, and publication of results. Research results for these three tasks are summarized briefly here and presented in detail in the body of the report and in supporting references. 202 refs., 73 figs., 23 tabs.

  2. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Santiago Fire, Orange County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Santiago Fire in Orange County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 1.75 inches (44.45 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  3. The Entrainment Rate for Buoyant Plumes in a Crossflow

    Science.gov (United States)

    Devenish, B. J.; Rooney, G. G.; Webster, H. N.; Thomson, D. J.

    2010-03-01

    We consider large-eddy simulations (LES) of buoyant plumes from a circular source with initial buoyancy flux F 0 released into a stratified environment with constant buoyancy frequency N and a uniform crossflow with velocity U. We make a systematic comparison of the LES results with the mathematical theory of plumes in a crossflow. We pay particular attention to the limits {tilde{U}≪1} and {tilde{U}≫ 1}, where {tilde{U}=U/(F_0 N)^{1/4}}, for which analytical results are possible. For {tilde{U}≫ 1}, the LES results show good agreement with the well-known two-thirds law for the rise in height of the plume. Sufficiently far above the source, the centreline vertical velocity of the LES plumes is consistent with the analytical z -1/3 and z -1/2 scalings for respectively {tilde{U}≪ 1} and {tilde{U}≫ 1}. In the general case, where the entrainment is assumed to be the sum of the contributions from the horizontal and vertical velocity components, we find that the discrepancy between the LES data and numerical solutions of the plume equations is largest for {tilde{U}=O(1)}. We propose a modified additive entrainment assumption in which the contributions from the horizontal and vertical velocity components are not equally weighted. We test this against observations of the plume generated by the Buncefield fire in the U.K. in December 2005 and find that the results compare favourably. We also show that the oscillations of the plume as it settles down to its final rise height may be attenuated by the radiation of gravity waves. For {tilde{U}≪ 1} the oscillations decay rapidly due to the transport of energy away from the plume by gravity waves. For {tilde{U}>rsim 1} the gravity waves travel in the same direction and at the same speed as the flow. In this case, the oscillations of the plume do not decay greatly by radiation of gravity waves.

  4. FIRAC - a computer code to predict fire accident effects in nuclear facilities

    International Nuclear Information System (INIS)

    Bolstad, J.W.; Foster, R.D.; Gregory, W.S.

    1983-01-01

    FIRAC is a medium-sized computer code designed to predict fire-induced flows, temperatures, and material transport within the ventilating systems and other airflow pathways in nuclear-related facilities. The code is designed to analyze the behavior of interconnected networks of rooms and typical ventilation system components. This code is one in a family of computer codes that is designed to provide improved methods of safety analysis for the nuclear industry. The structure of this code closely follows that of the previously developed TVENT and EVENT codes. Because a lumped-parameter formulation is used, this code is particularly suitable for calculating the effects of fires in the far field (that is, in regions removed from the fire compartment), where the fire may be represented parametrically. However, a fire compartment model to simulate conditions in the enclosure is included. This model provides transport source terms to the ventilation system that can affect its operation and in turn affect the fire. A basic material transport capability that features the effects of convection, deposition, entrainment, and filtration of material is included. The interrelated effects of filter plugging, heat transfer, gas dynamics, and material transport are taken into account. In this paper the authors summarize the physical models used to describe the gas dynamics, material transport, and heat transfer processes. They also illustrate how a typical facility is modeled using the code

  5. Charge-flow structures as polymeric early-warning fire alarm devices. M.S. Thesis; [metal oxide semiconductors

    Science.gov (United States)

    Sechen, C. M.; Senturia, S. D.

    1977-01-01

    The charge-flow transistor (CFT) and its applications for fire detection and gas sensing were investigated. The utility of various thin film polymers as possible sensing materials was determined. One polymer, PAPA, showed promise as a relative humidity sensor; two others, PFI and PSB, were found to be particularly suitable for fire detection. The behavior of the charge-flow capacitor, which is basically a parallel-plate capacitor with a polymer-filled gap in the metallic tip electrode, was successfully modeled as an RC transmission line. Prototype charge-flow transistors were fabricated and tested. The effective threshold voltage of this metal oxide semiconductor was found to be dependent on whether surface or bulk conduction in the thin film was dominant. Fire tests with a PFI-coated CFT indicate good sensitivity to smouldering fires.

  6. Visual cortex entrains to sign language.

    Science.gov (United States)

    Brookshire, Geoffrey; Lu, Jenny; Nusbaum, Howard C; Goldin-Meadow, Susan; Casasanto, Daniel

    2017-06-13

    Despite immense variability across languages, people can learn to understand any human language, spoken or signed. What neural mechanisms allow people to comprehend language across sensory modalities? When people listen to speech, electrophysiological oscillations in auditory cortex entrain to slow ([Formula: see text]8 Hz) fluctuations in the acoustic envelope. Entrainment to the speech envelope may reflect mechanisms specialized for auditory perception. Alternatively, flexible entrainment may be a general-purpose cortical mechanism that optimizes sensitivity to rhythmic information regardless of modality. Here, we test these proposals by examining cortical coherence to visual information in sign language. First, we develop a metric to quantify visual change over time. We find quasiperiodic fluctuations in sign language, characterized by lower frequencies than fluctuations in speech. Next, we test for entrainment of neural oscillations to visual change in sign language, using electroencephalography (EEG) in fluent speakers of American Sign Language (ASL) as they watch videos in ASL. We find significant cortical entrainment to visual oscillations in sign language sign is strongest over occipital and parietal cortex, in contrast to speech, where coherence is strongest over the auditory cortex. Nonsigners also show coherence to sign language, but entrainment at frontal sites is reduced relative to fluent signers. These results demonstrate that flexible cortical entrainment to language does not depend on neural processes that are specific to auditory speech perception. Low-frequency oscillatory entrainment may reflect a general cortical mechanism that maximizes sensitivity to informational peaks in time-varying signals.

  7. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Witch Fire, San Diego County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Witch Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  8. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Buckweed Fire, Los Angeles County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Buckweed Fire in Los Angeles County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  9. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Canyon Fire, Los Angeles County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Canyon Fire in Los Angeles County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  10. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Poomacha Fire, San Diego County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Poomacha Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  11. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Rice Fire, San Diego County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Rice Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 1.75 inches (44.45 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  12. Emergency assessment of debris-flow hazards from basins burned by the 2007 Harris Fire, San Diego County, southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    IntroductionThe objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Harris Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 1.75 inches (44.45 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  13. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Ammo Fire, San Diego County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Ammo Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 1.75 inches (44.45 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  14. Fire simulation in nuclear facilities: the FIRAC code and supporting experiments

    International Nuclear Information System (INIS)

    Burkett, M.W.; Martin, R.A.; Fenton, D.L.; Gunaji, M.V.

    1984-01-01

    The fire accident analysis computer code FIRAC was designed to estimate radioactive and nonradioactive source terms and predict fire-induced flows and thermal and material transport within the ventilation systems of nuclear fuel cycle facilities. FIRAC maintains its basic structure and features and has been expanded and modified to include the capabilities of the zone-type compartment fire model computer code FIRIN developed by Battelle Pacific Northwest Laboratory. The two codes have been coupled to provide an improved simulation of a fire-induced transient within a facility. The basic material transport capability of FIRAC has been retained and includes estimates of entrainment, convection, deposition, and filtration of material. The interrelated effects of filter plugging, heat transfer, gas dynamics, material transport, and fire and radioactive source terms also can be simulated. Also, a sample calculation has been performed to illustrate some of the capabilities of the code and how a typical facility is modeled with FIRAC. In addition to the analytical work being performed at Los Alamos, experiments are being conducted at the New Mexico State University to support the FIRAC computer code development and verification. This paper summarizes two areas of the experimental work that support the material transport capabiities of the code: the plugging of high-efficiency particulate air (HEPA) filters by combustion aerosols and the transport and deposition of smoke in ventilation system ductwork

  15. Fire simulation in nuclear facilities--the FIRAC code and supporting experiments

    International Nuclear Information System (INIS)

    Burkett, M.W.; Martin, R.A.; Fenton, D.L.; Gunaji, M.V.

    1985-01-01

    The fire accident analysis computer code FIRAC was designed to estimate radioactive and nonradioactive source terms and predict fire-induced flows and thermal and material transport within the ventilation systems of nuclear fuel cycle facilities. FIRAC maintains its basic structure and features and has been expanded and modified to include the capabilities of the zone-type compartment fire model computer code FIRIN developed by Battelle Pacific Northwest Laboratory. The two codes have been coupled to provide an improved simulation of a fire-induced transient within a facility. The basic material transport capability of FIRAC has been retained and includes estimates of entrainment, convection, deposition, and filtration of material. The interrelated effects of filter plugging, heat transfer, gas dynamics, material transport, and fire and radioactive source terms also can be simulated. Also, a sample calculation has been performed to illustrate some of the capabilities of the code and how a typical facility is modeled with FIRAC. In addition to the analytical work being performed at Los Alamos, experiments are being conducted at the New Mexico State University to support the FIRAC computer code development and verification. This paper summarizes two areas of the experimental work that support the material transport capabilities of the code: the plugging of high-efficiency particulate air (HEPA) filters by combustion aerosols and the transport and deposition of smoke in ventilation system ductwork

  16. Morphodynamic Modeling of the Lower Yellow River, China: Flux (Equilibrium) Form or Entrainment (Nonequilibrium) Form of Sediment Mass Conservation?

    Science.gov (United States)

    An, C.; Parker, G.; Ma, H.; Naito, K.; Moodie, A. J.; Fu, X.

    2017-12-01

    Models of river morphodynamics consist of three elements: (1) a treatment of flow hydraulics, (2) a formulation relating some aspect of sediment transport to flow hydraulics, and (3) a description of sediment conservation. In the case of unidirectional river flow, the Exner equation of sediment conservation is commonly described in terms of a flux-based formulation, in which bed elevation variation is related to the streamwise gradient of sediment transport rate. An alternate formulation of the Exner equation, however, is the entrainment-based formulation in which bed elevation variation is related to the difference between the entrainment rate of bed sediment into suspension and the deposition rate of suspended sediment onto the bed. In the flux-based formulation, sediment transport is regarded to be in a local equilibrium state (i.e., sediment transport rate locally equals sediment transport capacity). However, the entrainment-based formulation does not require this constraint; the sediment transport rate may lag in space and time behind the changing flow conditions. In modeling the fine-grained Lower Yellow River, it is usual to treat sediment conservation in terms of an entrainment-based (nonequilibrium) rather than a flux-based (equilibrium) formulation with the consideration that fine-grained sediment may be entrained at one place but deposited only at some distant location downstream. However, the differences in prediction between the two formulations are still not well known, and the entrainment formulation may not always be necessary for the Lower Yellow River. Here we study this problem by comparing the results of flux-based and entrainment-based morphodynamics under conditions typical of the Yellow River, using sediment transport equations specifically designed for the Lower Yellow River. We find, somewhat unexpectedly, that in a treatment of a 200-km reach using uniform sediment, there is little difference between the two formulations unless the

  17. Dissociable effects of dopamine on neuronal firing rate and synchrony in the dorsal striatum

    Directory of Open Access Journals (Sweden)

    John M Burkhardt

    2009-10-01

    Full Text Available Previous studies showed that dopamine depletion leads to both changes in firing rate and in neuronal synchrony in the basal ganglia. Since dopamine D1 and D2 receptors are preferentially expressed in striatonigral and striatopallidal medium spiny neurons, respectively, we investigated the relative contribution of lack of D1 and/or D2-type receptor activation to the changes in striatal firing rate and synchrony observed after dopamine depletion. Similar to what was observed after dopamine depletion, co-administration of D1 and D2 antagonists to mice chronically implanted with multielectrode arrays in the striatum caused significant changes in firing rate, power of the local field potential (LFP oscillations, and synchrony measured by the entrainment of neurons to striatal local field potentials. However, although blockade of either D1 or D2 type receptors produced similarly severe akinesia, the effects on neural activity differed. Blockade of D2 receptors affected the firing rate of medium spiny neurons and the power of the LFP oscillations substantially, but it did not affect synchrony to the same extent. In contrast, D1 blockade affected synchrony dramatically, but had less substantial effects on firing rate and LFP power. Furthermore, there was no consistent relation between neurons changing firing rate and changing LFP entrainment after dopamine blockade. Our results suggest that the changes in rate and entrainment to the LFP observed in medium spiny neurons after dopamine depletion are somewhat dissociable, and that lack of D1- or D2-type receptor activation can exert independent yet interactive pathological effects during the progression of Parkinson’s disease.

  18. A FIRE-ACE/SHEBA Case Study of Mixed-Phase Arctic Boundary Layer Clouds: Entrainment Rate Limitations on Rapid Primary Ice Nucleation Processes

    Science.gov (United States)

    Fridlin, Ann; vanDiedenhoven, Bastiaan; Ackerman, Andrew S.; Avramov, Alexander; Mrowiec, Agnieszka; Morrison, Hugh; Zuidema, Paquita; Shupe, Matthew D.

    2012-01-01

    Observations of long-lived mixed-phase Arctic boundary layer clouds on 7 May 1998 during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE)Arctic Cloud Experiment (ACE)Surface Heat Budget of the Arctic Ocean (SHEBA) campaign provide a unique opportunity to test understanding of cloud ice formation. Under the microphysically simple conditions observed (apparently negligible ice aggregation, sublimation, and multiplication), the only expected source of new ice crystals is activation of heterogeneous ice nuclei (IN) and the only sink is sedimentation. Large-eddy simulations with size-resolved microphysics are initialized with IN number concentration N(sub IN) measured above cloud top, but details of IN activation behavior are unknown. If activated rapidly (in deposition, condensation, or immersion modes), as commonly assumed, IN are depleted from the well-mixed boundary layer within minutes. Quasi-equilibrium ice number concentration N(sub i) is then limited to a small fraction of overlying N(sub IN) that is determined by the cloud-top entrainment rate w(sub e) divided by the number-weighted ice fall speed at the surface v(sub f). Because w(sub c) 10 cm/s, N(sub i)/N(sub IN)<< 1. Such conditions may be common for this cloud type, which has implications for modeling IN diagnostically, interpreting measurements, and quantifying sensitivity to increasing N(sub IN) (when w(sub e)/v(sub f)< 1, entrainment rate limitations serve to buffer cloud system response). To reproduce observed ice crystal size distributions and cloud radar reflectivities with rapidly consumed IN in this case, the measured above-cloud N(sub IN) must be multiplied by approximately 30. However, results are sensitive to assumed ice crystal properties not constrained by measurements. In addition, simulations do not reproduce the pronounced mesoscale heterogeneity in radar reflectivity that is observed.

  19. Entrainment Zone Characteristics and Entrainment Rates in Cloud-Topped Boundary Layers from DYCOMS-II

    Science.gov (United States)

    2012-03-01

    Malinowski , J. L. Brenguier, and F. Burnet, 2005: Holes and entrainment in stratocumulus. J. Atmos. Sci., 62, 443–459. Glickman, T. S...of the Entrainment Zone in Cloud-topped Boundary Layers. Department of Meteorology, NPS, 93 pp. Krzysztof, Haman E., S. P. Malinowski , M. J

  20. In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions

    Science.gov (United States)

    Kean, J.W.; Staley, D.M.; Cannon, S.H.

    2011-01-01

    Debris flows often occur in burned steeplands of southern California, sometimes causing property damage and loss of life. In an effort to better understand the hydrologic controls on post-fire debris-flow initiation, timing and magnitude, we measured the flow stage, rainfall, channel bed pore fluid pressure and hillslope soil-moisture accompanying 24 debris flows recorded in five different watersheds burned in the 2009 Station and Jesusita Fires (San Gabriel and Santa Ynez Mountains). The measurements show substantial differences in debris-flow dynamics between sites and between sequential events at the same site. Despite these differences, the timing and magnitude of all events were consistently associated with local peaks in short duration (landslides. By identifying the storm characteristics most closely associated with post-fire debris flows, these measurements provide valuable guidance for warning operations and important constraints for developing and testing models of post-fire debris flows. copyright. 2011 by the American Geophysical Union.

  1. Suspended sediment entrainment estimation in unsteady turbulent flows by means of a stochastic meted; Computo de la incorporacion de sedimento en suspension en flujos turbulentos no permanentes utilizando un enfoque estocastico

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Jose Fernando; Garcia, Marcelo Horacio [Universidad de Illinois (United States); Admiraal, David Mark [Universidad de Nebraska en Lincoln (United States)

    2001-06-01

    In order to compute the total amount and vertical distribution of suspended sediment, a reference concentration near the bed or entrainment function is needed, and considerable research effort has been dedicated to obtain such formulae. Several entrainment functions are available in the literature, but all of them have been developed for steady, uniform flow conditions. The ability of such relationships to predict entrainment rates in unsteady flows has not been demonstrated, nor has there been any attempt to develop a general formulation that work for both steady and unsteady flow conditions. The traditional approach relates the entrainment of sediment to the wall shear stress associated with skin friction in a deterministic way, providing only a relation between mean values. An alternative is to consider both the shear stress and the entrainment as stochastic turbulent quantities and to express them in terms of their probability density functions (PDFs). In this way, statistics of the entrainment can be obtained from measured shear stress PDFs, either in steady or unsteady situations, since the effect of unsteadiness is embedded in the PDF. This new methodology was used to estimate sediment entrainment produced by the passage of vessels in the Mississippi River and the Illinois River. Using a low order cumulant expansion to describe the PDF of the shear stress and a generalized version of Garcia and Parker's entrainment relationship, an expression for the average of the entrainment as a function of the average, variance, skewness of the shear stress distribution was obtained. Predictions compared favourably with values reported in the literature. [Spanish] Para calcular la cantidad total y distribucion vertical de sedimento en suspension es preciso conocer una concentracion de referencia cerca del lecho o funcion de incorporacion, para lo cual se ha hecho un considerable esfuerzo por obtener dichas formulas. Existen varias funciones de incorporacion en la

  2. Entrainment to periodic initiation and transition rates in a computational model for gene translation.

    Directory of Open Access Journals (Sweden)

    Michael Margaliot

    Full Text Available Periodic oscillations play an important role in many biomedical systems. Proper functioning of biological systems that respond to periodic signals requires the ability to synchronize with the periodic excitation. For example, the sleep/wake cycle is a manifestation of an internal timing system that synchronizes to the solar day. In the terminology of systems theory, the biological system must entrain or phase-lock to the periodic excitation. Entrainment is also important in synthetic biology. For example, connecting several artificial biological systems that entrain to a common clock may lead to a well-functioning modular system. The cell-cycle is a periodic program that regulates DNA synthesis and cell division. Recent biological studies suggest that cell-cycle related genes entrain to this periodic program at the gene translation level, leading to periodically-varying protein levels of these genes. The ribosome flow model (RFM is a deterministic model obtained via a mean-field approximation of a stochastic model from statistical physics that has been used to model numerous processes including ribosome flow along the mRNA. Here we analyze the RFM under the assumption that the initiation and/or transition rates vary periodically with a common period T. We show that the ribosome distribution profile in the RFM entrains to this periodic excitation. In particular, the protein synthesis pattern converges to a unique periodic solution with period T. To the best of our knowledge, this is the first proof of entrainment in a mathematical model for translation that encapsulates aspects such as initiation and termination rates, ribosomal movement and interactions, and non-homogeneous elongation speeds along the mRNA. Our results support the conjecture that periodic oscillations in tRNA levels and other factors related to the translation process can induce periodic oscillations in protein levels, and may suggest a new approach for re-engineering genetic

  3. Study of air entrainment in high pressure spray: optics diagnostics and application to the Diesel injection; Etude de l'entrainement d'air dans un spray haute pression: diagnostics optiques et application a l'injection diesel

    Energy Technology Data Exchange (ETDEWEB)

    Arbeau, A.

    2004-12-15

    The actual development of the engine must reply to a will of fuel consumption reduction and to norms more and more strict concerning the pollutant emissions. Although the Diesel engines are efficient, the NO{sub x} and particle emissions mainly come from the existence of wealthy fuel zone preventing an optimal combustion. Therefore, the air / fuel mixing preparation, highly controlled by the air entrainment in spray, is essential. In this context, we have developed metrological tools in order to analyse the air entrainment mechanism in a dense spray. The Particle Image Velocimetry (PIV) technique is first applied to a conical spray with an injection pressure less than 100 bars to study the air entrainment in spray. A transfer of the methodologies allows then the characterisation and the understanding of the air entrainment mechanism in high pressure full spray (injection pressure less than 1600 bars) type Diesel one. The influence of injection parameters (injection pressure and back pressure) on the mixing rate is studied. The increase of the injection pressure from 800 to 1600 bars implies an increase of the mixing rate of 60 %. Moreover, the thermodynamic conditions of the ambient air, simulated by the chamber back pressure, widely favours the mixing rate. Actually, this latter increases of 350 % when the chamber back pressure varies from 1 to 7 bars. The experimental results do not follow classical laws of air entrainment in one-phase flow jet with variable density, but are in good agreement with an integral model for air entrainment in an axisymmetric full spray. Finally, the Fluorescence Particle Image Velocimetry (FPIV) is introduced in order to extend the PIV application field in dense two-phase flows. (author)

  4. Experimental investigations on a common centrifugal pump operating under gas entrainment conditions

    Energy Technology Data Exchange (ETDEWEB)

    Schäfer, Thomas, E-mail: thomas.schaefer@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics (Germany); Neumann, Martin [Technische Universität Dresden, AREVA Endowed Chair of Imaging Techniques in Energy and Process Engineering (Germany); Bieberle, André [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics (Germany); Hampel, Uwe [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics (Germany); Technische Universität Dresden, AREVA Endowed Chair of Imaging Techniques in Energy and Process Engineering (Germany)

    2017-05-15

    Highlights: • The pump performance has been evaluated for several gas entrainment conditions. • The gas entraining flow regime has a large impact on the pump performance. • High-resolution gamma-ray computed tomography (HireCT) has been applied. • Gas holdup inside the operating impeller has been visualized and quantified. • Gas holdup profiles along selected streamlines have been calculated. - Abstract: This paper presents an experimental study on the effects of additional gas entrainment in centrifugal pumps designed for conveying liquid phases only. The pump performance has been evaluated for several gas entrainment conditions, and for various operational settings of the pump, such as its alignment and the rotational speed of the impeller. As a main performance indicator the impact of entrained gas on the hydraulic power of the pump has been analyzed using experimental data. Additionally, high-resolution gamma-ray computed tomography (HireCT) operated in time-averaged rotation-synchronized scanning mode has been applied to quantify local phase fraction distributions inside the rapidly rotating pump impeller. Based on these quantitative tomographic measurements, gas holdup profiles along selected streamlines have been calculated and gas accumulation areas inside the impeller chambers have been visualized. Thus, various internally accumulated gas holdup patterns have been identified and, eventually, associated with characteristic pump performance behaviors. Moreover, the tomographic measuring method allowed an enhanced gas holdup analysis in specified pump compartments. As a result, the related specific gas and liquid phase holdup profiles have been evaluated.

  5. Experimental investigations on a common centrifugal pump operating under gas entrainment conditions

    International Nuclear Information System (INIS)

    Schäfer, Thomas; Neumann, Martin; Bieberle, André; Hampel, Uwe

    2017-01-01

    Highlights: • The pump performance has been evaluated for several gas entrainment conditions. • The gas entraining flow regime has a large impact on the pump performance. • High-resolution gamma-ray computed tomography (HireCT) has been applied. • Gas holdup inside the operating impeller has been visualized and quantified. • Gas holdup profiles along selected streamlines have been calculated. - Abstract: This paper presents an experimental study on the effects of additional gas entrainment in centrifugal pumps designed for conveying liquid phases only. The pump performance has been evaluated for several gas entrainment conditions, and for various operational settings of the pump, such as its alignment and the rotational speed of the impeller. As a main performance indicator the impact of entrained gas on the hydraulic power of the pump has been analyzed using experimental data. Additionally, high-resolution gamma-ray computed tomography (HireCT) operated in time-averaged rotation-synchronized scanning mode has been applied to quantify local phase fraction distributions inside the rapidly rotating pump impeller. Based on these quantitative tomographic measurements, gas holdup profiles along selected streamlines have been calculated and gas accumulation areas inside the impeller chambers have been visualized. Thus, various internally accumulated gas holdup patterns have been identified and, eventually, associated with characteristic pump performance behaviors. Moreover, the tomographic measuring method allowed an enhanced gas holdup analysis in specified pump compartments. As a result, the related specific gas and liquid phase holdup profiles have been evaluated.

  6. Formation and entrainment of fluid mud layers in troughs of subtidal dunes in an estuarine turbidity zone

    DEFF Research Database (Denmark)

    Becker, Marius; Schrottke, Kerstin; Bartholomä, Alexander

    2013-01-01

    25 g/L below the lutocline to 70 g/L at the river bed, whereas the gelling concentration was below 70 g/L. Sites of fluid mud formation coincided with the location of the estuarine turbidity zone during slack water. On average, near-bed density gradients were initially observed in dune troughs 1.2 h...... before slack water, and all fluid mud layers were entrained 2.3 h after slack water. No shear instabilities occurred until 1.8 h after slack water. While the flow was oriented in the dune direction, rapid entrainment was related to the development of the turbulent flow field behind dunes and is explained...... to be induced by advection of strong turbulence during accelerating currents. Fluid mud layers in dune troughs were entrained at an earlier point in time after slack water, compared to adjacent layers formed on a comparatively flat bed, where dune crests did not protrude from the lutocline....

  7. A comparative efficacy study of photic driving brainwave entrainment technology with a novel form of more direct entrainment

    Science.gov (United States)

    Knowles, Richard Thomas

    This exploratory study compared the efficacy of a novel brainwave electromagnetic (EM) entrainment technology against a more conventional technology utilizing the photic-driving technique. Both experimental conditions were also compared with a 7-minute control session that took place immediately before each stimulation session. The Schumann Resonance (SR) frequency was selected as the delivery signal and was chosen because of previous findings suggesting that entrainment to this frequency can often produce transpersonal if not paranormal, experiences in the entrainee, which sometimes resemble remote viewing or out-of-body experiences. A pilot study determined which of two novel entrainment modalities (a copper coil or a 16-solenoid headset) worked most effectively for use with the rest of the study. In the main study, an artificial SR signal at 7.8Hz was delivered during the photic-driving sessions, but a recording of the real-time SR was used to deliver the entrainment signal during sessions devoted to the electromagnetic entrainment modality. Sixteen participants were recruited from the local area, and EEG recordings were acquired via a 32-channel Deymed electroencephalography system. Comparative analyses were performed between the control and experimental portions of each session to assess for efficacy of the novel entrainment modality used, and, in the main study, between the electromagnetic and photic-driving sessions, to assess for differential entrainment efficacy between these groups. A follow-up study was additionally performed primarily to determine whether responders could replicate their entrainment effect from the main study. Results showed that EM entrainment appeared to be possible but is not nearly as robust or reliable as photic driving. Additionally, no profound transpersonal or paranormal experiences were elicited during the course of the study, and, when asked, participants were not able to determine with any degree of success, when the

  8. Entrainment, transport and deposition of sediment by saline gravity currents

    Science.gov (United States)

    Zordan, Jessica; Juez, Carmelo; Schleiss, Anton J.; Franca, Mário J.

    2018-05-01

    Few studies have addressed simultaneously the feedback between the hydrodynamics of a gravity current and the geomorphological changes of a mobile bed. Hydrodynamic quantities such as turbulent and mean velocities, bed shear stress and turbulent stresses undoubtedly govern the processes of entrainment, transport and deposition. On the other hand, the incorporation of entrained sediment in the current may change its momentum by introducing extra internal stresses, introducing thus a feedback process. These two main questions are here investigated. Laboratory experiments of saline gravity currents, produced by lock-exchange, flowing over a mobile bed channel reach, are here reported. Different initial buoyancies of the current in the lock are tested together with three different grain sizes of the non-coherent sediment that form the erodible bed. Results from velocity measurements are combined with the visualization of the sediment movement in the mobile reach and with post-test topographic and photo surveys of the geomorphology modifications of the channel bed. Mean and turbulent velocities are measured and bed shear stress and Reynolds stresses are estimated. We show that the mean vertical component of the velocity and bed shear stress are highly correlated with the first instants of sediment entrainment. Vertical turbulent velocity is similarly related to entrainment, although with lower correlation values, contributing as well to the sediment movement. Bed shear stress and Reynolds shear stress measured near the bed are correlated with sediment entrainment for longer periods, indicating that these quantities are associated to distal transport as well. Geomorphological changes in the mobile bed are strongly related to the impulse caused by the bed shear stress on the sediment. On the other hand, we show that the nature of the grain of the mobile bed reach influences the hydrodynamics of the current which means that a feedback mechanisms between both occurs during

  9. Aerosol entrainment from a sparged non-Newtonian slurry.

    Science.gov (United States)

    Fritz, Brad G

    2006-08-01

    Previous bench-scale experiments have provided data necessary for the development of empirical models that describe aerosol entrainment from bubble bursting. However, previous work has not been extended to non-Newtonian liquid slurries. Design of a waste treatment plant on the Hanford Site in Washington required an evaluation of the applicability of these models outside of their intended range. For this evaluation, aerosol measurements were conducted above an air-sparged mixing tank filled with simulated waste slurry possessing Bingham plastic rheological properties. Three aerosol-size fractions were measured at three sampling heights and for three different sparging rates. The measured entrainment was compared with entrainment models. One model developed based on bench-scale air-water experiments agreed well with measured entrainment. Another model did not agree well with the measured entrainment. It appeared that the source of discrepancy between measured and modeled entrainment stemmed from application beyond the range of data used to develop the model. A possible separation in entrainment coefficients between air-water and steam-water systems was identified. A third entrainment model was adapted to match experimental conditions and fit a posteri to the experimental data, resulting in a modified version that resulted in estimated entrainment rates similar to the first model.

  10. Model-based Fuel Flow Control for Fossil-fired Power Plants

    DEFF Research Database (Denmark)

    Niemczyk, Piotr

    2010-01-01

    -fired power plants represent the largest reserve of such controllable power sources in several countries. However, their production take-up rates are limited, mainly due to poor fuel flow control. The thesis presents analysis of difficulties and potential improvements in the control of the coal grinding...

  11. Exploring Entrainment Patterns of Human Emotion in Social Media.

    Science.gov (United States)

    He, Saike; Zheng, Xiaolong; Zeng, Daniel; Luo, Chuan; Zhang, Zhu

    2016-01-01

    Emotion entrainment, which is generally defined as the synchronous convergence of human emotions, performs many important social functions. However, what the specific mechanisms of emotion entrainment are beyond in-person interactions, and how human emotions evolve under different entrainment patterns in large-scale social communities, are still unknown. In this paper, we aim to examine the massive emotion entrainment patterns and understand the underlying mechanisms in the context of social media. As modeling emotion dynamics on a large scale is often challenging, we elaborate a pragmatic framework to characterize and quantify the entrainment phenomenon. By applying this framework on the datasets from two large-scale social media platforms, we find that the emotions of online users entrain through social networks. We further uncover that online users often form their relations via dual entrainment, while maintain it through single entrainment. Remarkably, the emotions of online users are more convergent in nonreciprocal entrainment. Building on these findings, we develop an entrainment augmented model for emotion prediction. Experimental results suggest that entrainment patterns inform emotion proximity in dyads, and encoding their associations promotes emotion prediction. This work can further help us to understand the underlying dynamic process of large-scale online interactions and make more reasonable decisions regarding emergency situations, epidemic diseases, and political campaigns in cyberspace.

  12. Physical and Numerical Investigations of Mould Flux Entrainment into Liquid Steel

    Directory of Open Access Journals (Sweden)

    Jowsa J.

    2016-12-01

    Full Text Available This paper presents results of model tests, performed in order to analyze phenomenon of slag droplets entrainment into steel in mould, during continuous casting process. The carried out studies took the form of laboratory experiments using physical model, in which – using similarity criteria – the behaviour of interfacial boundary liquid steel-liquid slag has been simulated using water and silicon oils, differing in physicochemical properties. Additionally, based on PIV (Particle Image Velocimetry measurements and numerical simulations, vector flow field and values of critical velocities, at which observed the occurrence of interfacial boundary silicon oil-water instability have been identified. Based on the carried out investigations, results, that illustrate relationship between critical entrainment velocity and physicochemical properties of oils have been presented.

  13. Experimental investigation on an entrained flow type biomass gasification system using coconut coir dust as powdery biomass feedstock.

    Science.gov (United States)

    Senapati, P K; Behera, S

    2012-08-01

    Based on an entrained flow concept, a prototype atmospheric gasification system has been designed and developed in the laboratory for gasification of powdery biomass feedstock such as rice husks, coconut coir dust, saw dust etc. The reactor was developed by adopting L/D (height to diameter) ratio of 10, residence time of about 2s and a turn down ratio (TDR) of 1.5. The experimental investigation was carried out using coconut coir dust as biomass feedstock with a mean operating feed rate of 40 kg/h The effects of equivalence ratio in the range of 0.21-0.3, steam feed at a fixed flow rate of 12 kg/h, preheat on reactor temperature, product gas yield and tar content were investigated. The gasifier could able to attain high temperatures in the range of 976-1100 °C with gas lower heating value (LHV) and peak cold gas efficiency (CGE) of 7.86 MJ/Nm3 and 87.6% respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Effects of pressure on morphology and structure of bio-char from pressurized entrained-flow pyrolysis of microalgae

    Directory of Open Access Journals (Sweden)

    Kristina Maliutina

    2018-06-01

    Full Text Available The present dataset describes the entrained-flow pyrolysis of Microalgae Chlorella vulgaris and the results obtained during bio-char characterization. The dataset includes a brief explanation of the experimental procedure, experimental conditions and the influence of pyrolysis conditions on bio-chars morphology and carbon structure. The data show an increase in sphericity and surface smoothness of bio-chars at higher pressures and temperatures. Data confirmed that the swelling ratio of bio-chars increased with pressure up to 2.0 MPa. Consequently, changes in carbon structure of bio-chars were investigated using Raman spectroscopy. The data showed the increase in carbon order of chars at elevated pressures. Changes in the chemical structure of bio-char as a function of pyrolysis conditions were investigated using FTIR analysis. Keywords: Microalgae, Bio-char, Particle swelling, Pressurized pyrolysis

  15. Modeling char conversion under suspension fired conditions in O2/N2 and O2/CO2 atmospheres

    DEFF Research Database (Denmark)

    Brix, Jacob; Jensen, Peter Arendt; Jensen, Anker Degn

    2011-01-01

    The aim of this investigation has been to model combustion under suspension fired conditions in O2/N2 and O2/CO2 mixtures. Experiments used for model validation have been carried out in an electrically heated Entrained Flow Reactor (EFR) at temperatures between 1173 K and 1673 K with inlet O2...... concentrations between 5 and 28 vol.%. The COal COmbustion MOdel, COCOMO, includes the three char morphologies: cenospheric char, network char and dense char each divided between six discrete particle sizes. Both combustion and gasification with CO2 are accounted for and reaction rates include thermal char...

  16. Exploring Entrainment Patterns of Human Emotion in Social Media

    Science.gov (United States)

    Luo, Chuan; Zhang, Zhu

    2016-01-01

    Emotion entrainment, which is generally defined as the synchronous convergence of human emotions, performs many important social functions. However, what the specific mechanisms of emotion entrainment are beyond in-person interactions, and how human emotions evolve under different entrainment patterns in large-scale social communities, are still unknown. In this paper, we aim to examine the massive emotion entrainment patterns and understand the underlying mechanisms in the context of social media. As modeling emotion dynamics on a large scale is often challenging, we elaborate a pragmatic framework to characterize and quantify the entrainment phenomenon. By applying this framework on the datasets from two large-scale social media platforms, we find that the emotions of online users entrain through social networks. We further uncover that online users often form their relations via dual entrainment, while maintain it through single entrainment. Remarkably, the emotions of online users are more convergent in nonreciprocal entrainment. Building on these findings, we develop an entrainment augmented model for emotion prediction. Experimental results suggest that entrainment patterns inform emotion proximity in dyads, and encoding their associations promotes emotion prediction. This work can further help us to understand the underlying dynamic process of large-scale online interactions and make more reasonable decisions regarding emergency situations, epidemic diseases, and political campaigns in cyberspace. PMID:26953692

  17. Exploring Entrainment Patterns of Human Emotion in Social Media.

    Directory of Open Access Journals (Sweden)

    Saike He

    Full Text Available Emotion entrainment, which is generally defined as the synchronous convergence of human emotions, performs many important social functions. However, what the specific mechanisms of emotion entrainment are beyond in-person interactions, and how human emotions evolve under different entrainment patterns in large-scale social communities, are still unknown. In this paper, we aim to examine the massive emotion entrainment patterns and understand the underlying mechanisms in the context of social media. As modeling emotion dynamics on a large scale is often challenging, we elaborate a pragmatic framework to characterize and quantify the entrainment phenomenon. By applying this framework on the datasets from two large-scale social media platforms, we find that the emotions of online users entrain through social networks. We further uncover that online users often form their relations via dual entrainment, while maintain it through single entrainment. Remarkably, the emotions of online users are more convergent in nonreciprocal entrainment. Building on these findings, we develop an entrainment augmented model for emotion prediction. Experimental results suggest that entrainment patterns inform emotion proximity in dyads, and encoding their associations promotes emotion prediction. This work can further help us to understand the underlying dynamic process of large-scale online interactions and make more reasonable decisions regarding emergency situations, epidemic diseases, and political campaigns in cyberspace.

  18. Cloud-Top Entrainment in Stratocumulus Clouds

    Science.gov (United States)

    Mellado, Juan Pedro

    2017-01-01

    Cloud entrainment, the mixing between cloudy and clear air at the boundary of clouds, constitutes one paradigm for the relevance of small scales in the Earth system: By regulating cloud lifetimes, meter- and submeter-scale processes at cloud boundaries can influence planetary-scale properties. Understanding cloud entrainment is difficult given the complexity and diversity of the associated phenomena, which include turbulence entrainment within a stratified medium, convective instabilities driven by radiative and evaporative cooling, shear instabilities, and cloud microphysics. Obtaining accurate data at the required small scales is also challenging, for both simulations and measurements. During the past few decades, however, high-resolution simulations and measurements have greatly advanced our understanding of the main mechanisms controlling cloud entrainment. This article reviews some of these advances, focusing on stratocumulus clouds, and indicates remaining challenges.

  19. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Ranch Fire, Ventura and Los Angeles Counties, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Ranch Fire in Ventura and Los Angeles Counties, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  20. Visuomotor Entrainment and the Frequency-Dependent Response of Walking Balance to Perturbations.

    Science.gov (United States)

    Franz, Jason R; Francis, Carrie; Allen, Matt; Thelen, Darryl G

    2016-08-26

    Visuomotor entrainment, or the synchronization of motor responses to visual stimuli, is a naturally emergent phenomenon in human standing. Our purpose was to investigate the prevalence and resolution of visuomotor entrainment in walking and the frequency-dependent response of walking balance to perturbations. We used a virtual reality environment to manipulate optical flow in ten healthy young adults during treadmill walking. A motion capture system recorded trunk, sacrum, and heel marker trajectories during a series of 3-min conditions in which we perturbed a virtual hallway mediolaterally with systematic changes in the driving frequencies of perceived motion. We quantified visuomotor entrainment using spectral analyses and balance deficits using trunk sway, gait variability, and detrended fluctuation analyses (DFA). ML kinematics were highly sensitive to visual perturbations, and instinctively synchronized (i.e., entrained) to a broad range of driving frequencies of perceived ML motion. However, the influence of visual perturbations on metrics of walking balance was frequency-dependent and governed by their proximity to stride frequency. Specifically, we found that a driving frequency nearest to subjects' average stride frequency uniquely compromised trunk sway, gait variability, and step-to-step correlations. We conclude that visuomotor entrainment is a robust and naturally emerging phenomenon during human walking, involving coordinated and frequency-dependent adjustments in trunk sway and foot placement to maintain balance at the whole-body level. These findings provide mechanistic insight into how the visuomotor control of walking balance is disrupted by visual perturbations and important reference values for the emergence of balance deficits due to age, injury, or disease.

  1. NUMERICAL ANALYSIS OF INFLUENCE OF EXOGENOUS FIRE IN DOG HEADING ON PARAMETERS OF THE AIR STREAM FLOWING THROUGH THIS HEADING

    Directory of Open Access Journals (Sweden)

    Magdalena TUTAK

    2014-04-01

    Full Text Available Flow of ventilation air stream through the dog heading with a fire centre is the flow with complex character, during which as a result of emission of fire gases into the mining atmosphere, there occur to disturbances of its flow. In the paper there is presented a numerical analysis of an influence of exogenous fire in a dog heading, on the parameters of the ventilation air stream flowing through this heading. Modeling tests were carried out with a use of ANSYS software, basing on the Finite Volume Method. For the made assumptions, there were determined physical parameters of air stream flowing through the heading with a fire centre, and also changes in mass fraction of gases in this stream during its flow through the analyzed heading: oxygen, carbon monoxide and carbon dioxide. As a result of performed analysis over the fire centre, the local increase of velocity and temperature and violent decrease of static pressure were recorded. Model of heading presented in the paper gives possibilities for development, and then the analysis of more complicated problems in a range of ventilation of mining headings.

  2. Entrainment: an annotated bibliography. Interim report

    International Nuclear Information System (INIS)

    Carrier, R.F.; Hannon, E.H.

    1979-04-01

    The 604 annotated references in this bibliography on the effects of pumped entrainment of aquatic organisms through the cooling systems of thermal power plants were compiled from published and unpublished literature and cover the years 1947 through 1977. References to published literature were obtained by searching large-scale commercial data bases, ORNL in-house-generated data bases, relevant journals, and periodical bibliographies. The unpublished literature is a compilation of Sections 316(a) and 316(b) demonstrations, environmental impact statements, and environmental reports prepared by the utilities in compliance with Federal Water Pollution Control Administration regulations. The bibliography includes references on monitoring studies at power plant sites, laboratory studies of physical and biological effects on entrained organisms, engineering strategies for the mitigation of entrainment effects, and selected theoretical studies concerned with the methodology for determining entrainment effects

  3. Temperature compensation and entrainment in circadian rhythms

    International Nuclear Information System (INIS)

    Bodenstein, C; Heiland, I; Schuster, S

    2012-01-01

    To anticipate daily variations in the environment and coordinate biological activities into a daily cycle many organisms possess a circadian clock. In the absence of external time cues the circadian rhythm persists with a period of approximately 24 h. The clock phase can be shifted by single pulses of light, darkness, chemicals, or temperature and this allows entrainment of the clock to exactly 24 h by cycles of these zeitgebers. On the other hand, the period of the circadian rhythm is kept relatively constant within a physiological range of constant temperatures, which means that the oscillator is temperature compensated. The mechanisms behind temperature compensation and temperature entrainment are not fully understood, neither biochemically nor mathematically. Here, we theoretically investigate the interplay of temperature compensation and entrainment in general oscillatory systems. We first give an analytical treatment for small temperature shifts and derive that every temperature-compensated oscillator is entrainable to external small-amplitude temperature cycles. Temperature compensation ensures that this entrainment region is always centered at the endogenous period regardless of possible seasonal temperature differences. Moreover, for small temperature cycles the entrainment region of the oscillator is potentially larger for rectangular pulses. For large temperature shifts we numerically analyze different circadian clock models proposed in the literature with respect to these properties. We observe that for such large temperature shifts sinusoidal or gradual temperature cycles allow a larger entrainment region than rectangular cycles. (paper)

  4. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Slide and Grass Valley Fires, San Bernardino County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Slide and Grass Valley Fires in San Bernardino County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 3.50 inches (88.90 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  5. Coal devolatilization and char conversion under suspension fired conditions in O2/N2 and O2/CO2 atmospheres

    DEFF Research Database (Denmark)

    Jensen, Anker Degn; Brix, Jacob; Jensen, Peter Arendt

    2010-01-01

    have been carried out in an electrically heated entrained flow reactor that is designed to simulate the conditions in a suspension fired boiler. Coal devolatilized in N2 and CO2 atmospheres provided similar results regarding char morphology, char N2-BET surface area and volatile yield. This strongly......The aim of the present investigation is to examine differences between O2/N2 and O2/CO2 atmospheres during devolatilization and char conversion of a bituminous coal at conditions covering temperatures between 1173 K and 1673 K and inlet oxygen concentrations between 5 and 28 vol.%. The experiments...

  6. Investigations of gas entrainment in KNK II

    International Nuclear Information System (INIS)

    Hoppe, P.; Massier, H.; Mitzel, F.; Vaeth, W.

    1979-08-01

    During commissioning of KNK II operational difficulties were encountered due to gas entrainment in the coolant. This gas entrainment caused negative reactivity fluctuations which tripped the reactor repeatedly. Since first investigations indicated one main cause of the gas entrainment and the existence of an accumulation process, a technical modification (installation of a throttle valve) for remedy was performed. This report describes the investigations made after the plant modification. The main objective was to test the effectiveness of the modifications and to look into the following still open problems: Localization of the gas storage, detection and estimation of a permanent gas entrainment and the analysis of positive power overshoots being observed in connection with the gas bubbles

  7. Topflow-experiments on direct condensation and bubble entrainment. Technical report

    International Nuclear Information System (INIS)

    Seidel, Tobias; Lucas, Dirk; Beyer, Matthias

    2016-01-01

    Direct Contact Condensation between steam and water as well as bubble entrainment below the water surface play an important role in different accident scenarios for light water reactors. One example is the emergency core cooling water injection into a two-phase mixture. It has to be considered for example to evaluate potential pressurized thermal shock phenomena. This report documents experiments conducted in flat basin inside the TOPFLOW pressure chamber aiming on the generation of a database useful for CFD model development and validation. It comprises 3 different setups: condensation at a stratified flow of sub-cooled water, condensation at a sub-cooled water jet and a combination of both phenomena with steam bubble entrainment. The documentation includes all details on the experimental set up, on experimental conditions (experimental matrices), on the conduction of the experiments, on measuring techniques used and on data evaluation procedures. In addition, selected results are presented.

  8. Alignment strategies for the entrainment of music and movement rhythms.

    Science.gov (United States)

    Moens, Bart; Leman, Marc

    2015-03-01

    Theories of entrainment assume that spontaneous entrainment emerges from dynamic laws that operate via mediators on interactions, whereby entrainment is facilitated if certain conditions are fulfilled. In this study, we show that mediators can be built that affect the entrainment of human locomotion to music. More specifically, we built D-Jogger, a music player that functions as a mediator between music and locomotion rhythms. The D-Jogger makes it possible to manipulate the timing differences between salient moments of the rhythms (beats and footfalls) through the manipulation of the musical period and phase, which affect the condition in which entrainment functions. We conducted several experiments to explore different strategies for manipulating the entrainment of locomotion and music. The results of these experiments showed that spontaneous entrainment can be manipulated, thereby suggesting different strategies on how to embark. The findings furthermore suggest a distinction among different modalities of entrainment: finding the beat (the most difficult part of entrainment), keeping the beat (easier, as a temporal scheme has been established), and being in phase (no entrainment is needed because the music is always adapted to the human rhythm). This study points to a new avenue of research on entrainment and opens new perspectives for the neuroscience of music. © 2014 New York Academy of Sciences.

  9. Quantifying sources of fine sediment supplied to post-fire debris flows using fallout radionuclide tracers

    Science.gov (United States)

    Smith, Hugh; Sheridan, Gary; Nyman, Petter; Child, David; Lane, Patrick; Hotchkis, Michael

    2013-04-01

    The supply of fine sediment and ash has been identified as an important factor contributing to the initiation of runoff-generated debris flows after fire. However, despite the significance of fines for post-fire debris flow generation, no investigations have sought to quantify sources of this material in debris flow affected catchments. In this study, we employ fallout radionuclides (Cs-137, excess Pb-210 and Pu-239,240) as tracers to measure proportional contributions of fine sediment (bank sources to levee and terminal fan deposits formed by post-fire debris flows in two forest catchments in southeastern Australia. While Cs-137 and excess Pb-210 have been widely used in sediment tracing studies, application of Pu as a tracer represents a recent development and was limited to only one catchment. The estimated range in hillslope surface contributions of fine sediment to individual debris flow deposits in each catchment was 22-69% and 32-74%, respectively. No systematic change in the source contributions to debris flow deposits was observed with distance downstream from channel initiation points. Instead, spatial variability in source contributions was largely influenced by the pattern of debris flow surges forming the deposits. Linking the sediment tracing with interpretation of depositional evidence allowed reconstruction of temporal sequences in sediment source contributions to debris flow surges. Hillslope source inputs dominated most elevated channel deposits such as marginal levees that were formed under peak flow conditions. This indicated the importance of hillslope runoff and sediment supply for debris flow generation in both catchments. In contrast, material stored within channels that was deposited during subsequent surges was predominantly channel-derived. The results demonstrate that fallout radionuclide tracers may provide unique information on the changing source contributions of fine sediment during debris flow events.

  10. Method and apparatus for controlling the flow rate of mercury in a flow system

    Science.gov (United States)

    Grossman, Mark W.; Speer, Richard

    1991-01-01

    A method for increasing the mercury flow rate to a photochemical mercury enrichment utilizing an entrainment system comprises the steps of passing a carrier gas over a pool of mercury maintained at a first temperature T1, wherein the carrier gas entrains mercury vapor; passing said mercury vapor entrained carrier gas to a second temperature zone T2 having temperature less than T1 to condense said entrained mercury vapor, thereby producing a saturated Hg condition in the carrier gas; and passing said saturated Hg carrier gas to said photochemical enrichment reactor.

  11. A hybrid model to predict the onset of gas entrainment with surface tension effects

    International Nuclear Information System (INIS)

    Saleh, W.; Bowden, R.C.; Hassan, I.G.; Kadem, L.

    2008-01-01

    The onset of gas entrainment, in a single downward oriented discharge from a stratified gas-liquid region with was modeled. The assumptions made in the development of the model reduced the problem to that of a potential flow. The discharge was modeled as a point-sink. Through use of the Kelvin-Laplace equation the model included the effects of surface tension. The resulting model required further knowledge of the flow field, specifically the dip radius of curvature prior to the onset of gas entrainment. The dip shape and size was investigated experimentally and correlations were provided to characterize the dip in terms of the discharge Froude number. The experimental correlation was used in conjunction with the theoretical model to predict the critical height. The results showed that by including surface tension effects the predicted critical height showed excellent agreement with experimental data. Surface tension reduces the critical height through the Bond number

  12. Simple estimate of entrainment rate of pollutants from a coastal discharge into the surf zone.

    Science.gov (United States)

    Wong, Simon H C; Monismith, Stephen G; Boehm, Alexandria B

    2013-10-15

    Microbial pollutants from coastal discharges can increase illness risks for swimmers and cause beach advisories. There is presently no predictive model for estimating the entrainment of pollution from coastal discharges into the surf zone. We present a novel, quantitative framework for estimating surf zone entrainment of pollution at a wave-dominant open beach. Using physical arguments, we identify a dimensionless parameter equal to the quotient of the surf zone width l(sz) and the cross-flow length scale of the discharge la = M(j) (1/2)/U(sz), where M(j) is the discharge's momentum flux and U(sz) is a representative alongshore velocity in the surf zone. We conducted numerical modeling of a nonbuoyant discharge at an alongshore uniform beach with constant slope using a wave-resolving hydrodynamic model. Using results from 144 numerical experiments we develop an empirical relationship between the surf zone entrainment rate α and l(sz)/(la). The empirical relationship can reasonably explain seven measurements of surf zone entrainment at three diverse coastal discharges. This predictive relationship can be a useful tool in coastal water quality management and can be used to develop predictive beach water quality models.

  13. Slagging Behavior of Straw and Corn Stover and the Fate of Potassium under Entrained-Flow Gasification Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Leiser, S.; Cieplik, M.K.; Smit, R. [Energy research Centre of the Netherlands ECN, Post Office Box 1, 1755 ZG Petten (Netherlands)

    2013-07-01

    The behavior of straw and corn stover (non-food agricultural residues potentially available for power generation) was studied in a lab-scale reactor under entrained-flow gasification conditions typical for existing integrated gasification combined cycle power systems. This experimental work was assisted by a range of ash-specific analyses and thermodynamic modeling to gain insights into both the physics and chemistry of ash formation and melting behavior. It was observed that, although the major part of the primarily siliceous native ash promptly forms a molten slag, much of the alkalis are evaporated into the syngas. These gas-borne alkalis can potentially cause aerosol formation in the gasifier, gas quench, syngas cooler, and quench systems, resulting in both operating problems (fouling) and emission issues. To minimize the alkali release from straw and corn stover, the addition of an additive (clay) has been proven to be a highly promising method without the negative effects for the melting behavior of the slag.

  14. Determination of thermal characteristics of combustion products of fire-tube heat generator with flow turbulator

    Directory of Open Access Journals (Sweden)

    Lukjanov Alexander V.

    2014-12-01

    Full Text Available Boiler construction is one of the major industries of any state. The aim is to determine the effect of the turbulator on the intensity of heat transfer in the convective part of the fire-tube heat generator of domestic production. The improvement of convective heating surfaces is one of the ways to increase the energy efficiency of the fire-tube heat generator. Since model of the process of heat transfer of gas flow in the convective tubes is multifactorial and does not have clear analytical solution at present, the study of process above is carried out using the experimental method. The results of applying the flow turbulator as a broken tape in the fire-tube heat generator of KV-GM type are presented. On their basis it can be concluded about increasing of heat transfer in convective part of the unit. The use of efficient, reliable, easy to manufacture, relatively inexpensive turbulator in domestic fire-tube heat generators will allow to increase their energy conversion efficiency and reduce fuel consumption, which will have a positive economic effect.

  15. Predicting fire effects on water quality: a perspective and future needs

    Science.gov (United States)

    Smith, Hugh; Sheridan, Gary; Nyman, Petter; Langhans, Christoph; Noske, Philip; Lane, Patrick

    2017-04-01

    Forest environments are a globally significant source of drinking water. Fire presents a credible threat to the supply of high quality water in many forested regions. The post-fire risk to water supplies depends on storm event characteristics, vegetation cover and fire-related changes in soil infiltration and erodibility modulated by landscape position. The resulting magnitude of runoff generation, erosion and constituent flux to streams and reservoirs determines the severity of water quality impacts in combination with the physical and chemical composition of the entrained material. Research to date suggests that most post-fire water quality impacts are due to large increases in the supply of particulates (fine-grained sediment and ash) and particle-associated chemical constituents. The largest water quality impacts result from high magnitude erosion events, including debris flow processes, which typically occur in response to short duration, high intensity storm events during the recovery period. Most research to date focuses on impacts on water quality after fire. However, information on potential water quality impacts is required prior to fire events for risk planning. Moreover, changes in climate and forest management (e.g. prescribed burning) that affect fire regimes may alter water quality risks. Therefore, prediction requires spatial-temporal representation of fire and rainfall regimes coupled with information on fire-related changes to soil hydrologic parameters. Recent work has applied such an approach by combining a fire spread model with historic fire weather data in a Monte Carlo simulation to quantify probabilities associated with fire and storm events generating debris flows and fine sediment influx to a reservoir located in Victoria, Australia. Prediction of fire effects on water quality would benefit from further research in several areas. First, more work on regional-scale stochastic modelling of intersecting fire and storm events with landscape

  16. Hydrodynamics of annular-dispersed flow

    International Nuclear Information System (INIS)

    Ishii, M.; Kataoka, I.

    1982-01-01

    The interfacial drag, droplet entrainment, and droplet size distributions are important for detailed mechanistic modeling of annular dispersed two-phase flow. In view of this, recently developed correlations for these parameters are presented and discussed in this paper. The drag correlations for multiple fluid particle systems have been developed from a similarity hypothesis based on the mixture viscosity model. The results show that the drag coefficient depends on the particle Reynolds number and droplet concentration. The onset on droplet entrainment significantly alters the mechanisms of mass, momentum, and energy transfer between the film and gas core flow as well as the transfer between the two-phase mixture and the wall. By assuming the roll wave entrainment mechanism, the correlations for the amount of entrained droplet as well as for the droplet size distribution have been obtained from a simple model in collaboration with a large number of data

  17. Projected entrainment of fish resulting from aggregate dredging

    International Nuclear Information System (INIS)

    Drabble, Ray

    2012-01-01

    Previous research to assess impacts from aggregate dredging has focussed on infaunal species with few studies made of fish entrainment. Entrainment evidence from hydraulic dredging studies is reviewed to develop a sensitivity index for benthic fish. Environmental monitoring attendant with the granting of new licences in the Eastern Channel Region (ECR) in 2006 offers a unique opportunity to assess the effects of dredging upon fish. Projected theoretical fish entrainment rates are calculated based upon: abundance data from 4m beam trawl sampling of fish species over the period 2005–2008; sensitivity data; and dredging activity and footprint derived from Electronic monitoring System (EMS) data. Results have been compared with actual entrainment rates and also against summary results from independent analysis of the changes in fish population over the period 2005–2008 (). The case is made for entrainment surveys to form part of impact monitoring for marine aggregate dredging.

  18. FPIV study of gas entrainment by a hollow cone spray submitted to variable density

    Energy Technology Data Exchange (ETDEWEB)

    Prosperi, B. [UMR CNRS/INPT-UPS 5502, Institut de Mecanique des Fluides de Toulouse, Toulouse (France); P GS AD INCAS, Siemens VDO Automotive, 1, av Paul Ourliac, BP 1149, Toulouse (France); Delay, G.; Bazile, R. [UMR CNRS/INPT-UPS 5502, Institut de Mecanique des Fluides de Toulouse, Toulouse (France); Helie, J.; Nuglish, H.J. [P GS AD INCAS, Siemens VDO Automotive, 1, av Paul Ourliac, BP 1149, Toulouse (France)

    2007-08-15

    The gas entrainment in a hollow cone spray submitted to variable density is studied experimentally in order to better understand the effect on mixture formation. Particle image velocimetry on fluorescent tracers, associated with a specific processing of the instantaneous velocity fields have been applied to obtain measurement in the close vicinity of the spray edge. In the ''quasi-steady'' region of the spray, important effect of the ambient density on the mass flow rate of entrained gas (m{sub e}) have been pointed out. The axial evolution of m{sub e} is in good agreement with an integral model that takes the momentum exchange between phases into account. (orig.)

  19. An experimental study of particle-driven gravity currents on steep slopes with entrainment of particles

    Directory of Open Access Journals (Sweden)

    M. Rastello

    2002-01-01

    Full Text Available Results of laboratory experiments are presented in which a finite suspension of sawdust particles was released instantaneously into a rectangular channel immersed in a water tank. Two kinds of gravity currents were studied: currents with or without entrainment of particles from the bed. Experiments were repeated for two slopes: 30° and 45°. We observed that the velocity of the front was significantly in-creased as particle entrainment occurred. In addition, our experiments showed that the front kept a quasi-constant velocity for both runs. This might suggest that the flow regime corresponded to the "slumping regime" or "adjustment phase" described earlier by Huppert and Simpson (1980.

  20. Pollutant Removal, Dispersion and Entrainment over Two-Dimensional Idealized Street Canyons: an LES Approach

    Science.gov (United States)

    Wong, C.; Liu, C.

    2010-12-01

    Unlike pollutant transport over flat terrain, the mechanism and plume dispersion over urban areas is not well known. This study is therefore conceived to examine how urban morphology modifies the pollutant transport over urban areas. The computational domain and boundary condition used in this study is shown in Figure 1. The LES shows that inside the street canyon, the ground-level pollutants are carried to roof-level by the re-circulating flow, which are then removed from the street canyon to the UBL. Right above the roof level, narrow high-speed air masses in the streamwise flows and intensive downdrafts have been found in the shear layer. Different from the flows over a smooth surface, the maximum turbulence intensities descend that are peaked near the top of the building roughness. The pollutant is rather uniformly distributed inside a street canyon but disperses rapidly over the buildings exhibiting a Gaussian-plume form in the UBL. The mean component of vertical pollutant flux shows that the mean wind contributes to pollutant removal and entrainment simultaneously. Whereas, the fluctuating component demystifies that pollutant removal is mainly governed by atmospheric turbulence. Over the roof level, atmospheric flows slow down rapidly in the wake behind leeward building, suggesting the momentum entrainment into the street canyons. The decelerating streamwise flows in turn lead to upward flows carrying pollutants away from the street canyons, illustrating the basic pollutant removal mechanism in the skimming flow regime. Figure 1: Computational domain and boundary conditions Figure 2: Ensemble average vertical pollutant flux along the roof level. (a). Mean component; (b). turbulent component.

  1. Development of a program BFQ/VER1 to simulate vapour pull through and liquid entrainment under stratified flow condition

    International Nuclear Information System (INIS)

    Majumdar, P.; Mukhopadyay, D.; Lele, H.G.; Gupta, S.K.

    2000-08-01

    Whether in process industries or nuclear industries, we come across lot of horizontal components, where two-phase or two-component fluids exist in normal or abnormal working conditions. Situations which lead to separation of the phases sees vapour pull through or liquid entrainment phenomena occurring when fluid discharges from horizontal components to the off - take branches. In order to capture the phenomena and applying it to the Indian PHWR during LOCA, a program 'BFQ' has been developed using various models for different fluids and conditions. These models have been validated with various experimental data available in the literature. Smoglie's model has been found to comply with most of the experiments even though it has been developed for air-water system. A modification of the model also been successfully used for feeders located at 45 deg. The result has been well validated with Hassan (1997) experiment for the same configuration. For a typical case of LOCA, RELAP4/MOD6, a widely used Homogenous model for simulating systems, is found to over predict the off-take flow quality from Header under stratified flow condition. (author)

  2. Neural Entrainment to Speech Modulates Speech Intelligibility

    NARCIS (Netherlands)

    Riecke, Lars; Formisano, Elia; Sorger, Bettina; Baskent, Deniz; Gaudrain, Etienne

    2018-01-01

    Speech is crucial for communication in everyday life. Speech-brain entrainment, the alignment of neural activity to the slow temporal fluctuations (envelope) of acoustic speech input, is a ubiquitous element of current theories of speech processing. Associations between speech-brain entrainment and

  3. A study on burning behavior and convective flows in Methanol pool fires bound by ice

    DEFF Research Database (Denmark)

    Farahani, Hamed Farmahini; Jomaas, Grunde; Rangwala, Ali S.

    2017-01-01

    conditions to analyze burning parameters of methanol, 2- in a square glass tray with outside dimensions of 10 × 10 cm and a depth of 5 cm to obtain flow field of methanol pool with a two-dimensional PIV (Particle Image Velocimetry) system. The results of the experiments of the first part show the cold...... of the cavity. The analysis of the results obtained by the PIV system showed the velocity magnitudes and flow patterns in the liquid-phase of icy methanol fire significantly change over the course of burning. In the instants after ignition a horizontal flow induced by Marangoni near the surface was observed......An experimental study on methanol pool fires bound by ice was carried to research the burning behavior and flow field (within the liquid-phase) of methanol. The experiments were conducted in two parts: 1- in a cylindrical ice cavity/pan (10.2 cm diameter and 6 cm depth) at three different...

  4. Thermal/chemical degradation of ceramic cross-flow filter materials

    Energy Technology Data Exchange (ETDEWEB)

    Alvin, M.A.; Lane, J.E.; Lippert, T.E.

    1989-11-01

    This report summarizes the 14-month, Phase 1 effort conducted by Westinghouse on the Thermal/Chemical Degradation of Ceramic Cross-Flow Filter Materials program. In Phase 1 expected filter process conditions were identified for a fixed-bed, fluid-bed, and entrained-bed gasification, direct coal fired turbine, and pressurized fluidized-bed combustion system. Ceramic cross-flow filter materials were also selected, procured, and subjected to chemical and physical characterization. The stability of each of the ceramic cross-flow materials was assessed in terms of potential reactions or phase change as a result of process temperature, and effluent gas compositions containing alkali and fines. In addition chemical and physical characterization was conducted on cross-flow filters that were exposed to the METC fluid-bed gasifier and the New York University pressurized fluidized-bed combustor. Long-term high temperature degradation mechanisms were proposed for each ceramic cross-flow material at process operating conditions. An experimental bench-scale test program is recommended to be conducted in Phase 2, generating data that support the proposed cross-flow filter material thermal/chemical degradation mechanisms. Papers on the individual subtasks have been processed separately for inclusion on the data base.

  5. Experiment study on NOx reduction through biomass reburning in an entrained flow reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lu, P.; Wang, Y.; Lu, F.; Liu, Y. [Nanjing Normal Univ. (China). School of Energy and Mechanical Engineering

    2013-07-01

    The reburning experiments with six kinds of biomass (including rice straw, wheat straw, maize stalk, cotton stalk, rice husk and bagasse,) and one biochar (wheat straw char) was carried out in an entrained flow reactor. The effects of biomass type, stoichiometric ratio in the reburning-zone (SR2), reaction temperature in the reburning-zone (t{sub 2}), particle sizes of biomass (d{sub p}), and reburning fuel fraction (R{sub ff}) on NO reduction efficiency analysed. The NO heterogeneous reduction contribute of biochar was also analyzed. The results indicate that NO reduction efficiency behaves a trend of first increase and then decrease with decreasing of SR2 or increasing of R{sub ff}. The higher NO reduction efficiency (more than 50%) can be achieved at the range of SR2 = 0.7-0.8 or R{sub ff} = 20-26% during reburning with six tested biomass. Cotton stalk with higher volatiles and the highest contents of K, Na alkali metals behaves the best performance of NO reduction. In the range of t{sub 2} = 900-1,100 C NO reduction efficiency increases with increasing of reburning-zone reaction temperature at the same SR2. NO reduction efficiency increases insignificantly with decreasing of particle size of biomass while d{sub p} < 425{mu}m. The contribution of NO heterogeneous reduction by wheat straw char to the total NO reduction is in the higher range of 59-68% while R{sub ff} = 10-26%.

  6. Dynamic Analysis of a Rotor System Supported on Squeeze Film Damper with Air Entrainment

    Science.gov (United States)

    Zhang, Wei; Han, Bingbing; Zhang, Kunpeng; Ding, Qian

    2017-12-01

    Squeeze film dampers (SFDs) are widely used in compressors and turbines to suppress the vibration while traversing critical speeds. In practical applications, air ingestion from the outside environment and cavitation may lead to a foamy lubricant that weakens oil film damping and dynamic performance of rotor system. In this paper, a rigid rotor model is established considering both lateral and pitching vibration under different imbalance excitations to evaluate the effect of air entrainment on rotor system. Tests with three different imbalances are carried out on a rotor-SFD apparatus. Volume controlled air in mixture ranging from pure oil to all air are supplied to the SFD. The transient response of rotor is measured in the experiments. The results show that two-phase flow produces significant influence on the system stability and dynamical response. The damping properties are weakened by entrained air, such as the damping on high frequency components of rolling ball bearing. Super-harmonic resonance and bifurcation are observed, as well as the low frequency components due to air entrainment.

  7. Experimental study on combustion and suppression characteristics of sodium fire in a columnar flow using extinguishing powder

    International Nuclear Information System (INIS)

    Huo Yan; Zhang Zhigang; Li Jinke; Liu Zhongkun; Ma Yaolong

    2017-01-01

    In the operation of the sodium-cooled fast reactor, the leakage and fire accident of liquid sodium is common and it is frequent in sodium-related facilities. This study focuses on the combustion and suppression characteristics of sodium fire in a columnar flow. Liquid sodium (250°C) is injected into a 7.9 m"3 cylindrical chamber at a flow rate of about 1.0 m"3/h to create a columnar sodium fire, and 18.4 kg class D extinguishing powder is sprayed after the liquid sodium injection. The temperature in the chamber space and sodium collection plate and the heat release rate from sodium fire are measured and analyzed. Based on the temperature data the sodium fire under suppression could be divided into four phases of dropping sharply, continuously remaining lower, rising and declining mildly, and depressing. The sodium fire in the space could be suppressed and cooled down if the extinguishing agent could spray in the early period of the liquid sodium injection. The extinguishing agent could suppress the combustion and spreading of liquid sodium dropping on the collection plate, limit the pool combustion area and postpone the commencement of sodium pool burning in spite of its later re-ignition happening. This study promises to evaluate the combustion and suppression characteristics of sodium fire in the sodium-related facilities. (author)

  8. On a criterion of incipient motion and entrainment into suspension of a particle from cuttings bed in shear flow of non-Newtonian fluid

    Science.gov (United States)

    Ignatenko, Yaroslav; Bocharov, Oleg; May, Roland

    2017-10-01

    Solids transport is a major issue in high angle wells. Bed-load forms by sediment while transport and accompanied by intermittent contact with stream-bed by rolling, sliding and bouncing. The study presents the results of a numerical simulation of a laminar steady-state flow around a particle at rest and in free motion in a shear flow of Herschel-Bulkley fluid. The simulation was performed using the OpenFOAM open-source CFD package. A criterion for particle incipient motion and entrainment into suspension from cuttings bed (Shields criteria) based on forces and torques balance is discussed. Deflection of the fluid parameters from the ones of Newtonian fluid leads to decreasing of the drag and lift forces and the hydrodynamic moment. Thus, the critical shear stress (Shields parameter) for the considered non-Newtonian fluid must be greater than the one for a Newtonian fluid.

  9. Assessment of impact due to entrainment of ichthyoplankton

    International Nuclear Information System (INIS)

    Horst, T.J.

    1975-01-01

    Three approaches to the assessment of impact associated with the entrainment of ichthyoplankton into power stations are discussed. The first is the estimation of the probability of mortality for those organisms entrained. The second is the assessment to the fish populations which have the egg and larvae life stages entrained. The third approach is the assessment of impact to the community or ecosystem. Some models are presented as examples for each of the three approaches. (U.S.)

  10. Observations of debris flows at Chalk Cliffs, Colorado, USA: Part 1, in-situ measurements of flow dynamics, tracer particle movement and video imagery from the summer of 2009

    Science.gov (United States)

    McCoy, Scott W.; Coe, Jeffrey A.; Kean, Jason W.; Tucker, Greg E.; Staley, Dennis M.; Wasklewicz, Thad A.

    2011-01-01

    Debris flows initiated by surface-water runoff during short duration, moderate- to high-intensity rainfall are common in steep, rocky, and sparsely vegetated terrain. Yet large uncertainties remain about the potential for a flow to grow through entrainment of loose debris, which make formulation of accurate mechanical models of debris-flow routing difficult. Using a combination of in situ measurements of debris flow dynamics, video imagery, tracer rocks implanted with passive integrated transponders (PIT) and pre- and post-flow 2-cm resolution digital terrain models (terrain data presented in a companion paper by STALEY et alii, 2011), we investigated the entrainment and transport response of debris flows at Chalk Cliffs, CO, USA. Four monitored events during the summer of 2009 all initiated from surface-water runoff, generally less than an hour after the first measurable rain. Despite reach-scale morphology that remained relatively constant, the four flow events displayed a range of responses, from long-runout flows that entrained significant amounts of channel sediment and dammed the main-stem river, to smaller, short-runout flows that were primarily depositional in the upper basin. Tracer-rock travel-distance distributions for these events were bimodal; particles either remained immobile or they travelled the entire length of the catchment. The long-runout, large-entrainment flow differed from the other smaller flows by the following controlling factors: peak 10-minute rain intensity; duration of significant flow in the channel; and to a lesser extent, peak surge depth and velocity. Our growing database of natural debris-flow events can be used to develop linkages between observed debris-flow transport and entrainment responses and the controlling rainstorm characteristics and flow properties.

  11. Differential entrainment of neuroelectric delta oscillations in developmental dyslexia.

    Directory of Open Access Journals (Sweden)

    Fruzsina Soltész

    Full Text Available Oscillatory entrainment to the speech signal is important for language processing, but has not yet been studied in developmental disorders of language. Developmental dyslexia, a difficulty in acquiring efficient reading skills linked to difficulties with phonology (the sound structure of language, has been associated with behavioural entrainment deficits. It has been proposed that the phonological 'deficit' that characterises dyslexia across languages is related to impaired auditory entrainment to speech at lower frequencies via neuroelectric oscillations (<10 Hz, 'temporal sampling theory'. Impaired entrainment to temporal modulations at lower frequencies would affect the recovery of the prosodic and syllabic structure of speech. Here we investigated event-related oscillatory EEG activity and contingent negative variation (CNV to auditory rhythmic tone streams delivered at frequencies within the delta band (2 Hz, 1.5 Hz, relevant to sampling stressed syllables in speech. Given prior behavioural entrainment findings at these rates, we predicted functionally atypical entrainment of delta oscillations in dyslexia. Participants performed a rhythmic expectancy task, detecting occasional white noise targets interspersed with tones occurring regularly at rates of 2 Hz or 1.5 Hz. Both groups showed significant entrainment of delta oscillations to the rhythmic stimulus stream, however the strength of inter-trial delta phase coherence (ITC, 'phase locking' and the CNV were both significantly weaker in dyslexics, suggestive of weaker entrainment and less preparatory brain activity. Both ITC strength and CNV amplitude were significantly related to individual differences in language processing and reading. Additionally, the instantaneous phase of prestimulus delta oscillation predicted behavioural responding (response time for control participants only.

  12. Nonassociative learning promotes respiratory entrainment to mechanical ventilation.

    Directory of Open Access Journals (Sweden)

    Shawna M MacDonald

    Full Text Available BACKGROUND: Patient-ventilator synchrony is a major concern in critical care and is influenced by phasic lung-volume feedback control of the respiratory rhythm. Routine clinical application of positive end-expiratory pressure (PEEP introduces a tonic input which, if unopposed, might disrupt respiratory-ventilator entrainment through sustained activation of the vagally-mediated Hering-Breuer reflex. We suggest that this potential adverse effect may be averted by two differentiator forms of nonassociative learning (habituation and desensitization of the Hering-Breuer reflex via pontomedullary pathways. METHODOLOGY/PRINCIPAL FINDINGS: We tested these hypotheses in 17 urethane-anesthetized adult Sprague-Dawley rats under controlled mechanical ventilation. Without PEEP, phrenic discharge was entrained 1:1 to the ventilator rhythm. Application of PEEP momentarily dampened the entrainment to higher ratios but this effect was gradually adapted by nonassociative learning. Bilateral electrolytic lesions of the pneumotaxic center weakened the adaptation to PEEP, whereas sustained stimulation of the pneumotaxic center weakened the entrainment independent of PEEP. In all cases, entrainment was abolished after vagotomy. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate an important functional role for pneumotaxic desensitization and extra-pontine habituation of the Hering-Breuer reflex elicited by lung inflation: acting as buffers or high-pass filters against tonic vagal volume input, these differentiator forms of nonassociative learning help to restore respiratory-ventilator entrainment in the face of PEEP. Such central sites-specific habituation and desensitization of the Hering-Breuer reflex provide a useful experimental model of nonassociative learning in mammals that is of particular significance in understanding respiratory rhythmogenesis and coupled-oscillator entrainment mechanisms, and in the clinical management of mechanical ventilation in

  13. Characterization of liquid entrainment in the AP1000 automatic depressurization system from APEX tests

    International Nuclear Information System (INIS)

    Richard F Wright; Terry L Schulz; Jose N Reyes; John Groome

    2005-01-01

    -phase flow in the ADS-4, and to quantify the liquid entrainment at high decay power conditions representing the time of ADS-4 actuation, and at low decay power conditions representing the time of IRWST and sump injection. For the higher power levels, the tests show that as long as core makeup water is available, the two phase mixture level remains at the hot leg elevation, and a significant amount of liquid is entrained out the ADS-4 lines. As the makeup flow is decreased (at a given power level), the collapsed liquid level decreased as the core exit void fraction increased, but the two-phase level remains in the hot leg. If the makeup flow is stopped, the two-phase level falls below the hot leg elevation, and the liquid entrainment is markedly reduced. At the low power levels, the core makeup flow is sufficient to assure that the two-phase mixture level remains at the hot leg elevation, and significant liquid entrainment is observed even at very low steam velocities. (authors)

  14. Updated logistic regression equations for the calculation of post-fire debris-flow likelihood in the western United States

    Science.gov (United States)

    Staley, Dennis M.; Negri, Jacquelyn A.; Kean, Jason W.; Laber, Jayme L.; Tillery, Anne C.; Youberg, Ann M.

    2016-06-30

    Wildfire can significantly alter the hydrologic response of a watershed to the extent that even modest rainstorms can generate dangerous flash floods and debris flows. To reduce public exposure to hazard, the U.S. Geological Survey produces post-fire debris-flow hazard assessments for select fires in the western United States. We use publicly available geospatial data describing basin morphology, burn severity, soil properties, and rainfall characteristics to estimate the statistical likelihood that debris flows will occur in response to a storm of a given rainfall intensity. Using an empirical database and refined geospatial analysis methods, we defined new equations for the prediction of debris-flow likelihood using logistic regression methods. We showed that the new logistic regression model outperformed previous models used to predict debris-flow likelihood.

  15. Mattagami River Lake sturgeon entrainment : Little Long generating station facilities

    International Nuclear Information System (INIS)

    Seyler, J.; Evers, J.; McKinley, S.; Evans, R.R.; Prevost, G.; Carson, R.; Phoenix, D.

    1996-01-01

    This project and publication is the result of a collaborative effort by other Large River Ecosystem Unit of Northeast Science (NEST), Ontario Hydro in Kapuskasing, and the New Post First Nation in Cochrane, Ontario, designed to investigate potential solutions to minimize or eliminate the problem of trapped lake sturgeon in the Adam Creek Diversion. The Adam Creek Dam is used to divert excess water from the Mattagami River hydroelectric complex which consists of the Little Long, Smoky Falls, Harmon and Kipling generating stations. The lake sturgeon entrainment problem in the area was discovered in 1990. Potential solutions to the problem include the redirection of flows to mainstream, the placement of a rope barrier, electrical deterrents, physical/electrical guidance systems, sound deterrents, gate modifications, and the continued relocation of fish. The advantages and disadvantages of each of these potential solutions are discussed. Results of the analysis indicated that perceptual and physical barriers have the greatest potential to minimize lake sturgeon entrainment in Adam Creek. 25 refs., 2 tabs., 3 figs., 6 appendices

  16. Review and investigations of oscillatory flow behaviour of a horizontal ceiling opening for nuclear containment and fire safety analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, P.K.; Singh, R.K.; Ghosh, A.K. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Reactor Safety Div.

    2011-05-15

    In the thermal hydraulics codes developed for fire safety analysis and for containment thermal hydraulic analysis, junctions in the multi-compartment geometries is often modeled as uni-directional junctions. However, ceiling junctions are known to depict unstable/oscillatory bi-directional flow behavior. Detailed investigations have been carried out to understand the unstable flow behaviour of a junction by analyzing an earlier reported experiment and its subsequent two dimensional numerical RANS based study of fire in an enclosure. The authors attempt more realistic and desired three dimensional and inherently transient large eddy simulations using a computer code Fire Dynamics Simulator (FDS). The paper presents the details of the analysis, the results obtained and further studies required to be conducted so that the findings can be applied to the fire/containment thermal hydraulics analysis codes successfully. (orig.)

  17. Effects of the proposed California WaterFix North Delta Diversion on flow reversals and entrainment of juvenile Chinook salmon (Oncorhynchus tshawytscha) into Georgiana Slough and the Delta Cross Channel, northern California

    Science.gov (United States)

    Perry, Russell W.; Romine, Jason G.; Pope, Adam C.; Evans, Scott D.

    2018-02-27

    The California Department of Water Resources and Bureau of Reclamation propose new water intake facilities on the Sacramento River in northern California that would convey some of the water for export to areas south of the Sacramento-San Joaquin River Delta (hereinafter referred to as the Delta) through tunnels rather than through the Delta. The collection of water intakes, tunnels, pumping facilities, associated structures, and proposed operations are collectively referred to as California WaterFix. The water intake facilities, hereinafter referred to as the North Delta Diversion (NDD), are proposed to be located on the Sacramento River downstream of the city of Sacramento and upstream of the first major river junction where Sutter Slough branches from the Sacramento River. The NDD can divert a maximum discharge of 9,000 cubic feet per second (ft3/s) from the Sacramento River, which reduces the amount of Sacramento River inflow into the Delta.In this report, we conducted three analyses to investigate the effect of the NDD and its proposed operation on entrainment of juvenile Chinook salmon (Oncorhynchus tshawytscha) into Georgiana Slough and the Delta Cross Channel (DCC). Fish that enter the interior Delta (the network of channels to the south of the Sacramento River) through Georgiana Slough and the DCC survive at lower rates than fish that use other migration routes (Sacramento River, Sutter Slough, and Steamboat Slough). Therefore, fisheries managers were concerned about the extent to which operation of the NDD would increase the proportion of the population entering the interior Delta, which, all else being equal, would lower overall survival through the Delta by increasing the fraction of the population subject to lower survival rates. Operation of the NDD would reduce flow in the Sacramento River, which has the potential to increase the magnitude and duration of reverse flows of the Sacramento River downstream of Georgiana Slough.In the first analysis, we

  18. Entrainment and high-density three-dimensional mapping in right atrial macroreentry provide critical complementary information: Entrainment may unmask "visual reentry" as passive.

    Science.gov (United States)

    Pathik, Bhupesh; Lee, Geoffrey; Nalliah, Chrishan; Joseph, Stephen; Morton, Joseph B; Sparks, Paul B; Sanders, Prashanthan; Kistler, Peter M; Kalman, Jonathan M

    2017-10-01

    With the recent advent of high-density (HD) 3-dimensional (3D) mapping, the utility of entrainment is uncertain. However, the limitations of visual representation and interpretation of these high-resolution 3D maps are unclear. The purpose of this study was to determine the strengths and limitations of both HD 3D mapping and entrainment mapping during mapping of right atrial macroreentry. Fifteen patients were studied. The number and type of circuits accounting for ≥90% of the tachycardia cycle length using HD 3D mapping were verified using systematic entrainment mapping. Entrainment sites with an unexpectedly long postpacing interval despite proximity to the active circuit were evaluated. Based on HD 3D mapping, 27 circuits were observed: 12 peritricuspid, 2 upper loop reentry, 10 lower loop reentry, and 3 lateral wall circuits. With entrainment, 17 of the 27 circuits were active: all 12 peritricuspid and 2 upper loop reentry. However, lower loop reentry was confirmed in only 3 of 10, and none of the 3 lateral wall circuits were present. Mean percentage of tachycardia cycle length covered by active circuits was 98% ± 1% vs 97% ± 2% for passive circuits (P = .09). None of the 345 entrainment runs terminated tachycardia or changed tachycardia mechanism. In 8 of 15 patients, 13 examples of unexpectedly long postpacing interval were observed at entrainment sites located distal to localized zones of slow conduction seen on HD 3D mapping. Using HD 3D mapping, "visual reentry" may be due to passive circuitous propagation rather than a critical reentrant circuit. HD 3D mapping provides new insights into regional conduction and helps explain unusual entrainment phenomena. Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  19. Volatility and entrainment of feed components and product glass characteristics during pilot-scale vitrification of simulated Hanford site low-level waste

    International Nuclear Information System (INIS)

    Shade, J.W.

    1996-01-01

    Commercially available melter technologies were tested for application to vitrification of Hanford site low-level waste (LLW). Testing was conducted at vendor facilities using a non-radioactive LLW simulant. Technologies tested included four Joule-heated melter types, a carbon electrode melter, a cyclone combustion melter, and a plasma torch-fired melter. A variety of samples were collected during the vendor tests and analyzed to provide data to support evaluation of the technologies. This paper describes the evaluation of melter feed component volatility and entrainment losses and product glass samples produced during the vendor tests. All vendors produced glasses that met minimum leach criteria established for the test glass formulations, although in many cases the waste oxide loading was less than intended. Entrainment was much lower in Joule-heated systems than in the combustion or plasma torch-fired systems. Volatility of alkali metals, halogens, B, Mo, and P were severe for non-Joule-heated systems. While losses of sulfur were significant for all systems, the volatility of other components was greatly reduced for some configurations of Joule-heated melters. Data on approaches to reduce NO x generation, resulting from high nitrate and nitrite content in the double-shell slurry feed, are also presented

  20. Compartment modeling of coal gasification in an entrained flow gasifier: A study on the influence of operating conditions

    International Nuclear Information System (INIS)

    Kong, Xiangdong; Zhong, Weimin; Du, Wenli; Qian, Feng

    2014-01-01

    Highlights: • Gasification of Shenfu coal in an industrial Texaco gasifier for syngas production. • An equivalent compartment model is developed using Aspen Plus. • Effects of operating parameters on gasification performance indices are studied. • Choosing a reasonable ROC to enhance the gasification efficiency can be flexible. - Abstract: Coal gasifiers are core components of coal-based polygeneration systems for power and chemical production. To study the effects of operational parameters on the performance of entrained flow coal gasifiers, this paper presents an equivalent compartment model (CM) using the Aspen Plus process simulator. The CM blocking is established based on gasifier flow field analysis, using a number of compartments. A simple configuration of these compartments involving material recirculation should be able to simulate the main flow and provide the temperature and gas component distributions. The model predictions exhibit good agreement with industrial data in the model validation. The influences of the oxygen-to-carbon ratio (ROC) and the coal slurry concentration on the gasification performance are discussed. Within the calculation range, the increase in the coal slurry concentration enhances the yield of the effective compositions in product gas. For a given slurry concentration of 62%, the efficient gas yield is a maximum for ROC of 1.43 kg/kg, whereas the oxygen consumption is a minimum for ROC of 1.37 kg/kg. According to the intended final use, however, choosing a reasonable ROC to obtain a higher efficient syngas yield and lower oxygen consumption can be flexible

  1. Annular dispersed flow analysis model by Lagrangian method and liquid film cell method

    International Nuclear Information System (INIS)

    Matsuura, K.; Kuchinishi, M.; Kataoka, I.; Serizawa, A.

    2003-01-01

    A new annular dispersed flow analysis model was developed. In this model, both droplet behavior and liquid film behavior were simultaneously analyzed. Droplet behavior in turbulent flow was analyzed by the Lagrangian method with refined stochastic model. On the other hand, liquid film behavior was simulated by the boundary condition of moving rough wall and liquid film cell model, which was used to estimate liquid film flow rate. The height of moving rough wall was estimated by disturbance wave height correlation. In each liquid film cell, liquid film flow rate was calculated by considering droplet deposition and entrainment flow rate. Droplet deposition flow rate was calculated by Lagrangian method and entrainment flow rate was calculated by entrainment correlation. For the verification of moving rough wall model, turbulent flow analysis results under the annular flow condition were compared with the experimental data. Agreement between analysis results and experimental results were fairly good. Furthermore annular dispersed flow experiments were analyzed, in order to verify droplet behavior model and the liquid film cell model. The experimental results of radial distribution of droplet mass flux were compared with analysis results. The agreement was good under low liquid flow rate condition and poor under high liquid flow rate condition. But by modifying entrainment rate correlation, the agreement become good even under high liquid flow rate. This means that basic analysis method of droplet and liquid film behavior was right. In future work, verification calculation should be carried out under different experimental condition and entrainment ratio correlation also should be corrected

  2. Low NOx combustion and SCR flow field optimization in a low volatile coal fired boiler.

    Science.gov (United States)

    Liu, Xing; Tan, Houzhang; Wang, Yibin; Yang, Fuxin; Mikulčić, Hrvoje; Vujanović, Milan; Duić, Neven

    2018-08-15

    Low NO x burner redesign and deep air staging have been carried out to optimize the poor ignition and reduce the NO x emissions in a low volatile coal fired 330 MW e boiler. Residual swirling flow in the tangentially-fired furnace caused flue gas velocity deviations at furnace exit, leading to flow field unevenness in the SCR (selective catalytic reduction) system and poor denitrification efficiency. Numerical simulations on the velocity field in the SCR system were carried out to determine the optimal flow deflector arrangement to improve flow field uniformity of SCR system. Full-scale experiment was performed to investigate the effect of low NO x combustion and SCR flow field optimization. Compared with the results before the optimization, the NO x emissions at furnace exit decreased from 550 to 650 mg/Nm³ to 330-430 mg/Nm³. The sample standard deviation of the NO x emissions at the outlet section of SCR decreased from 34.8 mg/Nm³ to 7.8 mg/Nm³. The consumption of liquid ammonia reduced from 150 to 200 kg/h to 100-150 kg/h after optimization. Copyright © 2018. Published by Elsevier Ltd.

  3. Postwildfire debris flows hazard assessment for the area burned by the 2011 Track Fire, northeastern New Mexico and southeastern Colorado

    Science.gov (United States)

    Tillery, Anne C.; Darr, Michael J.; Cannon, Susan H.; Michael, John A.

    2011-01-01

    In June 2011, the Track Fire burned 113 square kilometers in Colfax County, northeastern New Mexico, and Las Animas County, southeastern Colorado, including the upper watersheds of Chicorica and Raton Creeks. The burned landscape is now at risk of damage from postwildfire erosion, such as that caused by debris flows and flash floods. This report presents a preliminary hazard assessment of the debris-flow potential from basins burned by the Track Fire. A pair of empirical hazard-assessment models developed using data from recently burned basins throughout the intermountain western United States were used to estimate the probability of debris-flow occurrence and volume of debris flows at the outlets of selected drainage basins within the burned area. The models incorporate measures of burn severity, topography, soils, and storm rainfall to estimate the probability and volume of post-fire debris flows following the fire. In response to a design storm of 38 millimeters of rain in 30 minutes (10-year recurrence-interval), the probability of debris flow estimated for basins burned by the Track fire ranged between 2 and 97 percent, with probabilities greater than 80 percent identified for the majority of the tributary basins to Raton Creek in Railroad Canyon; six basins that flow into Lake Maloya, including the Segerstrom Creek and Swachheim Creek basins; two tributary basins to Sugarite Canyon, and an unnamed basin on the eastern flank of the burned area. Estimated debris-flow volumes ranged from 30 cubic meters to greater than 100,000 cubic meters. The largest volumes (greater than 100,000 cubic meters) were estimated for Segerstrom Creek and Swachheim Creek basins, which drain into Lake Maloya. The Combined Relative Debris-Flow Hazard Ranking identifies the Segerstrom Creek and Swachheim Creek basins as having the highest probability of producing the largest debris flows. This finding indicates the greatest post-fire debris-flow impacts may be expected to Lake Maloya

  4. Investigation of effect of stopping supply flow into the cell on the confinement of the radioactive materials under fire accident

    International Nuclear Information System (INIS)

    Abe, Hitoshi; Watanabe, Koji

    1999-03-01

    On November 20th 1997, a fire accident happened at Uranium Enrichment Research Laboratory, Tokai, Japan Atomic Energy Research Institute and ventilation filters in the laboratory clogged. When fire accident occurs in a controlled area, a large quantity of smoke generates in the area and dropping exhaust flow from the area by the clogging of ventilation filters and rising pressure in the area are caused. Moreover, leakage of smoke including radioactive materials from the area by the pressure rising is expected. To prevent the leakage, it is expected that stopping supply flow to the area during a fire accident is effective, however, quantitative evaluation about this effect has not been performed. By using CELVA-1D code, one-dimensional thermofluid analysis code, this effect is evaluated quantitatively by modeling the laboratory and estimating source terms released during the fire accident. As the results, it has been found that the efficiency of confinement of the radioactive materials into the area is preserved in the slightly long period of time in case of stopping supply flow to the area, however, this effect can be neglected in case that scale of fire accident is relatively large. (author)

  5. Aerosol entrainment from a sparged non-Newtonian slurry

    International Nuclear Information System (INIS)

    Fritz, Brad G.

    2006-01-01

    Aerosol measurements were conducted above a half-scale air sparged mixing tank filled with simulated waste slurry. Three aerosol size fractions were measured at three sampling heights at three different sparging rates using a filter based ambient air sampling technique. Aerosol concentrations in the head space above the closed tank demonstrated a wide range, varying between 97 ?g m-3 for PM2.5 and 5650 ?g m-3 for TSP. The variation in concentrations was a function of sampling heights, size fraction and sparging rate. Measured aerosol entrainment coefficients showed good agreement with existing entrainment models. The models evaluated generally over predicted the entrainment, but were within a factor of two of the measured entrainment. This indicates that the range of applicability of the models may be extendable to include sparged slurries with Bingham plastic rheological properties

  6. Broadening of cloud droplet spectra through turbulent entrainment and eddy hopping

    Science.gov (United States)

    Abade, Gustavo; Grabowski, Wojciech; Pawlowska, Hanna

    2017-11-01

    This work discusses the effect of cloud turbulence and turbulent entrainment on the evolution of the cloud droplet-size spectrum. We simulate an ensemble of idealized turbulent cloud parcels that are subject to entrainment events, modeled as a random Poisson process. Entrainment events, subsequent turbulent mixing inside the parcel, supersaturation fluctuations, and the resulting stochastic droplet growth by condensation are simulated using a Monte Carlo scheme. Quantities characterizing the turbulence intensity, entrainment rate and the mean fraction of environmental air entrained in an event are specified as external parameters. Cloud microphysics is described by applying Lagrangian particles, the so-called superdroplets. They are either unactivated cloud condensation nuclei (CCN) or cloud droplets that form from activated CCN. The model accounts for the transport of environmental CCN into the cloud by the entraining eddies at the cloud edge. Turbulent mixing of the entrained dry air with cloudy air is described using a linear model. We show that turbulence plays an important role in aiding entrained CCN to activate, providing a source of small cloud droplets and thus broadening the droplet size distribution. Further simulation results will be reported at the meeting.

  7. Fire Behavior System for the Full Range of Fire Management Needs

    Science.gov (United States)

    Richard C. Rothermel; Patricia L. Andrews

    1987-01-01

    An "integrated fire behavior/fire danger rating system" should be "seamless" to avoid requiring choices among alternate, independent systems. Descriptions of fuel moisture, fuels, and fire behavior should be standardized, permitting information to flow easily through the spectrum of fire management needs. The level of resolution depends on the...

  8. Debris flow run-out simulation and analysis using a dynamic model

    Science.gov (United States)

    Melo, Raquel; van Asch, Theo; Zêzere, José L.

    2018-02-01

    Only two months after a huge forest fire occurred in the upper part of a valley located in central Portugal, several debris flows were triggered by intense rainfall. The event caused infrastructural and economic damage, although no lives were lost. The present research aims to simulate the run-out of two debris flows that occurred during the event as well as to calculate via back-analysis the rheological parameters and the excess rain involved. Thus, a dynamic model was used, which integrates surface runoff, concentrated erosion along the channels, propagation and deposition of flow material. Afterwards, the model was validated using 32 debris flows triggered during the same event that were not considered for calibration. The rheological and entrainment parameters obtained for the most accurate simulation were then used to perform three scenarios of debris flow run-out on the basin scale. The results were confronted with the existing buildings exposed in the study area and the worst-case scenario showed a potential inundation that may affect 345 buildings. In addition, six streams where debris flow occurred in the past and caused material damage and loss of lives were identified.

  9. The role of episodic fire-related debris flows on long-term (103-104) sediment yields in the Middle Fork Salmon River Watershed, in central Idaho

    Science.gov (United States)

    Riley, K. E.; Pierce, J. L.; Hopkins, A.

    2010-12-01

    Episodic fire-related debris flows contribute large amounts of sediment and large woody debris to streams. This study evaluates fire-related sedimentation from small steep tributaries of the Middle Fork Salmon River (MFSR) in central Idaho to evaluate the timing, frequency, and magnitude of episodic fire-related sedimentation on long-term (10 3-10 4) sediment yields. The MFSR lies within the Northern Rocky Mountains and encompasses a range of ecosystems including high elevation (~3,000 -1,700 m) subalpine pine and spruce forests, mid-elevation (2650 - 1130 m) montane Douglas-fir and ponderosa pine-dominated forests and low elevation (~ 1,800 - 900 m) sagebrush steppe. Recent debris flow events in tributaries of the MFSR appear to primarily result from increased surface runoff, rilling, and progressive sediment bulking following high severity fires. This study estimates: 1) the volume of sediment delivered by four recent (1997-2008) fire-related debris flow events using real time kinematic GPS surveys, and 2) the timing of Holocene fire-related debris flow events determined by 14C dating charcoal fragments preserved in buried burned soils and within fire-related deposits. Our measured volumes of the four recent debris flow events are compared to two empirically derived volume estimates based on remotely sensed spatial data (burn severity and slope), measured geometric data (longitudinal profile, cross sectional area, flow banking angle), and precipitation records. Preliminary stratigraphic profiles in incised alluvial fans suggest that a large percentage of alluvial fan thickness is composed of fire-related deposits suggesting fire-related hillslope erosion is a major process delivering sediment to alluvial fans and to the MFSR. Fire-related deposits from upper basins compose ~71% of total alluvial fan thickness, while fire-related deposits from lower basins make up 36% of alluvial fan thickness. However, lower basins are less densely vegetated with small diameter

  10. Musical Entrainment Subsumes Bodily Gestures – Its Definition Needs a Spatiotemporal Dimension

    Directory of Open Access Journals (Sweden)

    Marc Leman

    2012-09-01

    Full Text Available In his paper “What is entrainment? Definition and applications in musical research” (this issue, M. Clayton offers a definition of entrainment that is based on a timing dimension (relative phase relationships. However, this definition may be too limited when applied to musical entrainment. Based on the idea that human engagement with music is embodied and that gestures may condition entrainment, I suggest that the definition of entrainment be broadened so as to include a spatiotemporal dimension.

  11. Speech Entrainment Compensates for Broca's Area Damage

    Science.gov (United States)

    Fridriksson, Julius; Basilakos, Alexandra; Hickok, Gregory; Bonilha, Leonardo; Rorden, Chris

    2015-01-01

    Speech entrainment (SE), the online mimicking of an audiovisual speech model, has been shown to increase speech fluency in patients with Broca's aphasia. However, not all individuals with aphasia benefit from SE. The purpose of this study was to identify patterns of cortical damage that predict a positive response SE's fluency-inducing effects. Forty-four chronic patients with left hemisphere stroke (15 female) were included in this study. Participants completed two tasks: 1) spontaneous speech production, and 2) audiovisual SE. Number of different words per minute was calculated as a speech output measure for each task, with the difference between SE and spontaneous speech conditions yielding a measure of fluency improvement. Voxel-wise lesion-symptom mapping (VLSM) was used to relate the number of different words per minute for spontaneous speech, SE, and SE-related improvement to patterns of brain damage in order to predict lesion locations associated with the fluency-inducing response to speech entrainment. Individuals with Broca's aphasia demonstrated a significant increase in different words per minute during speech entrainment versus spontaneous speech. A similar pattern of improvement was not seen in patients with other types of aphasia. VLSM analysis revealed damage to the inferior frontal gyrus predicted this response. Results suggest that SE exerts its fluency-inducing effects by providing a surrogate target for speech production via internal monitoring processes. Clinically, these results add further support for the use of speech entrainment to improve speech production and may help select patients for speech entrainment treatment. PMID:25989443

  12. Kinetics of devolatilization and oxidation of a pulverized biomass in an entrained flow reactor under realistic combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, Santiago [LITEC-CSIC (Spanish Council for Scientific Research), Maria de Luna 10, 50018 Zaragoza (Spain); Remacha, Pilar; Ballester, Javier [LITEC-CSIC (Spanish Council for Scientific Research), Maria de Luna 10, 50018 Zaragoza (Spain); Fluid Mechanics Group, University of Zaragoza, Maria de Luna 3, 50018 Zaragoza (Spain); Ballesteros, Juan C.; Gimenez, Antonio [ENDESA GENERACION, S.A., Ribera del Loira 60, 28042 Madrid (Spain)

    2008-03-15

    In this paper the results of a complete set of devolatilization and combustion experiments performed with pulverized ({proportional_to}500 {mu}m) biomass in an entrained flow reactor under realistic combustion conditions are presented. The data obtained are used to derive the kinetic parameters that best fit the observed behaviors, according to a simple model of particle combustion (one-step devolatilization, apparent oxidation kinetics, thermally thin particles). The model is found to adequately reproduce the experimental trends regarding both volatile release and char oxidation rates for the range of particle sizes and combustion conditions explored. The experimental and numerical procedures, similar to those recently proposed for the combustion of pulverized coal [J. Ballester, S. Jimenez, Combust. Flame 142 (2005) 210-222], have been designed to derive the parameters required for the analysis of biomass combustion in practical pulverized fuel configurations and allow a reliable characterization of any finely pulverized biomass. Additionally, the results of a limited study on the release rate of nitrogen from the biomass particle along combustion are shown. (author)

  13. Improving the behavior of concrete exposed to fire by using an air entraining agent (AEA: Assessment of spalling

    Directory of Open Access Journals (Sweden)

    D'Aloia L.

    2013-09-01

    Full Text Available Several concrete mixes have been designed to evaluate the influence of an air entraining agent (AEA on spalling. Tests have been performed under the ISO curve (occasionally under the HCinc curve on specimens of various sizes and shapes to assess spalling. Results were somehow erratic on the smallest specimens whereas the beneficial effect of the air-bubble network could be emphasized on slabs.

  14. Cortical entrainment to music and its modulation by expertise.

    Science.gov (United States)

    Doelling, Keith B; Poeppel, David

    2015-11-10

    Recent studies establish that cortical oscillations track naturalistic speech in a remarkably faithful way. Here, we test whether such neural activity, particularly low-frequency (music and whether experience modifies such a cortical phenomenon. Music of varying tempi was used to test entrainment at different rates. In three magnetoencephalography experiments, we recorded from nonmusicians, as well as musicians with varying years of experience. Recordings from nonmusicians demonstrate cortical entrainment that tracks musical stimuli over a typical range of tempi, but not at tempi below 1 note per second. Importantly, the observed entrainment correlates with performance on a concurrent pitch-related behavioral task. In contrast, the data from musicians show that entrainment is enhanced by years of musical training, at all presented tempi. This suggests a bidirectional relationship between behavior and cortical entrainment, a phenomenon that has not previously been reported. Additional analyses focus on responses in the beta range (∼15-30 Hz)-often linked to delta activity in the context of temporal predictions. Our findings provide evidence that the role of beta in temporal predictions scales to the complex hierarchical rhythms in natural music and enhances processing of musical content. This study builds on important findings on brainstem plasticity and represents a compelling demonstration that cortical neural entrainment is tightly coupled to both musical training and task performance, further supporting a role for cortical oscillatory activity in music perception and cognition.

  15. On the fluid mechanics of fires

    Energy Technology Data Exchange (ETDEWEB)

    TIESZEN,SHELDON R.

    2000-02-29

    Fluid mechanics research related to fire is reviewed with focus on canonical flows, multiphysics coupling aspects, experimental and numerical techniques. Fire is a low-speed, chemically-reacting, flow in which buoyancy plans an important role. Fire research has focused on two canonical flows, the reacting boundary-layer and the reacting free plume. There is rich, multi-lateral, bi-directional, coupling among fluid mechanics and scalar transport, combustion, and radiation. There is only a limited experimental fluid-mechanics database for fire due to measurement difficulties in the harsh environment, and the focus within the fire community on thermal/chemical consequences. Increasingly, computational fluid dynamics techniques are being used to provide engineering guidance on thermal/chemical consequences and to study fire phenomenology.

  16. Entrained Flow Reactor Study of KCl Capture by Solid Additives

    DEFF Research Database (Denmark)

    Wang, Guoliang; Jensen, Peter Arendt; Wu, Hao

    been proved to be very promising additives and havereceived extensive studies during the past decades. However, mostprevious studies were carried out in fixed-bed reactors where the reaction conditions are obviously different from that in suspension fired boilers.Detailed knowledge on the reaction...

  17. Influence of the fire location and the size of a compartment on the heat and smoke flow out of the compartment

    Science.gov (United States)

    Wegrzyński, Wojciech; Konecki, Marek

    2018-01-01

    This paper presents results of CFD and scale modelling of the flow of heat and smoke inside and outside of a compartment, in case of fire. Estimation of mass flow out of a compartment is critical, as it is the boundary condition in further considerations related to the exhaust of the smoke from a building - also in analysis related to the performance of natural ventilation in wind conditions. Both locations of the fire and the size of compartment were addressed as possible variables, which influence the mass and the temperature of smoke that leaves the room engulfed in fire. Results of the study show small to none influence of both size of the compartment and the location of the fire, on the mass flow of smoke exiting the room. On the same time, both of these parameters influence the temperature of the smoke - in larger compartments lower average temperatures of the smoke layer, but higher maximum values were observed. Results of this study may be useful also in the determination of the worst case scenarios for structural analysis, or in the investiga tion of the spread of fire through the compartment. Based on the results presented in this study, researchers can attribute an expert judgement choice of fire location, as a single scenario that is representative of a larger amount of probable scenarios.

  18. Modeling post-fire hydro-geomorphic recovery in the Waldo Canyon Fire

    Science.gov (United States)

    Kinoshita, Alicia; Nourbakhshbeidokhti, Samira; Chin, Anne

    2016-04-01

    Wildfire can have significant impacts on watershed hydrology and geomorphology by changing soil properties and removing vegetation, often increasing runoff and soil erosion and deposition, debris flows, and flooding. Watershed systems may take several years or longer to recover. During this time, post-fire channel changes have the potential to alter hydraulics that influence characteristics such as time of concentration and increase time to peak flow, flow capacity, and velocity. Using the case of the 2012 Waldo Canyon Fire in Colorado (USA), this research will leverage field-based surveys and terrestrial Light Detection and Ranging (LiDAR) data to parameterize KINEROS2 (KINematic runoff and EROSion), an event oriented, physically-based watershed runoff and erosion model. We will use the Automated Geospatial Watershed Assessment (AGWA) tool, which is a GIS-based hydrologic modeling tool that uses commonly available GIS data layers to parameterize, execute, and spatially visualize runoff and sediment yield for watersheds impacted by the Waldo Canyon Fire. Specifically, two models are developed, an unburned (Bear Creek) and burned (Williams) watershed. The models will simulate burn severity and treatment conditions. Field data will be used to validate the burned watersheds for pre- and post-fire changes in infiltration, runoff, peak flow, sediment yield, and sediment discharge. Spatial modeling will provide insight into post-fire patterns for varying treatment, burn severity, and climate scenarios. Results will also provide post-fire managers with improved hydro-geomorphic modeling and prediction tools for water resources management and mitigation efforts.

  19. Determination of thermal characteristics of combustion products of fire-tube heat generator with flow turbulator

    OpenAIRE

    Lukjanov Alexander V.; Ostapenko Dmitry V.; Basist Dmitry V.

    2014-01-01

    Boiler construction is one of the major industries of any state. The aim is to determine the effect of the turbulator on the intensity of heat transfer in the convective part of the fire-tube heat generator of domestic production. The improvement of convective heating surfaces is one of the ways to increase the energy efficiency of the fire-tube heat generator. Since model of the process of heat transfer of gas flow in the convective tubes is multifactorial and does not have clear analytical ...

  20. Two-phase flow through small branches in a horizontal pipe with stratified flow

    International Nuclear Information System (INIS)

    Smoglie, C.

    1984-12-01

    This report presents the description and results of experiments designed to determine the mass flow rate and quality through a small break at the bottom, the top or the side of a main pipe with stratified gas-liquid flow. If the interface level is far below (above) the branch, only single-phase gas (liquid) flow enters the branch. For smaller distances the interface is locally deformed because of the pressure decrease due to the fluid acceleration near the branch inlet (Bernoulli effect) and liquid (gas) can be entrained. This report contains photographs illustrating the flow phenomena as well as a general correlation to determine the beginning of entrainment. Results are presented on the branch mass flow rate and quality as a function of a normalized distance between the interface and the branch inlet. A model was developed which enables to predict the branch quality and mass flux. Results from air-water flow through horizontal branches, were extrapolated for steam water flow at high pressure with critical branch mass flux. (orig./HP) [de

  1. Tuning Neural Phase Entrainment to Speech.

    Science.gov (United States)

    Falk, Simone; Lanzilotti, Cosima; Schön, Daniele

    2017-08-01

    Musical rhythm positively impacts on subsequent speech processing. However, the neural mechanisms underlying this phenomenon are so far unclear. We investigated whether carryover effects from a preceding musical cue to a speech stimulus result from a continuation of neural phase entrainment to periodicities that are present in both music and speech. Participants listened and memorized French metrical sentences that contained (quasi-)periodic recurrences of accents and syllables. Speech stimuli were preceded by a rhythmically regular or irregular musical cue. Our results show that the presence of a regular cue modulates neural response as estimated by EEG power spectral density, intertrial coherence, and source analyses at critical frequencies during speech processing compared with the irregular condition. Importantly, intertrial coherences for regular cues were indicative of the participants' success in memorizing the subsequent speech stimuli. These findings underscore the highly adaptive nature of neural phase entrainment across fundamentally different auditory stimuli. They also support current models of neural phase entrainment as a tool of predictive timing and attentional selection across cognitive domains.

  2. Water Entrainment in Concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben

    This report gives a survey of different techniques for incorporation of designed, water-filled cavities in concrete: Water entrainment. Also an estimate of the optimum size of the water inclusions is given. Water entrainment can be used to avoid self-desiccation and self-desiccation shrinkage...... during hydration [1,26]. What is needed is some sort of container which retains the shape of the water when mixed into the concrete. The container may function based on several different physical or chemical principles. Cells and gels are examples of containers found in nature. A cell membrane provides...... a boundary to water, whereas a polymer network incorporates water in its intersticious space with its affinity due to interaction energy and polymer entropy. Such containers allow water to be stored as an entity. In relation to concrete the water encapsulation may be accomplished either before or after start...

  3. The Role of Oscillatory Phase in Determining the Temporal Organization of Perception: Evidence from Sensory Entrainment.

    Science.gov (United States)

    Ronconi, Luca; Melcher, David

    2017-11-01

    Recent behavioral, neuroimaging, and neurophysiological studies have renewed the idea that the information processing within different temporal windows is linked to the phase and/or frequency of the ongoing oscillations, predominantly in the theta/alpha band (∼4-7 and 8-12 Hz, respectively). However, being correlational in nature, this evidence might reflect a nonfunctional byproduct rather than having a causal role. A more direct link can be shown with methods that manipulate oscillatory activity. Here, we used audiovisual entrainment at different frequencies in the prestimulus period of a temporal integration/segregation task. We hypothesized that entrainment would align ongoing oscillations and drive them toward the stimulation frequency. To reveal behavioral oscillations in temporal perception after the entrainment, we sampled the segregation/integration performance densely in time. In Experiment 1, two groups of human participants (both males and females) received stimulation either at the lower or the upper boundary of the alpha band (∼8.5 vs 11.5 Hz). For both entrainment frequencies, we found a phase alignment of the perceptual oscillation across subjects, but with two different power spectra that peaked near the entrainment frequency. These results were confirmed when perceptual oscillations were characterized in the time domain with sinusoidal fittings. In Experiment 2, we replicated the findings in a within-subject design, extending the results for frequencies in the theta (∼6.5 Hz), but not in the beta (∼15 Hz), range. Overall, these findings show that temporal segregation can be modified by sensory entrainment, providing evidence for a critical role of ongoing oscillations in the temporal organization of perception. SIGNIFICANCE STATEMENT The continuous flow of sensory input is not processed in an analog fashion, but rather is grouped by the perceptual system over time. Recent studies pinpointed the phase and/or frequency of the neural

  4. A Population of Indirect Pathway Striatal Projection Neurons Is Selectively Entrained to Parkinsonian Beta Oscillations.

    Science.gov (United States)

    Sharott, Andrew; Vinciati, Federica; Nakamura, Kouichi C; Magill, Peter J

    2017-10-11

    Classical schemes of basal ganglia organization posit that parkinsonian movement difficulties presenting after striatal dopamine depletion stem from the disproportionate firing rates of spiny projection neurons (SPNs) therein. There remains, however, a pressing need to elucidate striatal SPN firing in the context of the synchronized network oscillations that are abnormally exaggerated in cortical-basal ganglia circuits in parkinsonism. To address this, we recorded unit activities in the dorsal striatum of dopamine-intact and dopamine-depleted rats during two brain states, respectively defined by cortical slow-wave activity (SWA) and activation. Dopamine depletion escalated striatal net output but had contrasting effects on "direct pathway" SPNs (dSPNs) and "indirect pathway" SPNs (iSPNs); their firing rates became imbalanced, and they disparately engaged in network oscillations. Disturbed striatal activity dynamics relating to the slow (∼1 Hz) oscillations prevalent during SWA partly generalized to the exaggerated beta-frequency (15-30 Hz) oscillations arising during cortical activation. In both cases, SPNs exhibited higher incidences of phase-locked firing to ongoing cortical oscillations, and SPN ensembles showed higher levels of rhythmic correlated firing, after dopamine depletion. Importantly, in dopamine-depleted striatum, a widespread population of iSPNs, which often displayed excessive firing rates and aberrant phase-locked firing to cortical beta oscillations, preferentially and excessively synchronized their firing at beta frequencies. Conversely, dSPNs were neither hyperactive nor synchronized to a large extent during cortical activation. These data collectively demonstrate a cell type-selective entrainment of SPN firing to parkinsonian beta oscillations. We conclude that a population of overactive, excessively synchronized iSPNs could orchestrate these pathological rhythms in basal ganglia circuits. SIGNIFICANCE STATEMENT Chronic depletion of dopamine

  5. Mixing of high density solution in vertical upward flow

    International Nuclear Information System (INIS)

    Kumamaru, Hiroshige; Hosogi, Nobuyoshi; Komada, Toshiaki; Fujiwara, Yoshiki

    1999-01-01

    Experimental and analytical studies have been performed in order to provide fundamental data and a numerical calculation model on the mixing of boric acid solution, injected from the standby liquid control system (SLCS), under a low natural circulation flow during an ATWS in a BWR. First, fundamental experiments on the mixing of high-density solution in vertically-upward water flow have been performed by using a small apparatus. Mixing patterns observed in the experiments have been classified to two groups, i.e. complete mixing (entrainment) and incomplete mixing (entrainment). In the complete mixing, the injected high-density solution is mixed (entrained) completely into the vertically-upward water flow. From the experiments, the minimum water flow rates in which the complete mixing (entrainment) is achieved have been obtained for various solution densities and solution injection rates. Secondly, two-dimensional numerical calculations have been performed. A continuity equation for total fluid, momentum equations in two directions and a continuity equation for solute are solved by using the finite difference method for discretization method and by following the MAC method for solution procedure. The calculations have predicted nearly the minimum water flow rate in which the complete mixing is achieved, while the calculations have been performed only for one combination of the solution density and solution injection rate until now. (author)

  6. Sensory Entrainment Mechanisms in Auditory Perception: Neural Synchronization Cortico-Striatal Activation.

    Science.gov (United States)

    Sameiro-Barbosa, Catia M; Geiser, Eveline

    2016-01-01

    The auditory system displays modulations in sensitivity that can align with the temporal structure of the acoustic environment. This sensory entrainment can facilitate sensory perception and is particularly relevant for audition. Systems neuroscience is slowly uncovering the neural mechanisms underlying the behaviorally observed sensory entrainment effects in the human sensory system. The present article summarizes the prominent behavioral effects of sensory entrainment and reviews our current understanding of the neural basis of sensory entrainment, such as synchronized neural oscillations, and potentially, neural activation in the cortico-striatal system.

  7. Sensory Entrainment Mechanisms in Auditory Perception: Neural Synchronization Cortico-Striatal Activation

    Science.gov (United States)

    Sameiro-Barbosa, Catia M.; Geiser, Eveline

    2016-01-01

    The auditory system displays modulations in sensitivity that can align with the temporal structure of the acoustic environment. This sensory entrainment can facilitate sensory perception and is particularly relevant for audition. Systems neuroscience is slowly uncovering the neural mechanisms underlying the behaviorally observed sensory entrainment effects in the human sensory system. The present article summarizes the prominent behavioral effects of sensory entrainment and reviews our current understanding of the neural basis of sensory entrainment, such as synchronized neural oscillations, and potentially, neural activation in the cortico-striatal system. PMID:27559306

  8. The effects of a flow obstacle on liquid film flowing concurrently with air in a horizontal rectangular duct

    International Nuclear Information System (INIS)

    Fukano, Tohru; Tominaga, Akira; Morikawa, Kengo.

    1986-01-01

    The aspect of a liquid film flowing near a flat plate type obstacle was observed, and the liquid film thickness and the entrainment were measured under a wide range of gas and liquid flow rates. The results are summarized as follows: (1) The configurations of film flows near the obstacle are classified according to whether (a) the liquid film climbs over the obstacle or not, (b) the air flows under the obstacle or not, or (c) the liquid film swells or sinks just upstream or downstream of the obstacle. (2) The lower the liquid flow rate, the larger the effect of the obstacle on the film thickness. (3) The generation of entrainment is regulated by the obstacle when the air volumetric flux is high and by the disturbance wave when it is low. (author)

  9. Gasification of peat and biomass in suspension flow 2; Turpeen ja biomassan suspensiokaasutus 2

    Energy Technology Data Exchange (ETDEWEB)

    Kurkela, E.; Hepola, J. [VTT Energy, Espoo (Finland); Haukka, P.; Vehmaan-Kreula, M.; Raiko, R. [Tampere Univ. of Technology (Finland)

    1996-12-01

    This project was an extension of the earlier Liekki-project 402 carried out in 1993-1994. The aims of the 1995 project were: (1) to study the formation of problematic tar/soot compounds and nitrogen pounds in the conditions of entrained flow gasification of biomass and peat, (2) study the product yields and kinetics of pyrolysis, and (3) to develop simulation methods for entrained flow pyrolysis and gasification. Pyrolysis and gasification tests were carried out at a new entrained flow reactor of the Gasification Research Group of VTT using mainly peat as the feedstock. The pyrolysis kinetics was studies using three particle size distributions of fuel peat (0.075-0.125 mm, 0.16-0.25 mm and 0.315-0.5 mm). The char yields were determined at two temperatures (900 and 1000 deg C) and the effects fuel to gas ratio (suspension density) as well as the effects of gas atmosphere were determined. Limited amount of tests were also carried out with pine wood and dried de-inking sludge. The formation of tars and nitrogen compounds was studied with peat as the feedstock. Based on the test results of this project and the on earlier fluidized-bed gasification data of VTT, the following conclusions can be made: (1) the char yields in rapid entrained flow pyrolysis of small particles of peat and biomass are considerably lower than derived in fluid-bed pyrolysis of more coarse feedstocks. Consequently, simple entrained flow reactors without any recycling of char could already give rather high carbon conversions. However, high carbon conversions can also be easily achieved in fluidized-bed gasifiers with biomass fuels due to the high gasification reactivity of the char, (2) more tars were formed in entrained flow pyrolysis of peat than in fluidized-bed experiments carried out at the same temperature, (3) the total conversion of peat nitrogen to NH{sub 3}+HCN was as high in the entrained flow pyrolysis as in the fluid-bed pyrolysis experiments. (Abstract Truncated)

  10. Numerical investigation on the gas entrainment rate on ventilated supercavity body

    Directory of Open Access Journals (Sweden)

    WuGang Yang

    2016-12-01

    Full Text Available The supercavitation technique provides a means of significantly increasing the velocity of an underwater vehicle. This technique involves essentially the creation of stable supercavity shape. The method of artificial ventilation is most effective for generating and dominating the supercavity. This paper focuses on the numerical simulation of flow field around three-dimensional body. The method is based on the multiphase computational fluid dynamics model combined with the turbulence model and the full cavity model. The fundamental similarity parameters of ventilated supercavity flows that include cavitation number, Froude number Fr, entrainment rate CQ, and drag coefficient Cx are all investigated numerically in the case of steady flow and gravity field. We discuss the following simulations results in three parts: (1 the variations of the cavitation number and the supercavity’s relative diameter with entrainment rate; (2 the drag coefficient versus the cavitation number; and (3 deformation of supercavity axis caused by gravitational effect for three different fixed three Froude numbers. In the full paper, we give the comparison results of the drag reduction ratio among numerical simulation and experiment conducted in hydrodynamic tunnel and towing tank, respectively. We summarize our discussion of gravitational effect on the axis deformation of supercavity as follows: in the case of smaller Froude number, the inclination of the cavity axis increases monotonously with increasing horizontal length and reaches its maximal value at the end of supercavity; this deformation can be almost completely negligible when the Froude number Fr is larger than 7.0. The comparisons with the experimental data in the hydrodynamic tunnel and the towing tank indicate that the present method is effective for predicting the flows around ventilated supercavity; that the numerical results is in good agreement with the experimental ones and that the maximal value of the

  11. Motion of water droplets in the counter flow of high-temperature combustion products

    Science.gov (United States)

    Volkov, R. S.; Strizhak, P. A.

    2018-01-01

    This paper presents the experimental studies of the deceleration, reversal, and entrainment of water droplets sprayed in counter current flow to a rising stream of high-temperature (1100 K) combustion gases. The initial droplets velocities 0.5-2.5 m/s, radii 10-230 μm, relative volume concentrations 0.2·10-4-1.8·10-4 (m3 of water)/(m3 of gas) vary in the ranges corresponding to promising high-temperature (over 1000 K) gas-vapor-droplet applications (for example, polydisperse fire extinguishing using water mist, fog, or appropriate water vapor-droplet veils, thermal or flame treatment of liquids in the flow of combustion products or high-temperature air; creating coolants based on flue gas, vapor and water droplets; unfreezing of granular media and processing of the drossed surfaces of thermal-power equipment; ignition of liquid and slurry fuel droplets). A hardware-software cross-correlation complex, high-speed (up to 105 fps) video recording tools, panoramic optical techniques (Particle Image Velocimetry, Particle Tracking Velocimetry, Interferometric Particle Imagine, Shadow Photography), and the Tema Automotive software with the function of continuous monitoring have been applied to examine the characteristics of the processes under study. The scale of the influence of initial droplets concentration in the gas flow on the conditions and features of their entrainment by high-temperature gases has been specified. The dependencies Red = f(Reg) and Red' = f(Reg) have been obtained to predict the characteristics of the deceleration of droplets by gases at different droplets concentrations.

  12. Doing Duo – a Case Study of Entrainment in William Forsythe’s Choreography Duo

    Directory of Open Access Journals (Sweden)

    Elizabeth eWaterhouse

    2014-10-01

    Full Text Available Entrainment theory focuses on processes in which interacting (i.e. coupled rhythmic systems stabilize, producing synchronization in the ideal sense, and forms of phase related rhythmic coordination in complex cases. In human action, entrainment involves spatiotemporal and social aspects, characterizing the meaningful activities of music, dance, and communication. How can the phenomenon of human entrainment be meaningfully studied in complex situations such as dance? We present an in-progress case study of entrainment in William Forsythe's choreography Duo, a duet in which coordinated rhythmic activity is achieved without an external musical beat and without touch-based interaction. Using concepts of entrainment from different disciplines as well as insight from Duo performer Riley Watts, we question definitions of entrainment in the context of dance. The functions of chorusing, turn-taking, complementary action, cues and alignments are discussed and linked to supporting annotated video material. While Duo challenges the definition of entrainment in dance as coordinated response to an external musical or rhythmic signal, it supports the definition of entrainment as coordinated interplay of motion and sound production by active agents (i.e., dancers in the field. Agreeing that human entrainment should be studied on multiple levels, we suggest that entrainment between the dancers in Duo is elastic in time and a propose how to test this hypothesis empirically. We do not claim that our proposed model of elasticity is applicable to all forms of human entrainment nor to all to examples of entrainment in dance. Rather, we suggest studying higher order phase correction (the stabilizing tendency of entrainment as a potential aspect to be incorporated into other models.

  13. Behaviour of heavy metals during the thermal conversion of sawdust in an entrained flow reactor

    Energy Technology Data Exchange (ETDEWEB)

    Klensch, S.; Reimert, R. [Engler-Bunte-Inst., Bereich Gas, Erdoel und Kohle, Univ. Karlsruhe, Karlsruhe (Germany)

    1999-07-01

    Since its utilization is nearly CO{sub 2}-neutral, biomass represents a major alternative energy carrier in comparison with fossil fuels in CO{sub 2} reduction scenarios frequently discussed. Decentral generation of power and heat in medium sized plants could develop as a preferred application in future. During thermal conversion (gasification and combustion) of biomass the inorganic matter including the heavy metals will be found in the solid residues, i. e. slags and ashes, and in very low concentrations in the product gas (fuel or flue gas). The ashes should be returned to the forests and the agricultural areas respectively to avoid the use of industrial fertilizers. However, for this purpose the heavy metal concentrations of ashes may not exceed specific limit values, otherwise the returned ashes can lead to harmful effects on the ecological system. In awareness of this problem, in Austria some limit values for the concentrations of Cd, Cr, Cu, Ni, Pb and Zn in returned ashes are valid since 1997. No danger for the environment can be expected by slags containing heavy metals. The heavy metals are fixed environmentally neutral in the glass matrix as has been proven for coal and for residue gasification many times. Dividing the total of the residues into such two streams (returned ash and slag) avoids the disposal of the ashes. The heavy metal behaviour during the thermal conversion of sawdust was investigated in a bench scale plant. In essence, the plant consists of an entrained flow reactor (length of reaction zone: 2,500 mm; inner diameter: 70 mm) and a candle barrier filter with 6 rigid ceramic filter elements (DIA-Schumalith 10-20). The biomass flow rate is as high as 6 kg/h and the operating pressure is about 0.12 MPa. Experimental results show the influences of the conversion temperature (1100 - 1300 C), of the dedusting temperature (350 - 800 C), and of the gas atmosphere (reducing, oxidising) on the heavy metal concentrations of the slag and of the fly

  14. Evaluation of ash deposits during experimental investigation of co-firing of Bosnian coal with wooden biomass

    Energy Technology Data Exchange (ETDEWEB)

    Smajevic, Izet; Kazagic, Anes [JP Elektroprivreda BiH d.d., Sarajevo (Bosnia and Herzegovina); Sarajevo Univ. (Bosnia and Herzegovina). Faculty of Mechanical Engineering

    2008-07-01

    The paper is addressed to the development and use different criteria for evaluation of ash deposits collected during experimental co-firing of Bosnian coals with wooden biomass. Spruce saw dust was used for the co-firing tests with the Kakanj brown coal and with a lignite blend consisted of the Dubrave lignite and the Sikulje lignite. The coal/biomass mixtures at 93:7 %w and at 80:20 %w were tested. Experimental lab-scale facility PF entrained flow reactor is used for the co-firing tests. The reactor allows examination of fouling/slagging behaviors and emissions at various and infinitely variable process temperature which can be set at will in the range from ambient to 1560 C. Ash deposits are collected on two non-cooled ceramic probes and one water-cooled metal surface. Six different criteria are developed and used to evaluate behavior of the ash deposits on the probes: ash deposit shape, state and structure, which are analyzed visually - photographically and optically by a microscope, rate of adhesion and ash deposit strength, analyzed by physic acting to the ash deposits, and finally deposition rate, determined as a mass of the deposit divided by the collecting area and the time of collecting. Furthermore, chemical composition analysis and AFT of the ash deposits were also done to provide additional information on the deposits. (orig.)

  15. Two-phase flow through small branches in a horizontal pipe with stratified flow

    International Nuclear Information System (INIS)

    Smoglie, C.

    1985-02-01

    In the field of reactor safety the occurrence of a small break in a horizontal primary coolant pipe is of great importance. This report presents the description and results of experiments designed to determine the mass flow rate and quality through a small break at the bottom, the top or the side of a main pipe with stratified gas-liquid flow. If the interface level is far below (above) the branch, only single-phase gas (liquid) flow enters the branch. For smaller distances the interface is locally deformed because of the pressure decrease due to the fluid acceleration near the branch inlet (Bernoulli effect) and liquid (gas) can be entrained. This report contains photographs illustrating the flow phenomena as well as a general correlation to determine the beginning of entrainment. Results are presented on the branch mass flow rate and quality as a function of a normalized distance between the interface and the branch inlet. A model was developed which enables to predict the branch quality and mass flux. Results from air-water flow through horizontal branches, were extrapolated for steam water flow at high pressure with critical branch mass flux. (orig./HS) [de

  16. Entrainment of Spontaneously Hypertensive Rat Fibroblasts by Temperature Cycles

    Science.gov (United States)

    Sládek, Martin; Sumová, Alena

    2013-01-01

    The functional state of the circadian system of spontaneously hypertensive rats (SHR) differs in several characteristics from the functional state of normotensive Wistar rats. Some of these changes might be due to the compromised ability of the central pacemaker to entrain the peripheral clocks. Daily body temperature cycles represent one of the important cues responsible for the integrity of the circadian system, because these cycles are driven by the central pacemaker and are able to entrain the peripheral clocks. This study tested the hypothesis that the aberrant peripheral clock entrainment of SHR results from a compromised peripheral clock sensitivity to the daily temperature cycle resetting. Using cultured Wistar rat and SHR fibroblasts transfected with the circadian luminescence reporter Bmal1-dLuc, we demonstrated that two consecutive square-wave temperature cycles with amplitudes of 2.5°C are necessary and sufficient to restart the dampened oscillations and entrain the circadian clocks in both Wistar rat and SHR fibroblasts. We also generated a phase response curve to temperature cycles for fibroblasts of both rat strains. Although some of the data suggested a slight resistance of SHR fibroblasts to temperature entrainment, we concluded that the overall effect it too weak to be responsible for the differences between the SHR and Wistar in vivo circadian phenotype. PMID:24116198

  17. Modelling turbulent fluid flows in nuclear and fossil-fired power plants

    International Nuclear Information System (INIS)

    Viollet, P.L.

    1995-06-01

    The turbulent flows encountered in nuclear reactor thermal hydraulic studies or fossil-fired plant thermo-aerodynamic analyses feature widely varying characteristics, frequently entailing heat transfers and two-phase flows so that modelling these phenomena tends more and more to involve coupling between several branches of engineering. Multi-scale geometries are often encountered, with complex wall shapes, such as a PWR vessel, a reactor coolant pump impeller or a circulating fluidized bed combustion chamber. When it comes to validating physical models of these flows, the analytical process highlights the main descriptive parameters of local flow conditions: tensor characterizing the turbulence anisotropy, characteristic time scales for turbulent flow particle dynamics. Cooperative procedures implemented between national or international working parties can accelerate validation by sharing and exchanging results obtained by the various organizations involved. With this principle accepted, we still have to validate the products themselves, i.e. the software used for the studies. In this context, the ESTET, ASTRID and N3S codes have been subjected to a battery of test cases covering their respective fields of application. These test cases are re-run for each new version, so that the sets of test cases systematically benefit from the gradually upgraded functionalities of the codes. (author). refs., 3 figs., 6 tabs

  18. The performative pleasure of imprecision: a diachronic study of entrainment in music performance

    Directory of Open Access Journals (Sweden)

    Andrew eGeeves

    2014-10-01

    Full Text Available This study focuses in on a moment of live performance in which the entrainment amongst a musical quartet is threatened. Entrainment is asymmetric in so far as there is an ensemble leader who improvises and expands the structure of a last chorus of a piece of music beyond the limits tacitly negotiated during prior rehearsals and performances. Despite the risk of entrainment being disturbed and performance interrupted, the other three musicians in the quartet follow the leading performer and smoothly transition into unprecedented performance territory. We use this moment of live performance to work back through the fieldwork data, building a diachronic study of the development and bases of entrainment in live music performance. We introduce the concept of entrainment and profile previous theory and research relevant to entrainment in music performance. After outlining our methodology, we trace the evolution of the structure of the piece of music from first rehearsal to final performance. Using video clip analysis, interviews and field notes we consider how entrainment shaped and was shaped by the moment of performance in focus. The sense of trust between quartet musicians is established through entrainment processes, is consolidated via smooth adaptation to the threats of disruption. Nonverbal communicative exchanges, via eye contact, gesture and spatial proximity, sustain entrainment through phase shifts occurring swiftly and on the fly in performance contexts. These exchanges permit smooth adaptation promoting trust. This frees the quartet members to play with the potential disturbance of equilibrium inherent in entrained relationships and to play with this tension in an improvisatory way that enhances audience engagement and the live quality of performance.

  19. Mitigating operating room fires: development of a carbon dioxide fire prevention device.

    Science.gov (United States)

    Culp, William C; Kimbrough, Bradly A; Luna, Sarah; Maguddayao, Aris J

    2014-04-01

    Operating room fires are sentinel events that present a real danger to surgical patients and occur at least as frequently as wrong-sided surgery. For fire to occur, the 3 points of the fire triad must be present: an oxidizer, an ignition source, and fuel source. The electrosurgical unit (ESU) pencil triggers most operating room fires. Carbon dioxide (CO2) is a gas that prevents ignition and suppresses fire by displacing oxygen. We hypothesize that a device can be created to reduce operating room fires by generating a cone of CO2 around the ESU pencil tip. One such device was created by fabricating a divergent nozzle and connecting it to a CO2 source. This device was then placed over the ESU pencil, allowing the tip to be encased in a cone of CO2 gas. The device was then tested in 21%, 50%, and 100% oxygen environments. The ESU was activated at 50 W cut mode while placing the ESU pencil tip on a laparotomy sponge resting on an aluminum test plate for up to 30 seconds or until the sponge ignited. High-speed videography was used to identify time of ignition. Each test was performed in each oxygen environment 5 times with the device activated (CO2 flow 8 L/min) and with the device deactivated (no CO2 flow-control). In addition, 3-dimensional spatial mapping of CO2 concentrations was performed with a CO2 sampling device. The median ± SD [range] ignition time of the control group in 21% oxygen was 2.9 s ± 0.44 [2.3-3.0], in 50% oxygen 0.58 s ± 0.12 [0.47-0.73], and in 100% oxygen 0.48 s ± 0.50 [0.03-1.27]. Fires were ignited with each control trial (15/15); no fires ignited when the device was used (0/15, P fire prevention device can be created by using a divergent nozzle design through which CO2 passes, creating a cone of fire suppressant. This device as demonstrated in a flammability model effectively reduced the risk of fire. CO2 3-dimensional spatial mapping suggests effective fire reduction at least 1 cm away from the tip of the ESU pencil at 8 L/min CO2 flow

  20. Microparticle Flow Sensor

    Science.gov (United States)

    Morrison, Dennis R.

    2005-01-01

    The microparticle flow sensor (MFS) is a system for identifying and counting microscopic particles entrained in a flowing liquid. The MFS includes a transparent, optoelectronically instrumented laminar-flow chamber (see figure) and a computer for processing instrument-readout data. The MFS could be used to count microparticles (including micro-organisms) in diverse applications -- for example, production of microcapsules, treatment of wastewater, pumping of industrial chemicals, and identification of ownership of liquid products.

  1. Study on the effect of free acidity and entrained TBP in UNPS on the quality of ADU powder

    International Nuclear Information System (INIS)

    Prudhvi Raju, P.V.S.N.; Mandal, D.

    2015-01-01

    Graphical abstract: From the experimental study it was found that mean particle size of precipitated Ammonium Di-Uranate (ADU) depends on the free acidity content and entrained TBP in Uranyl Nitrate Pure Solution (UNPS). It was found that as the free acidity as well as the entrained TBP content in UNPS increases, mean particle size of precipitated ADU decreases. Based on the experimental results two correlations were developed as shown in below figures. - Highlights: • The mean particle size of precipitated ADU depends on the free acidity in UNPS. • The mean particle size of precipitated ADU also depends on the entrained TBP in UNPS. • As free acidity in UNPS increases, mean particle size of precipitated ADU decreases. • As entrained TBP in UNPS increases, particle size of precipitated ADU decreases. • Based on the experimental results two correlations were developed to find d p of ADU. - Abstract: The mean particle size and size distribution of Ammonium Di-Uranate (ADU) particles, precipitated during the precipitation reaction of Uranyl Nitrate Pure Solution (UNPS) with ammonia play an important role on the sintered density of UO 2 pellets. The quality of precipitated ADU depends on number of process parameters viz., pH of UNPS, concentration of uranium in UNPS, flow rate of ammonium hydroxide, temperature etc. However, the effects of the presence of free acid and entrained Tri-Butyl-Phosphate (TBP) in UNPS on the quality of ADU powder were not studied till date. Experiments were conducted to study the effect of free acidity and the presence of entrained TBP on the quality of precipitated ADU particles. It was found that as the concentration of free acid as well as the concentration of entrained TBP in UNPS increases, the particle size of precipitated ADU decreases. Based on the experimental results two correlations were developed to determine the mean particle size of ADU; one is based on the free acid content of UNPS and the other is based on the

  2. Study on the effect of free acidity and entrained TBP in UNPS on the quality of ADU powder

    Energy Technology Data Exchange (ETDEWEB)

    Prudhvi Raju, P.V.S.N. [Nuclear Fuel Complex, Hyderabad 500 062 (India); Mandal, D., E-mail: dmandal@barc.gov.in [Chemical Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2015-09-15

    Graphical abstract: From the experimental study it was found that mean particle size of precipitated Ammonium Di-Uranate (ADU) depends on the free acidity content and entrained TBP in Uranyl Nitrate Pure Solution (UNPS). It was found that as the free acidity as well as the entrained TBP content in UNPS increases, mean particle size of precipitated ADU decreases. Based on the experimental results two correlations were developed as shown in below figures. - Highlights: • The mean particle size of precipitated ADU depends on the free acidity in UNPS. • The mean particle size of precipitated ADU also depends on the entrained TBP in UNPS. • As free acidity in UNPS increases, mean particle size of precipitated ADU decreases. • As entrained TBP in UNPS increases, particle size of precipitated ADU decreases. • Based on the experimental results two correlations were developed to find d{sub p} of ADU. - Abstract: The mean particle size and size distribution of Ammonium Di-Uranate (ADU) particles, precipitated during the precipitation reaction of Uranyl Nitrate Pure Solution (UNPS) with ammonia play an important role on the sintered density of UO{sub 2} pellets. The quality of precipitated ADU depends on number of process parameters viz., pH of UNPS, concentration of uranium in UNPS, flow rate of ammonium hydroxide, temperature etc. However, the effects of the presence of free acid and entrained Tri-Butyl-Phosphate (TBP) in UNPS on the quality of ADU powder were not studied till date. Experiments were conducted to study the effect of free acidity and the presence of entrained TBP on the quality of precipitated ADU particles. It was found that as the concentration of free acid as well as the concentration of entrained TBP in UNPS increases, the particle size of precipitated ADU decreases. Based on the experimental results two correlations were developed to determine the mean particle size of ADU; one is based on the free acid content of UNPS and the other is based on

  3. Impact of Air Entraining Method on the Resistance of Concrete to Internal Cracking

    Science.gov (United States)

    Wawrzeńczyk, Jerzy; Molendowska, Agnieszka

    2017-10-01

    This paper presents the test results of air entrained concrete mixtures made at a constant W/C ratio of 0.44. Three different air entraining agents were used: polymer microspheres, glass microspheres and a conventional air entraining admixture. The aim of this study was to compare the effectiveness of the air entraining methods. Concrete mixture tests were performed for consistency (slump test), density and, in the case of AEA series, air content by pressure method. Hardened concrete tests were performed for compressive strength, water absorption, resistance to chloride ingress, and freeze-thaw durability - resistance to internal cracking tests were conducted in accordance with PN-88/B-06250 on cube specimens and with the modified ASTM C666 A test method on beam specimens; porosity characteristics (A, A300, \\bar L) were determined to PN-EN 480-11:1998. No significant mass and length changes were recorded for the concrete air entrained with the conventional methods or with polymer microspheres. The results indicate that polymer microspheres are a very good alternative to traditional air entraining methods for concrete, providing effective air entrainment and protection from freezing and thawing. The glass microsphere-based concretes showed insufficient freeze-thaw resistance. The test results indicate that both the conventional methods (AEA) and the air entrainment by polymer microspheres are effective air entraining methods. It has to be noted that in the case of the use of polymer microspheres, a comparable value of \\bar L and a very good freeze-thaw resistance can be achieved at a noticeably lower air and micropore contents and at lower strength loss.

  4. Estimated probability of postwildfire debris flows in the 2012 Whitewater-Baldy Fire burn area, southwestern New Mexico

    Science.gov (United States)

    Tillery, Anne C.; Matherne, Anne Marie; Verdin, Kristine L.

    2012-01-01

    In May and June 2012, the Whitewater-Baldy Fire burned approximately 1,200 square kilometers (300,000 acres) of the Gila National Forest, in southwestern New Mexico. The burned landscape is now at risk of damage from postwildfire erosion, such as that caused by debris flows and flash floods. This report presents a preliminary hazard assessment of the debris-flow potential from 128 basins burned by the Whitewater-Baldy Fire. A pair of empirical hazard-assessment models developed by using data from recently burned basins throughout the intermountain Western United States was used to estimate the probability of debris-flow occurrence and volume of debris flows along the burned area drainage network and for selected drainage basins within the burned area. The models incorporate measures of areal burned extent and severity, topography, soils, and storm rainfall intensity to estimate the probability and volume of debris flows following the fire. In response to the 2-year-recurrence, 30-minute-duration rainfall, modeling indicated that four basins have high probabilities of debris-flow occurrence (greater than or equal to 80 percent). For the 10-year-recurrence, 30-minute-duration rainfall, an additional 14 basins are included, and for the 25-year-recurrence, 30-minute-duration rainfall, an additional eight basins, 20 percent of the total, have high probabilities of debris-flow occurrence. In addition, probability analysis along the stream segments can identify specific reaches of greatest concern for debris flows within a basin. Basins with a high probability of debris-flow occurrence were concentrated in the west and central parts of the burned area, including tributaries to Whitewater Creek, Mineral Creek, and Willow Creek. Estimated debris-flow volumes ranged from about 3,000-4,000 cubic meters (m3) to greater than 500,000 m3 for all design storms modeled. Drainage basins with estimated volumes greater than 500,000 m3 included tributaries to Whitewater Creek, Willow

  5. Speech Rate Entrainment in Children and Adults With and Without Autism Spectrum Disorder.

    Science.gov (United States)

    Wynn, Camille J; Borrie, Stephanie A; Sellers, Tyra P

    2018-05-03

    Conversational entrainment, a phenomenon whereby people modify their behaviors to match their communication partner, has been evidenced as critical to successful conversation. It is plausible that deficits in entrainment contribute to the conversational breakdowns and social difficulties exhibited by people with autism spectrum disorder (ASD). This study examined speech rate entrainment in children and adult populations with and without ASD. Sixty participants including typically developing children, children with ASD, typically developed adults, and adults with ASD participated in a quasi-conversational paradigm with a pseudoconfederate. The confederate's speech rate was digitally manipulated to create slow and fast speech rate conditions. Typically developed adults entrained their speech rate in the quasi-conversational paradigm, using a faster rate during the fast speech rate conditions and a slower rate during the slow speech rate conditions. This entrainment pattern was not evident in adults with ASD or in children populations. Findings suggest that speech rate entrainment is a developmentally acquired skill and offers preliminary evidence of speech rate entrainment deficits in adults with ASD. Impairments in this area may contribute to the conversational breakdowns and social difficulties experienced by this population. Future work is needed to advance this area of inquiry.

  6. Large-scale pool fires

    Directory of Open Access Journals (Sweden)

    Steinhaus Thomas

    2007-01-01

    Full Text Available A review of research into the burning behavior of large pool fires and fuel spill fires is presented. The features which distinguish such fires from smaller pool fires are mainly associated with the fire dynamics at low source Froude numbers and the radiative interaction with the fire source. In hydrocarbon fires, higher soot levels at increased diameters result in radiation blockage effects around the perimeter of large fire plumes; this yields lower emissive powers and a drastic reduction in the radiative loss fraction; whilst there are simplifying factors with these phenomena, arising from the fact that soot yield can saturate, there are other complications deriving from the intermittency of the behavior, with luminous regions of efficient combustion appearing randomly in the outer surface of the fire according the turbulent fluctuations in the fire plume. Knowledge of the fluid flow instabilities, which lead to the formation of large eddies, is also key to understanding the behavior of large-scale fires. Here modeling tools can be effectively exploited in order to investigate the fluid flow phenomena, including RANS- and LES-based computational fluid dynamics codes. The latter are well-suited to representation of the turbulent motions, but a number of challenges remain with their practical application. Massively-parallel computational resources are likely to be necessary in order to be able to adequately address the complex coupled phenomena to the level of detail that is necessary.

  7. Post-fire debris-flow hazard assessment of the area burned by the 2013 Beaver Creek Fire near Hailey, central Idaho

    Science.gov (United States)

    Skinner, Kenneth D.

    2013-01-01

    A preliminary hazard assessment was developed for debris-flow hazards in the 465 square-kilometer (115,000 acres) area burned by the 2013 Beaver Creek fire near Hailey in central Idaho. The burn area covers all or part of six watersheds and selected basins draining to the Big Wood River and is at risk of substantial post-fire erosion, such as that caused by debris flows. Empirical models derived from statistical evaluation of data collected from recently burned basins throughout the Intermountain Region in Western United States were used to estimate the probability of debris-flow occurrence, potential volume of debris flows, and the combined debris-flow hazard ranking along the drainage network within the burn area and to estimate the same for analyzed drainage basins within the burn area. Input data for the empirical models included topographic parameters, soil characteristics, burn severity, and rainfall totals and intensities for a (1) 2-year-recurrence, 1-hour-duration rainfall, referred to as a 2-year storm (13 mm); (2) 10-year-recurrence, 1-hour-duration rainfall, referred to as a 10-year storm (19 mm); and (3) 25-year-recurrence, 1-hour-duration rainfall, referred to as a 25-year storm (22 mm). Estimated debris-flow probabilities for drainage basins upstream of 130 selected basin outlets ranged from less than 1 to 78 percent with the probabilities increasing with each increase in storm magnitude. Probabilities were high in three of the six watersheds. For the 25-year storm, probabilities were greater than 60 percent for 11 basin outlets and ranged from 50 to 60 percent for an additional 12 basin outlets. Probability estimates for stream segments within the drainage network can vary within a basin. For the 25-year storm, probabilities for stream segments within 33 basins were higher than the basin outlet, emphasizing the importance of evaluating the drainage network as well as basin outlets. Estimated debris-flow volumes for the three modeled storms range

  8. Bed-material entrainment and associated transportation infrastructure problems in streams of the Edwards Plateau, central Texas

    Science.gov (United States)

    Heitmuller, Franklin T.; Asquith, William H.

    2008-01-01

    The Texas Department of Transportation commonly builds and maintains low-water crossings (LWCs) over streams in the Edwards Plateau in Central Texas. LWCs are low-height structures, typically constructed of concrete and asphalt, that provide acceptable passage over seasonal rivers or streams with relatively low normal-depth flow. They are designed to accommodate flow by roadway overtopping during high-flow events. The streams of the Edwards Plateau are characterized by cobble- and gravel-sized bed material and highly variable flow regimes. Low base flows that occur most of the time occasionally are interrupted by severe floods. The floods entrain and transport substantial loads of bed material in the stream channels. As a result, LWCs over streams in the Edwards Plateau are bombarded and abraded by bed material during floods and periodically must be maintained or even replaced.

  9. Melt-Flow Behaviours of Thermoplastic Materials under Fire Conditions: Recent Experimental Studies and Some Theoretical Approaches

    Directory of Open Access Journals (Sweden)

    Paul Joseph

    2015-12-01

    Full Text Available Polymeric materials often exhibit complex combustion behaviours encompassing several stages and involving solid phase, gas phase and interphase. A wide range of qualitative, semi-quantitative and quantitative testing techniques are currently available, both at the laboratory scale and for commercial purposes, for evaluating the decomposition and combustion behaviours of polymeric materials. They include, but are not limited to, techniques such as: thermo-gravimetric analysis (TGA, oxygen bomb calorimetry, limiting oxygen index measurements (LOI, Underwriters Laboratory 94 (UL-94 tests, cone calorimetry, etc. However, none of the above mentioned techniques are capable of quantitatively deciphering the underpinning physiochemical processes leading to the melt flow behaviour of thermoplastics. Melt-flow of polymeric materials can constitute a serious secondary hazard in fire scenarios, for example, if they are present as component parts of a ceiling in an enclosure. In recent years, more quantitative attempts to measure the mass loss and melt-drip behaviour of some commercially important chain- and step-growth polymers have been accomplished. The present article focuses, primarily, on the experimental and some theoretical aspects of melt-flow behaviours of thermoplastics under heat/fire conditions.

  10. Melt-Flow Behaviours of Thermoplastic Materials under Fire Conditions: Recent Experimental Studies and Some Theoretical Approaches.

    Science.gov (United States)

    Joseph, Paul; Tretsiakova-McNally, Svetlana

    2015-12-15

    Polymeric materials often exhibit complex combustion behaviours encompassing several stages and involving solid phase, gas phase and interphase. A wide range of qualitative, semi-quantitative and quantitative testing techniques are currently available, both at the laboratory scale and for commercial purposes, for evaluating the decomposition and combustion behaviours of polymeric materials. They include, but are not limited to, techniques such as: thermo-gravimetric analysis (TGA), oxygen bomb calorimetry, limiting oxygen index measurements (LOI), Underwriters Laboratory 94 (UL-94) tests, cone calorimetry, etc. However, none of the above mentioned techniques are capable of quantitatively deciphering the underpinning physiochemical processes leading to the melt flow behaviour of thermoplastics. Melt-flow of polymeric materials can constitute a serious secondary hazard in fire scenarios, for example, if they are present as component parts of a ceiling in an enclosure. In recent years, more quantitative attempts to measure the mass loss and melt-drip behaviour of some commercially important chain- and step-growth polymers have been accomplished. The present article focuses, primarily, on the experimental and some theoretical aspects of melt-flow behaviours of thermoplastics under heat/fire conditions.

  11. Queueing-Based Synchronization and Entrainment for Synthetic Gene Oscillators

    Science.gov (United States)

    Mather, William; Butzin, Nicholas; Hochendoner, Philip; Ogle, Curtis

    Synthetic gene oscillators have been a major focus of synthetic biology research since the beginning of the field 15 years ago. They have proven to be useful both for biotechnological applications as well as a testing ground to significantly develop our understanding of the design principles behind synthetic and native gene oscillators. In particular, the principles governing synchronization and entrainment of biological oscillators have been explored using a synthetic biology approach. Our work combines experimental and theoretical approaches to specifically investigate how a bottleneck for protein degradation, which is present in most if not all existing synthetic oscillators, can be leveraged to robustly synchronize and entrain biological oscillators. We use both the terminology and mathematical tools of queueing theory to intuitively explain the role of this bottleneck in both synchronization and entrainment, which extends prior work demonstrating the usefulness of queueing theory in synthetic and native gene circuits. We conclude with an investigation of how synchronization and entrainment may be sensitive to the presence of multiple proteolytic pathways in a cell that couple weakly through crosstalk. This work was supported by NSF Grant #1330180.

  12. Gasification of peat and biomass in suspension flow 2; Turpeen ja biomassan suspensiokaasutus 2

    Energy Technology Data Exchange (ETDEWEB)

    Kurkela, E.; Hepola, J. [VTT Energy, Espoo (Finland); Haukka, P.; Raiko, R. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Thermal Engineering

    1995-11-01

    This project is an extension of the earlier Liekki-project 402, which was carried out in 1993-1994 in the Department of Thermal Engineering of Tampere University of Technology (TUT). In the previous project the feasibility of a two-stage entrained-flow gasification was studied by the means of process modeling and pyrolysis experiments. The present project carried out in cooperation with the Gasification Research Group of VTT and TUT. The aims of the project are: (a) to study the formation of blematic tar/soot compounds and nitrogen compounds in the conditions entrained flow gasification of biomass and peat, (b) to study the product yields and kinetics of pyrolysis and (c) to develop simulation methods for entrained flow pyrolysis and gasification. (author)

  13. Investigation of the liquid film flow rate in an annular two phase flow

    International Nuclear Information System (INIS)

    Chandraker, D.K.; Dasgupta, A.; Vijayan, P.K.; Aritomi, M.

    2011-01-01

    An accurate knowledge of the liquid film flow is essential in most thermal-hydraulic predictions, including the onset of dryout in boiling channels and post-dryout heat transfer during transient and accident scenarios. The determination of the film flow is an important aspect of the dryout analysis in the boiling channel. Dryout is caused due to the disappearance of the liquid film on the heated surface. Mechanistic prediction of dryout involves the modeling of the physical phenomenon of the processes like entrainment and deposition rate of droplets. In the nuclear reactor systems analytical prediction of the thermal hydraulic parameters is always desirable to avoid generation of exhaustive and expensive experimental data for optimizing the design parameters. Good constitutive models for entrainment and deposition are vital for an accurate prediction of the film flow rate and hence dryout in a fuel bundle. This paper attempts a comprehensive review of the dryout analysis involving application of the constitutive models for the film flow rate. Validation of these models against various experimental data has also been presented in this paper. (author)

  14. Normalization of water flow rate for external fire fighting of the buildings in settlements with zone water supply

    Directory of Open Access Journals (Sweden)

    Deryushev Leonid Georgievich

    2014-12-01

    Full Text Available In the article the requirements for fire safety assurance are justified for the objects, in which water is supplied with account for serial and parallel area zoning. In the process of zoning the district is segregated into such parts, for which head rate in any point of selection of water from network will not exceed 6 bar. In the current regulatory rules the requirements for the calculation of the costs of water points are stated, as well as in case of extinguishing fires at the sites with water-supply systems zones. It is recommended to analyze each zone of the system of water-supply separately, without interrelation with the common water feeders, water consumers and services of fire extinguishing. Such an approach to assign water discharge for fire extinguishing results in the decrease of fire safety of an object, deforms calculation technique of outside systems of water-supply of the similar-type objects located in different parts of the terrain. Taking the number of fires and water consumption for fire suppression by the number of residents in each zone, we thus underestimate the capacity of the pipeline system. It is offered to make changes in Norms and Standards in force on fire safety of settlements. The recommendations on regulation of the number of fires and water flow for fire fighting in residential objects with zoned systems of water-supply are formulated.

  15. Is the food-entrainable circadian oscillator in the digestive system?

    Science.gov (United States)

    Davidson, A. J.; Poole, A. S.; Yamazaki, S.; Menaker, M.

    2003-01-01

    Food-anticipatory activity (FAA) is the increase in locomotion and core body temperature that precedes a daily scheduled meal. It is driven by a circadian oscillator but is independent of the suprachiasmatic nuclei. Recent results that reveal meal-entrained clock gene expression in rat and mouse peripheral organs raise the intriguing possibility that the digestive system is the site of the feeding-entrained oscillator (FEO) that underlies FAA. We tested this possibility by comparing FAA and Per1 rhythmicity in the digestive system of the Per1-luciferase transgenic rat. First, rats were entrained to daytime restricted feeding (RF, 10 days), then fed ad libitum (AL, 10 days), then food deprived (FD, 2 days). As expected FAA was evident during RF and disappeared during subsequent AL feeding, but returned at the correct phase during deprivation. The phase of Per1 in liver, stomach and colon shifted from a nocturnal to a diurnal peak during RF, but shifted back to nocturnal phase during the subsequent AL and remained nocturnal during food deprivation periods. Second, rats were entrained to two daily meals at zeitgeber time (ZT) 0400 and ZT 1600. FAA to both meals emerged after about 10days of dual RF. However, all tissues studied (all five liver lobes, esophagus, antral stomach, body of stomach, colon) showed entrainment consistent with only the night-time meal. These two results are inconsistent with the hypothesis that FAA arises as an output of rhythms in the gastrointestinal (GI) system. The results also highlight an interesting diversity among peripheral oscillators in their ability to entrain to meals and the direction of the phase shift after RF ends.

  16. Laboratory study of orographic cloud-like flow

    Science.gov (United States)

    Singh, Kanwar Nain; Sreenivas, K. R.

    2013-11-01

    Clouds are one of the major sources of uncertainty in climate prediction, listed in ``the most urgent scientific problems requiring attention'' IPCC. Also, convective clouds are of utmost importance to study the dynamics of tropical meteorology and therefore, play a key role in understanding monsoons. The present work is to study the dynamics of orographic clouds. Parameterization of these clouds will help in forecasting the precipitation accurately. Also, one could validate laboratory results from our study by actually measuring cloud development along a sloping terrain. In this context a planar buoyant turbulent wall jet is considered as an appropriate low order fluid-dynamical model for studying the turbulence and entrainment in orographic-clouds. Flow is volumetrically heated to mimic the latent heat release due to condensation in an actual cloud. This is the first step in studying the entrainment dynamics of the evolving orographic cloud. We are going to present some results on the cloud development using techniques that allows us to construct a 3-dimensional flow field at each instance and its development over the time. By combining velocity field from PIV and flow volume from PLIF at successive instances, we estimate the entrainment coefficient. Since the life-cycle of a cloud is determined by the entrainment of ambient air, these results could be extremely helpful in understanding the dynamics of the clouds. Detailed results will be presented at the conference.

  17. The role of high-level processes for oscillatory phase entrainment to speech sound

    Directory of Open Access Journals (Sweden)

    Benedikt eZoefel

    2015-12-01

    Full Text Available Constantly bombarded with input, the brain has the need to filter out relevant information while ignoring the irrelevant rest. A powerful tool may be represented by neural oscillations which entrain their high-excitability phase to important input while their low-excitability phase attenuates irrelevant information. Indeed, the alignment between brain oscillations and speech improves intelligibility and helps dissociating speakers during a cocktail party. Although well-investigated, the contribution of low- and high-level processes to phase entrainment to speech sound has only recently begun to be understood. Here, we review those findings, and concentrate on three main results: (1 Phase entrainment to speech sound is modulated by attention or predictions, likely supported by top-down signals and indicating higher-level processes involved in the brain’s adjustment to speech. (2 As phase entrainment to speech can be observed without systematic fluctuations in sound amplitude or spectral content, it does not only reflect a passive steady-state ringing of the cochlea, but entails a higher-level process. (3 The role of intelligibility for phase entrainment is debated. Recent results suggest that intelligibility modulates the behavioral consequences of entrainment, rather than directly affecting the strength of entrainment in auditory regions. We conclude that phase entrainment to speech reflects a sophisticated mechanism: Several high-level processes interact to optimally align neural oscillations with predicted events of high relevance, even when they are hidden in a continuous stream of background noise.

  18. Searching for roots of entrainment and joint action in early musical interactions

    Directory of Open Access Journals (Sweden)

    Jessica ePhillips-Silver

    2012-02-01

    Full Text Available When people play music and dance together, they engage in forms of musical joint action that are often characterized by a shared sense of rhythmic timing and affective state (i.e., temporal and affective entrainment. In order to understand the origins of musical joint action, we propose a model in which entrainment is linked to dual mechanisms (motor resonance and action simulation, which in turn support musical behavior (imitation and complementary joint action. To illustrate this model, we consider two generic forms of joint musical behavior: chorusing and turn-taking. We explore how these common behaviors can be founded on entrainment capacities established early in human development, specifically during musical interactions between infants and their caregivers. If the roots of entrainment are found in early musical interactions which are practiced from childhood into adulthood, then we propose that the rehearsal of advanced musical ensemble skills can be considered to be a refined, mimetic form of temporal and affective entrainment whose evolution begins in infancy.

  19. The value of high-flow nasal cannula oxygen therapy after extubation in patients with acute respiratory failure

    Directory of Open Access Journals (Sweden)

    Hong-Zhuan Song

    Full Text Available OBJECTIVE: To investigate the value of high-flow nasal cannula oxygen therapy after extubation in patients with acute respiratory failure. METHODS: A single-center, prospective, randomized, controlled pilot trial was conducted between January 2013 and December 2014. Sixty enrolled patients were randomized immediately after extubation into either a high-flow nasal cannula group (n=30 or an air entrainment mask group (n=30 at a fixed inspired oxygen fraction (40%. The success rate of oxygen therapy, respiratory and hemodynamic parameters and subjective discomfort (using a visual analogue scale were assessed at 24h after extubation. RESULTS: The two groups were comparable at extubation. A total of 46 patients were successfully treated including 27 patients in the high-flow nasal cannula group and 19 patients in the air entrainment mask group. Compared to the air entrainment mask group, the success rate of oxygen therapy and the partial pressure of arterial oxygen were significantly higher and the respiratory rate was lower in the high-flow nasal cannula group. In addition, less discomfort related to interface displacement and airway dryness was observed in the high-flow nasal cannula group than in the air entrainment mask group. CONCLUSIONS: At a fixed inspired oxygen fraction, the application of a high-flow nasal cannula after extubation achieves a higher success rate of oxygen therapy and less discomfort at 24h than an air entrainment mask in patients with acute respiratory failure.

  20. Production and Transport of Ozone From Boreal Forest Fires

    Science.gov (United States)

    Tarasick, David; Liu, Jane; Osman, Mohammed; Sioris, Christopher; Liu, Xiong; Najafabadi, Omid; Parrington, Mark; Palmer, Paul; Strawbridge, Kevin; Duck, Thomas

    2013-04-01

    In the summer of 2010, the BORTAS (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) mission was planned by several universities and government agencies in the United Kingdom, Canada, and USA. Nearly 100 ozone soundings were made at 13 stations through the BORTAS Intensive Sounding Network, although aircraft measurements were unfortunately cancelled due to the volcanic eruption in Iceland. 2010 was actually an exceptional year for Canadian boreal fires. MODIS (Moderate Resolution Imaging Spectroradiometer) fire count data shows large fire events in Saskatchewan on several days in July. High amounts of NO2 close to the large fires are observed from OMI satellite data, indicating that not all NO2 is converted to PAN. Also associated with the fires, large amounts of CO, another precursor of ozone, are observed in MOPITT (Measurements Of Pollution In The Troposphere), AIRS and TES (Tropospheric Emission Spectrometer) satellite data in the middle to upper troposphere. These chemical conditions combined with sunny weather all favour ozone production. Following days with large fire activity, layers of elevated ozone mixing ratio (over 100 ppbv) are observed downwind at several sites. Back-trajectories suggest the elevated ozone in the profile is traceable to the fires in Saskatchewan. Lidar profiles also detect layers of aerosol at the same heights. However, the layers of high ozone are also associated with low humidity, which is not expected from a combustion source, and suggests the possibility of entrainment of stratospheric air.

  1. Analysis of clad motion observed in loss of flow accident simulation experiments

    International Nuclear Information System (INIS)

    Henkel, P.R.

    1987-01-01

    The clad motion observed in the first two STAR experiments is analysed. The movies reveal that at moderate temperatures molten cladding does not wet fresh fuel (within an argon gas atmosphere). The prevailing flow regime consists of single waves contacting the fuel pins and entrained drops. Entrainment is possible already at gas velocities of order 40-50 m/s. A multichannel clad motion model is presented that accounts for both flow modes. (author)

  2. Freeze-thaw durability of air-entrained concrete.

    Science.gov (United States)

    Shang, Huai-Shuai; Yi, Ting-Hua

    2013-01-01

    One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles). The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to "the test method of long-term and durability on ordinary concrete" GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results.

  3. Advances in field and analytical methods for estimating entrainment mortality factors

    International Nuclear Information System (INIS)

    Muessig, P.H.; Young, J.R.; Vaughan, D.S.; Smith, B.A.

    1988-01-01

    The hearings and settlement negotiations in the Hudson River case focused on various modeling input factors for calculating reduction in year-class strength of important fish species in the Hudson River due to power plant operations. One of the inputs that received considerable attention, and about which the various parties to the case came to general agreement, was the entrainment mortality factor, or f-factor, the probability that an entrained live organism will be killed as a result of its passage through a power plant in the condenser cooling water. Entrainment mortality includes death due to temperature increases and death due to mechanical processes. The convergence of views about the f-factor arose from increased understanding of the sources of estimation error, improvements in gear for collection of fish larvae, and development of a model for the thermal component of entrainment mortality. Improvements in sampling-gear design reduced potential biases in mortality estimates, reduced estimates of mechanical mortality from 0.923 to 0.412, and improved the statistical power to detect entrainment mortality and the precision of mortality estimates. 20 refs., 7 figs., 1 tab

  4. The role of the endocrine system in feeding-induced tissue-specific circadian entrainment.

    Science.gov (United States)

    Sato, Miho; Murakami, Mariko; Node, Koichi; Matsumura, Ritsuko; Akashi, Makoto

    2014-07-24

    The circadian clock is entrained to environmental cycles by external cue-mediated phase adjustment. Although the light input pathway has been well defined, the mechanism of feeding-induced phase resetting remains unclear. The tissue-specific sensitivity of peripheral entrainment to feeding suggests the involvement of multiple pathways, including humoral and neuronal signals. Previous in vitro studies with cultured cells indicate that endocrine factors may function as entrainment cues for peripheral clocks. However, blood-borne factors that are well characterized in actual feeding-induced resetting have yet to be identified. Here, we report that insulin may be involved in feeding-induced tissue-type-dependent entrainment in vivo. In ex vivo culture experiments, insulin-induced phase shift in peripheral clocks was dependent on tissue type, which was consistent with tissue-specific insulin sensitivity, and peripheral entrainment in insulin-sensitive tissues involved PI3K- and MAPK-mediated signaling pathways. These results suggest that insulin may be an immediate early factor in feeding-mediated tissue-specific entrainment. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  5. The effect of low-NOx combustion on residual carbon in fly ash and its adsorption capacity for air entrainment admixtures in concrete

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard; Jensen, Anker Degn; Dam-Johansen, Kim

    2010-01-01

    been combusted in an entrained flow reactor to test the impact of changes in operating conditions and fuel type on the AEA adsorption of ash and NOx formation. Increased oxidizing conditions, obtained by improved fuel-air mixing or higher excess air, decreased the AEA requirements of the produced ash......Fly ash from pulverized coal combustion contains residual carbon that can adsorb the air-entraining admixtures (AEAs) added to control the air entrainment in concrete. This is a problem that has increased by the implementation of low-NOx combustion technologies. In this work, pulverized fuel has...... by up to a factor of 25. This was due to a lower carbon content in the ash and a lower specific AEA adsorptivity of the carbon. The latter was suggested to be caused by changes in the adsorption properties of the unburned char and a decreased formation of soot, which was found to have a large AEA...

  6. Timescales of Massive Human Entrainment

    DEFF Research Database (Denmark)

    Fusaroli, Riccardo; Perlman, Marcus; Mislove, Alan

    2014-01-01

    of distinct scales, in an exquisitely time locked fashion. Using a large scale database of human communication data, we analyze and describe three different time scales of human entrainment in electronic media. We sought a distinct shared experience that provided a test bed for quantifying large scale human...

  7. Flooding and flow reversal of two-phase annular flow

    International Nuclear Information System (INIS)

    Asahi, Y.

    1978-01-01

    The flooding and flow reversal conditions of two-phase annular flow are mathematically defined in terms of a characteristic function representing a force balance. Sufficiently below the flooding point in counter-current flow, the interface is smooth and the characteristic equation reduces to the Nusselt relationship. Just below flooding point and above the flow reversal point in cocurrent flow, the interface is 'wavy', so that the interfacial shear effect plays an important role. The theoretical analysis is compared with experimental results by others. It is suggested that the various length effects which have been experimentally observed may be accounted for by the spatial variation of the droplet entrainment. (Auth.)

  8. New insights on entrainment and condensation in volcanic plumes: Constraints from independent observations of explosive eruptions and implications for assessing their impacts

    Science.gov (United States)

    Aubry, Thomas J.; Jellinek, A. Mark

    2018-05-01

    The turbulent entrainment of atmosphere and the condensation of water vapor govern the heights of explosive volcanic plumes. These processes thus determine the delivery and the lifetime of volcanic ash and aerosols into the atmosphere. Predictions of plume heights using one-dimensional "integral" models of volcanic plumes, however, suffer from very large uncertainties, related to parameterizations for entrainment and condensation. In particular, the wind entrainment coefficient β, which governs the contribution of crosswinds to turbulent entrainment, is subject to uncertainties of one order of magnitude, leading to relative uncertainties of the order of 50% on plume height. In this study, we use a database of 94 eruptive phases with independent estimates of mass eruption rate and plume height to constrain and evaluate four popular 1D models. We employ re-sampling methods to account for observational uncertainties. We show that plume height predictions are significantly improved when: i) the contribution of water vapor condensation to the plume buoyancy flux is excluded; and ii) the wind entrainment coefficient β is held constant between 0.1 and 0.4. We explore implications of these results for predicting the climate impacts of explosive eruptions and the likelihood that eruptions will form stable umbrella clouds or devastating pyroclastic flows. Last, we discuss the sensitivity of our results to the definition of plume height in the model in light of a recent set of laboratory experiments and draw conclusions for improving future databases of eruption parameters.

  9. Estimation of convective entrainment properties from a cloud-resolving model simulation during TWP-ICE

    Science.gov (United States)

    Zhang, Guang J.; Wu, Xiaoqing; Zeng, Xiping; Mitovski, Toni

    2016-10-01

    The fractional entrainment rate in convective clouds is an important parameter in current convective parameterization schemes of climate models. In this paper, it is estimated using a 1-km-resolution cloud-resolving model (CRM) simulation of convective clouds from TWP-ICE (the Tropical Warm Pool-International Cloud Experiment). The clouds are divided into different types, characterized by cloud-top heights. The entrainment rates and moist static energy that is entrained or detrained are determined by analyzing the budget of moist static energy for each cloud type. Results show that the entrained air is a mixture of approximately equal amount of cloud air and environmental air, and the detrained air is a mixture of ~80 % of cloud air and 20 % of the air with saturation moist static energy at the environmental temperature. After taking into account the difference in moist static energy between the entrained air and the mean environment, the estimated fractional entrainment rate is much larger than those used in current convective parameterization schemes. High-resolution (100 m) large-eddy simulation of TWP-ICE convection was also analyzed to support the CRM results. It is shown that the characteristics of entrainment rates estimated using both the high-resolution data and CRM-resolution coarse-grained data are similar. For each cloud category, the entrainment rate is high near cloud base and top, but low in the middle of clouds. The entrainment rates are best fitted to the inverse of in-cloud vertical velocity by a second order polynomial.

  10. Release of radioactive materials in simulation test of a postulated solvent fire in a nuclear fuel reprocessing plant

    International Nuclear Information System (INIS)

    Nishio, G.; Hashimoto, K.

    1989-01-01

    This paper reports on small- and large-scale fire tests performed to examine the adequacy of a safety evaluation method for a solvent fire in the extraction process of a nuclear fuel reprocessing plant. The test objectives were to obtain information on the confinement of radioactive materials during a 30% tri-n-butyl phosphate-n-dodecane fire while air ventilation is operating in the cell. The rates of release of cesium, strontium, cerium, ruthenium, and uranium from a burning solvent were determined. The quantities of species released were obtained from the solvent burning rate, smoke generation rate, partition coefficients of species between solvent and water, and coefficients of species entrainment to atmosphere in cell

  11. Cyclonic entrainment of preconditioned shelf waters into a frontal eddy

    Science.gov (United States)

    Everett, J. D.; Macdonald, H.; Baird, M. E.; Humphries, J.; Roughan, M.; Suthers, I. M.

    2015-02-01

    The volume transport of nutrient-rich continental shelf water into a cyclonic frontal eddy (entrainment) was examined from satellite observations, a Slocum glider and numerical simulation outputs. Within the frontal eddy, parcels of water with temperature/salinity signatures of the continental shelf (18-19°C and >35.5, respectively) were recorded. The distribution of patches of shelf water observed within the eddy was consistent with the spiral pattern shown within the numerical simulations. A numerical dye tracer experiment showed that the surface waters (≤50 m depth) of the frontal eddy are almost entirely (≥95%) shelf waters. Particle tracking experiments showed that water was drawn into the eddy from over 4° of latitude (30-34.5°S). Consistent with the glider observations, the modeled particles entrained into the eddy sunk relative to their initial position. Particles released south of 33°S, where the waters are cooler and denser, sunk 34 m deeper than their release position. Distance to the shelf was a critical factor in determining the volume of shelf water entrained into the eddy. Entrainment reduced to 0.23 Sv when the eddy was furthest from the shelf, compared to 0.61 Sv when the eddy was within 10 km of the shelf. From a biological perspective, quantifying the entrainment of shelf water into frontal eddies is important, as it is thought to play a significant role in providing an offshore nursery habitat for coastally spawned larval fish.

  12. Incipient motion in gravel bed rivers due to energetic turbulent flow events

    Science.gov (United States)

    Valyrakis, Manousos

    2013-04-01

    This contribution reviews recent developments and contributions in the field of incipient motion and entrainment of coarse sediment grains due to the action of near bed turbulent flows. Specifically, traditional shear based spatio-temporally averaged concepts and instantaneous stress tensor criteria are contrasted to the newly proposed flow event based impulse and energy criteria. The energy criterion, suggests that only sufficiently energetic turbulent events can remove a particle from its resting position on the bed surface and result on its entrainment downstream. While the impulse and energy criteria are interconnected through the energy-impulse equation, the later appears to be more versatile and appropriate for generalising to sediment transport. These flow event based criteria have a sound physical basis for describing the intermittent character of particle entrainment as inherited by near boundary turbulence at near threshold conditions. These criteria can be derived from fundamental laws of physics such as Newtonian classical mechanics and the Lagrange equations respectively. The energetic events that are capable of performing geomorphic work at the scale of individual particles are shown to follow a power law, meaning that more energetic events (capable of removing larger stones) are expected to occur less frequently. In addition, this paper discusses the role of the coefficient of energy transfer efficiency introduced in the energy equation for particle entrainment. A preliminary investigation from analysis of a series of mobile grain flume experiments illustrates that different signatures of turbulence or sequence of flow structures may have different effectiveness towards particle transport. Characteristic cases of specific energetic flow events and the associated particle response are shown and classified with regard to the time required for complete entrainment. Finally these findings are commented with respect to the implications for sediment

  13. The influence of Savannah River discharge and changing SRS cooling water requirements on the potential entrainment of ichthyoplankton at the SRS Savannah River intakes

    International Nuclear Information System (INIS)

    Paller, M.H.

    1992-08-01

    Entrainment (i.e., withdrawal of fish larvae and eggs in cooling water) at the SRS Savannah River intakes is greatest when periods of high river water usage coincide with low river dischargeduring the spawning season. American shad and striped bass are the two species of greatest concern because of their recreational and/or commercial importance and because they produce drifting eggs and larvae vulnerable to entrainment. In the mid-reaches of the Savannah River, American shad and striped bass spawn primarily during April and May. An analysis of Savannah River discharge during April and May 1973--1989 indicated the potential for entrainment of 4--18% of the American shad and striped bass larvae and eggs that drifted past the SRS. This analysis assumed the concurrent operation of L-, K-, and P-Reactors. Additional scenarios investigated were: (1) shutting down L- and P-Reactors, and operating K-Reactor with a recycle cooling tower; and (2) shutting down L- and P-Reactors, eliminating minimum flows to Steel Creek, and operating K-Reactor with a recycle cooling tower. The former scenario reduced potential entrainment to 0.7--3.3%, and the latter scenario reduced potential entrainment to 0.20.8%. Thus, the currently favored scenario of operating K-Reactor with a cooling tower and not operating L- and P-Reactors represents a significant lessening of the impact of SRS operations

  14. Word-by-word entrainment of speech rhythm during joint story building

    Directory of Open Access Journals (Sweden)

    Tommi eHimberg

    2015-06-01

    Full Text Available Movements and behaviour synchronise during social interaction at many levels, often unintentionally. During smooth conversation, for example, participants adapt to each others' speech rates. Here we aimed to find out to which extent speakers adapt their turn-taking rhythms during a story-building game.Nine sex-matched dyads of adults (12 males, 6 females created two 5-min stories by contributing to them alternatingly one word at a time. The participants were located in different rooms, with audio connection during one story and audiovisual during the other. They were free to select the topic of the story.Although the participants received no instructions regarding the timing of the story building, their word rhythms were highly entrained (R ̅ = 0.70, p < 0.001 even though the rhythms as such were unstable (R ̅ = 0.14 for pooled data. Such high entrainment in the absence of steady word rhythm occurred in every individual story, independently of whether the subjects were connected via audio-only or audiovisual link.The observed entrainment was of similar strength as typical entrainment in finger-tapping tasks where participants are specifically instructed to synchronize their behaviour. Thus speech seems to spontaneously induce strong entrainment between the conversation partners, likely reflecting automatic alignment of their semantic and syntactic processes.

  15. Reducing the Entrainment of Gangue Fines in Low Grade Microcrystalline Graphite Ore Flotation Using Multi-Stage Grinding-Flotation Process

    Directory of Open Access Journals (Sweden)

    Xiaoqing Weng

    2017-03-01

    Full Text Available A suitable grinding fineness and flow-sheet could potentially reduce the mechanical entrainment of gangue minerals in the flotation process of microcrystalline graphite. In this study, the suitable grinding fineness of a commercial graphite ore was estimated by mineralogy analysis and laboratory grind-flotation tests. The target grind size of this ore should be 92% passing 74 μm based on the mineralogical evaluation and the flotation performance. A comparison of a single-stage and a three-stage grinding circuit was conducted. Experimental results demonstrated that the three-stage grinding circuit could effectively improve the separation effect, which was attributed to the reduction of slimes. In the end, a more desirable beneficiation result was obtained with the application of three-stage grinding-flotation process by minimizing gangue entrainment.

  16. Neural entrainment to the rhythmic structure of music.

    Science.gov (United States)

    Tierney, Adam; Kraus, Nina

    2015-02-01

    The neural resonance theory of musical meter explains musical beat tracking as the result of entrainment of neural oscillations to the beat frequency and its higher harmonics. This theory has gained empirical support from experiments using simple, abstract stimuli. However, to date there has been no empirical evidence for a role of neural entrainment in the perception of the beat of ecologically valid music. Here we presented participants with a single pop song with a superimposed bassoon sound. This stimulus was either lined up with the beat of the music or shifted away from the beat by 25% of the average interbeat interval. Both conditions elicited a neural response at the beat frequency. However, although the on-the-beat condition elicited a clear response at the first harmonic of the beat, this frequency was absent in the neural response to the off-the-beat condition. These results support a role for neural entrainment in tracking the metrical structure of real music and show that neural meter tracking can be disrupted by the presentation of contradictory rhythmic cues.

  17. Soot, organics, and ultrafine ash from air- and oxy-fired coal combustion

    Data.gov (United States)

    U.S. Environmental Protection Agency — Pulverized bituminous coal was burned in a 10W externally heated entrained flow furnace under air-combustion and three oxy-combustion inlet oxygen conditions (28,...

  18. New models of droplet deposition and entrainment for prediction of CHF in cylindrical rod bundles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haibin, E-mail: hb-zhang@xjtu.edu.cn [School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049 (China); Department of Chemical Engineering, Imperial College, London SW7 2BY (United Kingdom); Hewitt, G.F. [Department of Chemical Engineering, Imperial College, London SW7 2BY (United Kingdom)

    2016-08-15

    Highlights: • New models of droplet deposition and entrainment in rod bundles is developed. • A new phenomenological model to predict the CHF in rod bundles is described. • The present model is well able to predict CHF in rod bundles. - Abstract: In this paper, we present a new set of model of droplet deposition and entrainment in cylindrical rod bundles based on the previously proposed model for annuli (effectively a “one-rod” bundle) (2016a). These models make it possible to evaluate the differences of the rates of droplet deposition and entrainment for the respective rods and for the outer tube by taking into account the geometrical characteristics of the rod bundles. Using these models, a phenomenological model to predict the CHF (critical heat flux) for upward annular flow in vertical rod bundles is described. The performance of the model is tested against the experimental data of Becker et al. (1964) for CHF in 3-rod and 7-rod bundles. These data include tests in which only the rods were heated and data for simultaneous uniform and non-uniform heating of the rods and the outer tube. It was shown that the predicted CHFs by the present model agree well with the experimental data and with the experimental observation that dryout occurred first on the outer rods in 7-rod bundles. It is expected that the methodology used will be generally applicable in the prediction of CHF in rod bundles.

  19. Freeze-Thaw Durability of Air-Entrained Concrete

    Directory of Open Access Journals (Sweden)

    Huai-Shuai Shang

    2013-01-01

    Full Text Available One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles. The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss and internal crack growth (characterized by the loss of dynamic modulus of elasticity. The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to “the test method of long-term and durability on ordinary concrete” GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results.

  20. Postwildfire preliminary debris flow hazard assessment for the area burned by the 2011 Las Conchas Fire in north-central New Mexico

    Science.gov (United States)

    Tillery, Anne C.; Darr, Michael J.; Cannon, Susan H.; Michael, John A.

    2011-01-01

    The Las Conchas Fire during the summer of 2011 was the largest in recorded history for the state of New Mexico, burning 634 square kilometers in the Jemez Mountains of north-central New Mexico. The burned landscape is now at risk of damage from postwildfire erosion, such as that caused by debris flows and flash floods. This report presents a preliminary hazard assessment of the debris-flow potential from 321 basins burned by the Las Conchas Fire. A pair of empirical hazard-assessment models developed using data from recently burned basins throughout the intermountain western United States was used to estimate the probability of debris-flow occurrence and volume of debris flows at the outlets of selected drainage basins within the burned area. The models incorporate measures of burn severity, topography, soils, and storm rainfall to estimate the probability and volume of debris flows following the fire. In response to a design storm of 28.0 millimeters of rain in 30 minutes (10-year recurrence interval), the probabilities of debris flows estimated for basins burned by the Las Conchas Fire were greater than 80 percent for two-thirds (67 percent) of the modeled basins. Basins with a high (greater than 80 percent) probability of debris-flow occurrence were concentrated in tributaries to Santa Clara and Rio del Oso Canyons in the northeastern part of the burned area; some steep areas in the Valles Caldera National Preserve, Los Alamos, and Guaje Canyons in the east-central part of the burned area; tributaries to Peralta, Colle, Bland, and Cochiti canyons in the southwestern part of the burned area; and tributaries to Frijoles, Alamo, and Capulin Canyons in the southeastern part of the burned area (within Bandelier National Monument). Estimated debris-flow volumes ranged from 400 cubic meters to greater than 72,000 cubic meters. The largest volumes (greater than 40,000 cubic meters) were estimated for basins in Santa Clara, Los Alamos, and Water Canyons, and for two

  1. Rewetting and liquid entrainment during reflooding: state of the art

    International Nuclear Information System (INIS)

    Elias, E.; Yadigaroglu, G.

    1977-05-01

    Considerable interest has recently been generated in the problems of surface rewetting and the physics of liquid droplet entrainment due to their role in light water nuclear reactor safety. Published models of the rewetting process include simple one-dimensional solutions in two axial regions, one-dimensional solutions in three axial regions with or without precursory cooling, one- and two-dimensional numerical-difference techniques using temperature dependent heat transfer coefficients, and analytical two-dimensional solutions. The basic assumptions of these models and the numerical values assigned to the various parameters, as well as empirical rewetting correlations, are discussed. The various mechanisms for liquid droplet entrainment and analytical formulations of the critical gas velocity and of the droplet diameter at the onset of entrainment are reviewed

  2. Assessment of ichthyoplankton entrainment at Pickering 'A' NGS using a pump/net in lake system

    International Nuclear Information System (INIS)

    McKinley, R.S.

    1985-03-01

    Annual entrainment at Pickering 'A' NGS was estimated for alewife as 13.6 X 10 6 larvae and 409 X 10 6 eggs. A substantial portion of eggs and larvae entering the intake were dead due to natural mortality (41%-81%) prior to entrainment. Viable eggs and larvae, immediately following entrainment showed mortalities of 54% and 44% respectively. The latent mortality of entrained eggs was 100% (48 h)

  3. Large Eddy Simulations of sediment entrainment induced by a lock-exchange gravity current

    Science.gov (United States)

    Kyrousi, Foteini; Leonardi, A.; Roman, F.; Armenio, V.; Zanello, F.; Zordan, J.; Juez, C.; Falcomer, L.

    2018-04-01

    Large Eddy simulations of lock-exchange gravity currents propagating over a mobile reach are presented. The numerical setting allows to investigate the sediment pick up induced by the currents and to study the underlying mechanisms leading to sediment entrainment for different Grashof numbers and grain sizes. First, the velocity field and the bed shear-stress distribution are investigated, along with turbulent structures formed in the flow, before the current reaches the mobile bed. Then, during the propagation of the current above the erodible section of the bed the contour plots of the entrained material are presented as well as the time evolution of the areas covered by the current and by the sediment at this section. The numerical outcomes are compared with experimental data showing a very good agreement. Overall, the study confirms that sediment pick up is prevalent at the head of the current where the strongest turbulence occurs. Further, above the mobile reach of the bed, settling process seems to be of minor importance, with the entrained material being advected downstream by the current. Additionally, the study shows that, although shear stress is the main mechanism that sets particles in motion, turbulent bursts as well as vertical velocity fluctuations are also necessary to counteract the falling velocity of the particles and maintain them into suspension. Finally, the analysis of the stability conditions of the current shows that, from one side, sediment concentration gives a negligible contribution to the stability of the front of the current and from the other side, the stability conditions provided by the current do not allow sediments to move into the ambient fluid.

  4. The entrainment of air by water jet impinging on a free surface

    Energy Technology Data Exchange (ETDEWEB)

    Soh, Wee King [University of Wollongong, School of Mechanical, Materials and Mechatronics Engineering, Northfields Ave, NSW (Australia); Khoo, Boo Cheong [National University of Singapore, Department of Mechanical and Production Engineering, 10 Kent Ridge Crescent (Singapore); Yuen, W.Y. Daniel [BlueScope Steel Research, Port Kembla, NSW (Australia)

    2005-09-01

    High-speed cine and video photographs were used to capture the flow patterns of a column of water jet impinging into a pool of water. The impact results in air entrainment into water in the form of a void with no mixing between the water in the jet and the surrounding water. Conservation of fluid momentum shows that the rate of increase of the height of the air void depends on the drag coefficient of the jet front. By neglecting the frictional losses, the application of energy conservation yields an expression that relates the maximum height of the air void with the properties of the water jet. (orig.)

  5. Techno-economic analysis of lignite fuelled IGCC with CO{sub 2} capture. Comparing fluidized bed and entrained flow gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Guangjian; Wu, Zhen; Zhang, Haiying [North China Electric Power Univ., Beijing (China). School of Energy and Power Engineering

    2013-07-01

    Integrated coal gasification combined cycle (IGCC) plants with pre-combustion capture of CO{sub 2} represent one of the most promising options for generating low-cost decarbonized power using bituminous coals. This work systematically quantify the effect of coal rank on the efficiency and economics of IGCC systems with CO2 capture and storage (CCS), with a special focus on comparison of systems using fluidized-bed gasifier (U-GAS) and entrained flow gasifier (Shell). It was found that the Shell IGCCs are little affect by low rank coal after pre-drying in terms of thermal efficiency and the levelized cost of electricity (LCOE) is only increase by 2-6% for lignite cases with and without CCS compared with bituminous coal cases. The specific CO{sub 2} emissions of U-GAS gasifier based lignite fuelled IGCC with CCS is 198 g/kWhe, almost two times of shell gasifier cases, mainly due to lower carbon conversion in the gasifier and the higher methane in the raw gas of gasifier. However, the total capital cost and COE of U-Gas IGCCs are 15-20% less than that of Shell IGCCs because of lower capital cost of gasifier, coal drying units and air separate units per kWe.

  6. Numerical investigation on the flow, combustion, and NOX emission characteristics in a 660 MWe tangential firing ultra-supercritical boiler

    Directory of Open Access Journals (Sweden)

    Wenjing Sun

    2016-02-01

    Full Text Available A three-dimensional numerical simulation was carried out to study the pulverized-coal combustion process in a tangentially fired ultra-supercritical boiler. The realizable k-ε model for gas coupled with discrete phase model for coal particles, P-1 radiation model for radiation, two-competing-rates model for devolatilization, and kinetics/diffusion-limited model for combustion process are considered. The characteristics of the flow field, particle motion, temperature distribution, species components, and NOx emissions were numerically investigated. The good agreement of the measurements and predictions implies that the applied simulation models are appropriate for modeling commercial-scale coal boilers. It is found that an ideal turbulent flow and particle trajectory can be observed in this unconventional pulverized-coal furnace. With the application of over-fire air and additional air, lean-oxygen combustion takes place near the burner sets region and higher temperature at furnace exit is acquired for better heat transfer. Within the limits of secondary air, more steady combustion process is achieved as well as the reduction of NOx. Furthermore, the influences of the secondary air, over-fire air, and additional air on the NOx emissions are obtained. The numerical results reveal that NOx formation attenuates with the decrease in the secondary air ratio (γ2nd and the ratio of the additional air to the over-fire air (γAA/γOFA was within the limits.

  7. CONCEPTUAL DESIGN OF NON-IDEAL MIXTURE SEPARATION WITH LIGHT ENTRAINERS

    Directory of Open Access Journals (Sweden)

    W. Shen

    Full Text Available Abstract A method is proposed to study the separation of minimum-, maximum-boiling azeotropic, and low volatility mixtures with a light entrainer, to investigate feasible regions of the key operating parameters reboil ratio (S and entrainer - feed flowrate ratio (FE/F for continuous processes. The thermodynamic topological predictions are carried out for 1.0-2, 1.0-1a, and 0.0-1 Serafimov's class diagrams. It relies upon the knowledge of residue curve maps, along with the univolatility line, and it enables the prediction of possible products at the bottom of the column and limiting values of FE/F. The profiles of the stripping, extractive, and rectifying sections are calculated by equations considering S and FE/F, and they bring information about the location of singular points and possible composition profile separatrices that could impair process feasibility. Providing specified product composition and recovery, the approximate calculations are compared with rigorous simulations of extractive distillation processes. Separating non-ideal mixtures using a light entrainer provides more opportunities for the case when it is not easy to find an appropriate heavy or intermediate entrainer.

  8. Neural entrainment to rhythmically-presented auditory, visual and audio-visual speech in children

    Directory of Open Access Journals (Sweden)

    Alan James Power

    2012-07-01

    Full Text Available Auditory cortical oscillations have been proposed to play an important role in speech perception. It is suggested that the brain may take temporal ‘samples’ of information from the speech stream at different rates, phase-resetting ongoing oscillations so that they are aligned with similar frequency bands in the input (‘phase locking’. Information from these frequency bands is then bound together for speech perception. To date, there are no explorations of neural phase-locking and entrainment to speech input in children. However, it is clear from studies of language acquisition that infants use both visual speech information and auditory speech information in learning. In order to study neural entrainment to speech in typically-developing children, we use a rhythmic entrainment paradigm (underlying 2 Hz or delta rate based on repetition of the syllable ba, presented in either the auditory modality alone, the visual modality alone, or as auditory-visual speech (via a talking head. To ensure attention to the task, children aged 13 years were asked to press a button as fast as possible when the ba stimulus violated the rhythm for each stream type. Rhythmic violation depended on delaying the occurrence of a ba in the isochronous stream. Neural entrainment was demonstrated for all stream types, and individual differences in standardized measures of language processing were related to auditory entrainment at the theta rate. Further, there was significant modulation of the preferred phase of auditory entrainment in the theta band when visual speech cues were present, indicating cross-modal phase resetting. The rhythmic entrainment paradigm developed here offers a method for exploring individual differences in oscillatory phase locking during development. In particular, a method for assessing neural entrainment and cross-modal phase resetting would be useful for exploring developmental learning difficulties thought to involve temporal sampling

  9. Cinema Fire Modelling by FDS

    International Nuclear Information System (INIS)

    Glasa, J; Valasek, L; Weisenpacher, P; Halada, L

    2013-01-01

    Recent advances in computer fluid dynamics (CFD) and rapid increase of computational power of current computers have led to the development of CFD models capable to describe fire in complex geometries incorporating a wide variety of physical phenomena related to fire. In this paper, we demonstrate the use of Fire Dynamics Simulator (FDS) for cinema fire modelling. FDS is an advanced CFD system intended for simulation of the fire and smoke spread and prediction of thermal flows, toxic substances concentrations and other relevant parameters of fire. The course of fire in a cinema hall is described focusing on related safety risks. Fire properties of flammable materials used in the simulation were determined by laboratory measurements and validated by fire tests and computer simulations

  10. Cinema Fire Modelling by FDS

    Science.gov (United States)

    Glasa, J.; Valasek, L.; Weisenpacher, P.; Halada, L.

    2013-02-01

    Recent advances in computer fluid dynamics (CFD) and rapid increase of computational power of current computers have led to the development of CFD models capable to describe fire in complex geometries incorporating a wide variety of physical phenomena related to fire. In this paper, we demonstrate the use of Fire Dynamics Simulator (FDS) for cinema fire modelling. FDS is an advanced CFD system intended for simulation of the fire and smoke spread and prediction of thermal flows, toxic substances concentrations and other relevant parameters of fire. The course of fire in a cinema hall is described focusing on related safety risks. Fire properties of flammable materials used in the simulation were determined by laboratory measurements and validated by fire tests and computer simulations

  11. Simulating the impact of the entrainment of winter flounder larvae

    International Nuclear Information System (INIS)

    Hess, K.W.; Sissenwine, M.P.; Saila, S.B.

    1975-01-01

    The transport of winter flounder larvae around the Millstone Point, Conn. Area by the action of tidal currents and diffusion was simulated by computer to predict the numbers which could be entrained during the operation of a local nuclear power station. A tidal hydrodynamic model with variable depth was employed to simulate currents and water levels. These techniques provided input to a transport model which simulated the concentration of larvae. A larval source in a tributary river was simulated for twenty tidal cycles, with and without entrainment. The results indicated that the reduction in winter flounder larvae near Millstone Point at the end of the pelagic stage (period during which larvae are likely to be entrained) was less than 1 percent when it was assumed that larvae have little chance of returning once lost from Millstone bight. In order to assess the effect of a 1 percent reduction in recruitment of winter flounder larvae to the benthic phase of their life cycle, the local population was simulated by a model in which year-classes and the total egg production were represented by compartments. Each year-class grew, produced eggs, suffered natural and fishing mortality according to information derived from the literature. The effect of power plant entrainment was incorporated by reducing the number of recruits to year-class I that would normally result from a specific level of egg production. For a 1 percent reduction in recruitment due to power plant entrainment, a potential 6 percent decrease in total population size following 35 years of operation was indicated. (U.S.)

  12. Getting the beat: entrainment of brain activity by musical rhythm and pleasantness.

    Science.gov (United States)

    Trost, Wiebke; Frühholz, Sascha; Schön, Daniele; Labbé, Carolina; Pichon, Swann; Grandjean, Didier; Vuilleumier, Patrik

    2014-12-01

    Rhythmic entrainment is an important component of emotion induction by music, but brain circuits recruited during spontaneous entrainment of attention by music and the influence of the subjective emotional feelings evoked by music remain still largely unresolved. In this study we used fMRI to test whether the metric structure of music entrains brain activity and how music pleasantness influences such entrainment. Participants listened to piano music while performing a speeded visuomotor detection task in which targets appeared time-locked to either strong or weak beats. Each musical piece was presented in both a consonant/pleasant and dissonant/unpleasant version. Consonant music facilitated target detection and targets presented synchronously with strong beats were detected faster. FMRI showed increased activation of bilateral caudate nucleus when responding on strong beats, whereas consonance enhanced activity in attentional networks. Meter and consonance selectively interacted in the caudate nucleus, with greater meter effects during dissonant than consonant music. These results reveal that the basal ganglia, involved both in emotion and rhythm processing, critically contribute to rhythmic entrainment of subcortical brain circuits by music. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Numerical study of fire whirlwind taking into account radiative heat transfer

    Science.gov (United States)

    Sakai, S.; Miyagi, N.

    2010-06-01

    The fire whirlwind is a strong swirling flow with flame and spark, which may occur in the case of, widespread fire in the urban region by an earthquake disaster or an air raid, and a large-scale fire such as a forest fire. Fire whirlwind moves and promotes spread of fire and may extend serious damage rapidly. In this study, performing the numerical analysis of fire whirlwind with respect to scale effect, it is examined whether a relationship exists between a real phenomenon and the phenomenon in the reduction model with taking into account radiative heat transfer. Three dimensional analyses are performed to investigate the thermal and flow fields by using the analytical software FLUENT6.3. It is analyzed that those swirling flow in original scale, 1/10 scale, 1/50 scale, 1/100 scale from the original brake out to vanish. As an analytical condition, parameter calculation is repeated to get the velocity of a parallel flow which is the easiest to occur the swirling flow for each reduction model, and then scale effect is discussed by comparing the velocity of the natural convection, the velocity of the parallel flow, the center pressure of the whirlwind and the continuance time of the swirling flow. The analysis model of C-character heat source model is performed as well as the analysis in L-character model, which is one of the representative example of the fire whirlwind occurred at Tokyo in the Great Kanto Earthquake (1923). The result of the numerical analysis shows that there is a scale effect to the speed of the parallel flow to generate the swirling flow.

  14. Numerical study of fire whirlwind taking into account radiative heat transfer

    International Nuclear Information System (INIS)

    Sakai, S; Miyagi, N

    2010-01-01

    The fire whirlwind is a strong swirling flow with flame and spark, which may occur in the case of, widespread fire in the urban region by an earthquake disaster or an air raid, and a large-scale fire such as a forest fire. Fire whirlwind moves and promotes spread of fire and may extend serious damage rapidly. In this study, performing the numerical analysis of fire whirlwind with respect to scale effect, it is examined whether a relationship exists between a real phenomenon and the phenomenon in the reduction model with taking into account radiative heat transfer. Three dimensional analyses are performed to investigate the thermal and flow fields by using the analytical software FLUENT6.3. It is analyzed that those swirling flow in original scale, 1/10 scale, 1/50 scale, 1/100 scale from the original brake out to vanish. As an analytical condition, parameter calculation is repeated to get the velocity of a parallel flow which is the easiest to occur the swirling flow for each reduction model, and then scale effect is discussed by comparing the velocity of the natural convection, the velocity of the parallel flow, the center pressure of the whirlwind and the continuance time of the swirling flow. The analysis model of C-character heat source model is performed as well as the analysis in L-character model, which is one of the representative example of the fire whirlwind occurred at Tokyo in the Great Kanto Earthquake (1923). The result of the numerical analysis shows that there is a scale effect to the speed of the parallel flow to generate the swirling flow.

  15. Nonphotic entrainment in a diurnal mammal, the European ground squirrel (Spermophilus citellus)

    NARCIS (Netherlands)

    Hut, Roelof A.; Mrosovsky, N.; Daan, Serge

    1999-01-01

    Entrainment by nonphotic, activity-inducing stimuli has been investigated in detail in nocturnal rodents, but little is known about nonphotic entrainment in diurnal animals. Comparative studies would offer the opportunity to distinguish between two possibilities. (1) If nonphotic phase shifts depend

  16. Modelling, simulation, and optimisation of a downflow entrained flow reactor for black liquor gasification

    Energy Technology Data Exchange (ETDEWEB)

    Marklund, Magnus [ETC Energitekniskt Centrum, Piteaa (Sweden)

    2003-12-01

    Black liquor, a by-product of the chemical pulping process, is an important liquid fuel in the pulp and paper industry. A potential technology for improving the recovery cycle of energy and chemicals contained in the liquid fuel is pressurised gasification of black liquor (PGLG). However, uncertainties about the reliability and robustness of the technology are preventing a large-scale market introduction. One important step towards a greater trust in the process reliability is the development of simulation tools that can provide a better understanding of the process and improve performance through optimisation. In the beginning of 2001 a project was initiated in order to develop a simulation tool for an entrained-flow gasifier in PBLG based on CFD (Computational Fluid Dynamics). The aim has been to provide an advanced tool for a better understanding of process performance, to help with trouble shooting in the development plant, and for use in optimisation of a full-scale commercial gasifier. Furthermore, the project will also provide quantitative information on burner functionality through advanced laser-optical measurements by use of a Phase Doppler Anemometer (PDA). To this point in current project, three different concept models have been developed. The work has been comprised in a thesis 'Modelling and Simulation of Pressurised Black Liquor Gasification at High Temperature' and presented at Luleaa Univ. of Technology in Oct 2003. The construction of an atmospheric burner test rig has also been initiated. The main objective with the rig will be to quantify the atomisation performance of suitable burner nozzles for a PBLG gasifier that can be used as input for the CFD model. The main conclusions from the modelling work done this far can be condensed to the following points: From the first modelling results it was concluded that a wide spray pattern is preferable with respect to demand for long residence times for black liquor droplets and a low amount

  17. Speech entrainment enables patients with Broca’s aphasia to produce fluent speech

    Science.gov (United States)

    Hubbard, H. Isabel; Hudspeth, Sarah Grace; Holland, Audrey L.; Bonilha, Leonardo; Fromm, Davida; Rorden, Chris

    2012-01-01

    A distinguishing feature of Broca’s aphasia is non-fluent halting speech typically involving one to three words per utterance. Yet, despite such profound impairments, some patients can mimic audio-visual speech stimuli enabling them to produce fluent speech in real time. We call this effect ‘speech entrainment’ and reveal its neural mechanism as well as explore its usefulness as a treatment for speech production in Broca’s aphasia. In Experiment 1, 13 patients with Broca’s aphasia were tested in three conditions: (i) speech entrainment with audio-visual feedback where they attempted to mimic a speaker whose mouth was seen on an iPod screen; (ii) speech entrainment with audio-only feedback where patients mimicked heard speech; and (iii) spontaneous speech where patients spoke freely about assigned topics. The patients produced a greater variety of words using audio-visual feedback compared with audio-only feedback and spontaneous speech. No difference was found between audio-only feedback and spontaneous speech. In Experiment 2, 10 of the 13 patients included in Experiment 1 and 20 control subjects underwent functional magnetic resonance imaging to determine the neural mechanism that supports speech entrainment. Group results with patients and controls revealed greater bilateral cortical activation for speech produced during speech entrainment compared with spontaneous speech at the junction of the anterior insula and Brodmann area 47, in Brodmann area 37, and unilaterally in the left middle temporal gyrus and the dorsal portion of Broca’s area. Probabilistic white matter tracts constructed for these regions in the normal subjects revealed a structural network connected via the corpus callosum and ventral fibres through the extreme capsule. Unilateral areas were connected via the arcuate fasciculus. In Experiment 3, all patients included in Experiment 1 participated in a 6-week treatment phase using speech entrainment to improve speech production

  18. Postwildfire debris-flow hazard assessment of the area burned by the 2012 Little Bear Fire, south-central New Mexico

    Science.gov (United States)

    Tillery, Anne C.; Matherne, Anne Marie

    2013-01-01

    A preliminary hazard assessment was developed of the debris-flow potential from 56 drainage basins burned by the Little Bear Fire in south-central New Mexico in June 2012. The Little Bear Fire burned approximately 179 square kilometers (km2) (44,330 acres), including about 143 km2 (35,300 acres) of National Forest System lands of the Lincoln National Forest. Within the Lincoln National Forest, about 72 km2 (17,664 acres) of the White Mountain Wilderness were burned. The burn area also included about 34 km2 (8,500 acres) of private lands. Burn severity was high or moderate on 53 percent of the burn area. The area burned is at risk of substantial postwildfire erosion, such as that caused by debris flows and flash floods. A postwildfire debris-flow hazard assessment of the area burned by the Little Bear Fire was performed by the U.S. Geological Survey in cooperation with the U.S. Department of Agriculture Forest Service, Lincoln National Forest. A set of two empirical hazard-assessment models developed by using data from recently burned drainage basins throughout the intermountain Western United States was used to estimate the probability of debris-flow occurrence and volume of debris flows along the burn area drainage network and for selected drainage basins within the burn area. The models incorporate measures of areal burn extent and severity, topography, soils, and storm rainfall intensity to estimate the probability and volume of debris flows following the fire. Relative hazard rankings of postwildfire debris flows were produced by summing the estimated probability and volume ranking to illustrate those areas with the highest potential occurrence of debris flows with the largest volumes. The probability that a drainage basin could produce debris flows and the volume of a possible debris flow at the basin outlet were estimated for three design storms: (1) a 2-year-recurrence, 30-minute-duration rainfall of 27 millimeters (mm) (a 50 percent chance of occurrence in

  19. Evaluation of the potential for debris and hyperconcentrated flows in Capulin Canyon as a result of the 1996 Dome fire, Bandelier National Monument, New Mexico

    Science.gov (United States)

    Cannon, Susan H.

    1997-01-01

    The Dome fire of April 1996 burned 6684 ha in Bandelier National Monument and the adjacent Sante Fe National Forest. The potential for significant debris- and hyperconcentrated-flow activity in Capulin Canyon is evaluated through 1) a systematic consideration of geologic and geomorphic factors that characterize the condition of the hillslope materials and channels following the fire, 2) examination of sedimentologic evidence for past debris-flow activity in the canyon, and 3) evaluation of the response of the watershed through the 1996 summer monsoon season. The lack of accumulations of dry-ravel material on the hillslopes or in channels, the absence of a continuous hydrophobic layer, the relatively intact condition of the riparian vegetation and of the fibrous root mat on the hillslopes, and the lack of evidence of widespread past debris- and hyperconcentrated-flow activity, even with evidence of past fires, indicate a low potential for debris-flow activity in Capulin Canyon. In addition, thunderstorms during the summer monsoon of 1996 resulted in abundant surface overland flow on the hillslopes which transported low-density pumice, charcoal, ash and some mineral soil downslope as small-scale and non-erosive debris flows. In some places cobble- and boulder-sized material was moved short distances. A moderate potential for debris- and hyperconcentrated-flow activity is identified for the two major tributary canyons to Capulin Canyon based on evidence of both summer of 1996 and possible historic significant debris-flow activity.

  20. Investigation of Two-Phase Flow Regime Maps for Development of Thermal-Hydraulic Analysis Codes

    International Nuclear Information System (INIS)

    Kim, Kyung Doo; Kim, Byoung Jae; Lee, Seong Wook

    2010-04-01

    This reports is a literature survey on models and correlations for determining flow pattern that are used to simulate thermal-hydraulics in nuclear reactors. Determination of flow patterns are a basis for obtaining physical values of wall/interfacial friction, wall/interfacial heat transfer, and droplet entrainment/de-entrainment. Not only existing system codes, such as RELAP5-3D, TRAC-M, MARS, TRACE, CATHARE) but also up-to-date researches were reviewed to find models and correlations

  1. Efficiency of brainwave entrainment by binaural beats in reducing anxiety

    Directory of Open Access Journals (Sweden)

    Ahmad Alipoor

    2014-04-01

    Full Text Available Background: Anxiety is a fundamental phenomenon that is a common symptom in all mental disorders. The aim of the present study was to assess the effect of brainwave entrainment on anxiety reduction using binaural beats. Methods: In this experimental double-blind study, 30 employees were selected from an engineering research firm through random sampling and replacement and divided into two groups: control group and experimental group. All participants completed the Spielberger’s State-Trait Anxiety Inventory (STAI. Then, the experimental group listened to binaural beats which was recorded on a non-vocal piece of music for 4 weeks, 3 sessions each week. Each session lasted about 20 minutes. At the same time, the control group listened to the background music without any entrainment sound. At the end, both groups completed the anxiety questionnaire and the anxiety scores of both groups obtained before and after intervention were analyzed by ANCOVA. Results: The findings showed that the brainwave entrainment using binaural beats led to the significant reduction of state anxiety (P<0.001 and trait anxiety (P<0.018. Conclusion: Brainwave entrainment using binaural beats is an effective factor in decreasing state and trait anxiety; so, it can be used to reduce anxiety in mental health centers.

  2. Air entrainment by plunging water jets

    NARCIS (Netherlands)

    Van de Sande, E.

    1974-01-01

    Gas entrainment caused by the impact of liquid jets upon liquid pool surfaces is a subject which has received too little attention. This well-known phenomenon,which occurs In nature and in numerous industrial operations, has only recently received interest from scientific workers. The influence on

  3. The sodium fire tests performed in the FAUNA facility on up to 12m2 fire areas

    International Nuclear Information System (INIS)

    Cherdron, W.; Jordan, S.

    1983-08-01

    The FAUNA test facility started operation in 1979. It serves to investigate large area sodium fires in closed containments and to study the generation, behaviour and removal of sodium fire aerosols. In this report, the experimental results of the 6 sodium pool fires are described which were performed with up to 500 kg of sodium in fire pans of 2 m 2 , 5 m 2 and 12 m 2 surface area, respectively. Both, the thermodynamic data and the data of the reaction kinetics of the fires were determined. In addition, the behaviour of the released aerosols during and after the fire was studied. On the basis of measurements of the temperature profiles at various levels above the fire areas it was shown that the convective flows above fire areas of different sizes in closed containments differ markedly and, obviously, exert an influence on the development of the fire and the release of particles. Whilst in rather small fires the gas above the pan rises as in a chimney and flows back on the walls, no chimney effect can be observed in a large pool fire. In rather large fires higher burning rates and aerosol release rates were observed. Some meters above the fire area temperatures around 300-400 0 C, temporarily even up to 700 0 C, were measured. The tests F5 and F6 were performed above all to observe the fire behaviour in terms of thermodynamics and reaction kinetics in a fully closed containment. (orig./RW) [de

  4. Uncertainty associated with convective wet removal of entrained aerosols in a global climate model

    Directory of Open Access Journals (Sweden)

    B. Croft

    2012-11-01

    Full Text Available The uncertainties associated with the wet removal of aerosols entrained above convective cloud bases are investigated in a global aerosol-climate model (ECHAM5-HAM under a set of limiting assumptions for the wet removal of the entrained aerosols. The limiting assumptions for the wet removal of entrained aerosols are negligible scavenging and vigorous scavenging (either through activation, with size-dependent impaction scavenging, or with the prescribed fractions of the standard model. To facilitate this process-based study, an explicit representation of cloud-droplet-borne and ice-crystal-borne aerosol mass and number, for the purpose of wet removal, is introduced into the ECHAM5-HAM model. This replaces and is compared with the prescribed cloud-droplet-borne and ice-crystal-borne aerosol fraction scavenging scheme of the standard model.

    A 20% to 35% uncertainty in simulated global, annual mean aerosol mass burdens and optical depth (AOD is attributed to different assumptions for the wet removal of aerosols entrained above convective cloud bases. Assumptions about the removal of aerosols entrained above convective cloud bases control modeled upper tropospheric aerosol concentrations by as much as one order of magnitude.

    Simulated aerosols entrained above convective cloud bases contribute 20% to 50% of modeled global, annual mean aerosol mass convective wet deposition (about 5% to 10% of the total dry and wet deposition, depending on the aerosol species, when including wet scavenging of those entrained aerosols (either by activation, size-dependent impaction, or with the prescribed fraction scheme. Among the simulations, the prescribed fraction and size-dependent impaction schemes yield the largest global, annual mean aerosol mass convective wet deposition (by about two-fold. However, the prescribed fraction scheme has more vigorous convective mixed-phase wet removal (by two to five-fold relative to the size-dependent impaction

  5. Uncertainty associated with convective wet removal of entrained aerosols in a global climate model

    Science.gov (United States)

    Croft, B.; Pierce, J. R.; Martin, R. V.; Hoose, C.; Lohmann, U.

    2012-11-01

    The uncertainties associated with the wet removal of aerosols entrained above convective cloud bases are investigated in a global aerosol-climate model (ECHAM5-HAM) under a set of limiting assumptions for the wet removal of the entrained aerosols. The limiting assumptions for the wet removal of entrained aerosols are negligible scavenging and vigorous scavenging (either through activation, with size-dependent impaction scavenging, or with the prescribed fractions of the standard model). To facilitate this process-based study, an explicit representation of cloud-droplet-borne and ice-crystal-borne aerosol mass and number, for the purpose of wet removal, is introduced into the ECHAM5-HAM model. This replaces and is compared with the prescribed cloud-droplet-borne and ice-crystal-borne aerosol fraction scavenging scheme of the standard model. A 20% to 35% uncertainty in simulated global, annual mean aerosol mass burdens and optical depth (AOD) is attributed to different assumptions for the wet removal of aerosols entrained above convective cloud bases. Assumptions about the removal of aerosols entrained above convective cloud bases control modeled upper tropospheric aerosol concentrations by as much as one order of magnitude. Simulated aerosols entrained above convective cloud bases contribute 20% to 50% of modeled global, annual mean aerosol mass convective wet deposition (about 5% to 10% of the total dry and wet deposition), depending on the aerosol species, when including wet scavenging of those entrained aerosols (either by activation, size-dependent impaction, or with the prescribed fraction scheme). Among the simulations, the prescribed fraction and size-dependent impaction schemes yield the largest global, annual mean aerosol mass convective wet deposition (by about two-fold). However, the prescribed fraction scheme has more vigorous convective mixed-phase wet removal (by two to five-fold relative to the size-dependent impaction scheme) since nearly all

  6. AW-101 entrained solids - Solubility versus temperature

    International Nuclear Information System (INIS)

    GJ Lumetta; RC Lettau; GF Piepel

    2000-01-01

    This report describes the results of a test conducted by Battelle to assess the solubility of the solids entrained in the diluted AW-101 low-activity waste (LAW) sample. BNFL requested Battelle to dilute the AW-1-1 sample using de-ionized water to mimic expected plant operating conditions. BNFL further requested Battelle to assess the solubility of the solids present in the diluted AW-101 sample versus temperature conditions of 30, 40, and 50 C. BNFL requested these tests to assess the composition of the LAW supernatant and solids versus expected plant-operating conditions. The work was conducted according to test plan BNFL-TP-29953-7, Rev. 0, Determination of the Solubility of LAW Entrained Solids. The test went according to plan, with no deviations from the test plan

  7. Surf zone entrainment, along-shore transport, and human health implications of pollution from tidal outlets

    Science.gov (United States)

    Grant, S. B.; Kim, J. H.; Jones, B. H.; Jenkins, S. A.; Wasyl, J.; Cudaback, C.

    2005-10-01

    Field experiments and modeling studies were carried out to characterize the surf zone entrainment and along-shore transport of pollution from two tidal outlets that drain into Huntington Beach and Newport Beach, popular public beaches in southern California. The surf zone entrainment and near-shore transport of pollutants from these tidal outlets appears to be controlled by prevailing wave conditions and coastal currents, and fine-scale features of the flow field around the outlets. An analysis of data from dye experiments and fecal indicator bacteria monitoring studies reveals that the along-shore flux of surf zone water is at least 50 to 300 times larger than the cross-shore flux of surf zone water. As a result, pollutants entrained in the surf zone hug the shore, where they travel significant distances parallel to the beach before diluting to extinction. Under the assumption that all surf zone pollution at Huntington Beach originates from two tidal outlets, the Santa Ana River and Talbert Marsh outlets, models of mass and momentum transport in the surf zone approximately capture the observed tidal phasing and magnitude of certain fecal indicator bacteria groups (total coliform) but not others (Escherichia coli and enterococci), implying the existence of multiple sources of, and/or multiple transport pathways for, fecal pollution at this site. The intersection of human recreation and near-shore pollution pathways implies that, from a human health perspective, special care should be taken to reduce the discharge of harmful pollutants from land-side sources of surface water runoff, such as tidal outlets and storm drains.

  8. Watershed wash-off of atmospherically deposited radionuclides: a review of normalized entrainment coefficients

    International Nuclear Information System (INIS)

    Garcia-Sanchez, L.; Konoplev, A.V.

    2009-01-01

    Radionuclide wash-off is the transport of activity by flowing water over the soil surface (runoff). To complete existing reviews on long-term removal rates, this paper focuses on short-term wash-off fluxes, quantified in the literature by soil-runoff transfer factors called normalized liquid and solid entrainment coefficients (noted K l *, K s *). Compiled data concerned essentially 137 Cs and 90 Sr wash-off measured under simulated rainfalls on small experimental plots after Chernobyl fallout in the exclusion zone. K l * and K s * values span approximately one order of magnitude. Their validity is limited to a season, and their representativeness is limited by restricted studied situations, notably dominant unsoluble forms in fallout, light soils and intense rainfalls. Formulas based on a simplified representation of the soil-runoff system were proposed to generalize the existing values for other conditions. However, their implementation requires a more systematic compilation of the available information, including decisive influence factors such as the fraction of exchangeable form, distribution coefficient, suspended matter enrichment ratio. Entrainment coefficients K l * and K s * were mathematically related to the transfer function approach. The proposed relationships proved their complementarity in terms of time support and captured fluctuations. Both approaches should be used in assessments to estimate average fluxes and their variability.

  9. Numerical modeling of the effects of fire-induced convection and fire-atmosphere interactions on wildfire spread and fire plume dynamics

    Science.gov (United States)

    Sun, Ruiyu

    It is possible due to present day computing power to produce a fluid dynamical physically-based numerical solution to wildfire behavior, at least in the research mode. This type of wildfire modeling affords a flexibility and produces details that are not available in either current operational wildfire behavior models or field experiments. However before using these models to study wildfire, validation is necessary, and model results need to be systematically and objectively analyzed and compared to real fires. Plume theory and data from the Meteotron experiment, which was specially designed to provide results from measurements for the theoretical study of a convective plume produced by a high heat source at the ground, are used here to evaluate the fire plume properties simulated by two numerical wildfire models, the Fire Dynamics Simulator or FDS, and the Clark coupled atmosphere-fire model. The study indicates that the FDS produces good agreement with the plume theory and the Meteotron results. The study also suggests that the coupled atmosphere-fire model, a less explicit and ideally less computationally demanding model than the FDS; can produce good agreement, but that the agreement is sensitive to the method of putting the energy released from the fire into the atmosphere. The WFDS (Wildfire and wildland-urban interface FDS), an extension of the FDS to the vegetative fuel, and the Australian grass fire experiments are used to evaluate and improve the UULES-wildfire coupled model. Despite the simple fire parameterization in the UULES-wildfire coupled model, the fireline is fairly well predicted in terms of both shape and location in the simulation of Australian grass fire experiment F19. Finally, the UULES-wildfire coupled model is used to examine how the turbulent flow in the atmospheric boundary layer (ABL) affects the growth of the grass fires. The model fires showed significant randomness in fire growth: Fire spread is not deterministic in the ABL, and a

  10. Characterisation of vortex flow inside an entrained cavity

    Energy Technology Data Exchange (ETDEWEB)

    Rambert, A.; Elcafsi, A.; Gougat, P. [Centre National de la Recherche Scientifique, 91 - Orsay (France). Lab. d' Informatique pour la Mecanique et les Sciences de l' Ingenieur

    2000-07-01

    A number of studies have referred to the existence of a vortex cell within an urban street canyon when ambient winds aloft are perpendicular to the street. The understanding of vortex dynamics or vorticity distribution in a such configuration is of great interest. Vortex structures play an important role in the dynamics of pollutant dispersion. This configuration was simulated by the interaction between a boundary layer and a cavity. Experimental characterisation of the vortex structures evolution was developed by flow velocity measurements inside and out of the cavity. Classical methods like hot wire and laser Doppler velocimetry (LDV) display only local measurements. Particle image velocimetry (PIV) method based on the optical flow technique permitted global velocity measurements. This technique emphasis the vortex structures inside the cavity which present small scales as well as large scales related to the cavity geometry. These vortices are usually non-stationary. (orig.)

  11. Effect of fast freeze-thaw cycles on mechanical properties of ordinary-air-entrained concrete.

    Science.gov (United States)

    Shang, Huai-shuai; Cao, Wei-qun; Wang, Bin

    2014-01-01

    Freezing-thawing resistance is a very significant characteristic for concrete in severe environment (such as cold region with the lowest temperature below 0°C). In this study, ordinary-air-entrained (O-A-E) concrete was produced in a laboratory environment; the compressive strength, cubic compressive strength of C50, C40, C30, C25, and C20 ordinary-air-entrained concrete, tensile strength, and cleavage strength of C30 ordinary-air-entrained concrete were measured after fast freeze-thaw cycles. The effects of fast freeze-thaw cycles on the mechanical properties (compressive strength and cleavage strength) of ordinary-air-entrained concrete materials are investigated on the basis of the experimental results. And the concise mathematical formula between mechanical behavior and number of fast freeze-thaw cycles was established. The experiment results can be used as a reference in design, maintenance, and life prediction of ordinary-air-entrained concrete structure (such as dam, offshore platform, etc.) in cold regions.

  12. Effect of oxy-fuel combustion with steam addition on coal ignition and burnout in an entrained flow reactor

    International Nuclear Information System (INIS)

    Riaza, J.; Alvarez, L.; Gil, M.V.; Pevida, C.; Pis, J.J.; Rubiera, F.

    2011-01-01

    The ignition temperature and burnout of a semi-anthracite and a high-volatile bituminous coal were studied under oxy-fuel combustion conditions in an entrained flow reactor (EFR). The results obtained under oxy-fuel atmospheres (21%O 2 -79%CO 2 , 30%O 2 -70% O 2 and 35%O 2 -65%CO 2 ) were compared with those attained in air. The replacement of CO 2 by 5, 10 and 20% of steam in the oxy-fuel combustion atmospheres was also evaluated in order to study the wet recirculation of flue gas. For the 21%O 2 -79%CO 2 atmosphere, the results indicated that the ignition temperature was higher and the coal burnout was lower than in air. However, when the O 2 concentration was increased to 30 and 35% in the oxy-fuel combustion atmosphere, the ignition temperature was lower and coal burnout was improved in comparison with air conditions. On the other hand, an increase in ignition temperature and a worsening of the coal burnout was observed when steam was added to the oxy-fuel combustion atmospheres though no relevant differences between the different steam concentrations were detected. -- Highlights: → The ignition temperature and the burnout of two thermal coals under oxy-fuel combustion conditions were determined. → The effect of the wet recirculation of flue gas on combustion behaviour was evaluated. → Addition of steam caused a worsening of the ignition temperature and coal burnout.

  13. Entrainment of ichthyoplankton and larval fishes during cooling water withdrawal

    International Nuclear Information System (INIS)

    McFarlane, R.W.

    1978-01-01

    Plantonic fish eggs and larvae are entrained into the Savannah River Plant (SRP) pumping system as Savannah River water is withdrawn for cooling purposes. The American shad contributed 96% of the planktonic fish eggs collected in the Savannah River. Eggs were rare in plankton samples from the intake canals and were assumed to have settled to the bottom as current velocity was reduced in the canal entrance. An estimated 72 million fish eggs were transported past the intake canals. Assuming ''worst case conditions,'' 6.8 million eggs (9.5%) could have been lost due to entrainment. Blueback herring comprised nearly one-half of the 216 million fish larvae susceptible to impact. Spotted sucker and black crappie were also common among the 22 species of fish larvae collected. An estimated 19.6 million (9.1%) fish larvae could have been entrained under ''worst case conditions''

  14. Two-phase interactions in countercurrent flow studies of the flooding mechanism. Progress report 1 Nov 1975--30 Sep 1976

    International Nuclear Information System (INIS)

    Dukler, A.E.; Smith, L.

    1977-06-01

    During a loss of coolant accident in a pressurized water reactor countercurrent flow, flooding and upflow are all expected to take place. Predicting the transition from counter to upflow requires a reliable model for the flooding process. The first phase of a study is reported here which has the objective of evolving the mechanism for the flow reversal process and of developing sound productive models. This report includes a description of the experimental test loop constructed and the experimental measurements made during the first eleven months of the project. Measurements were made of liquid flowing downward as a film as well as upflow in the film entrained droplets as the system was carried through flow reversal. Time variation of pressure and pressure gradients were measured at four stations along the axis. The measurements demonstrated that the onset of flooding was associated with the onset of entrainment and that wave closure and blocking did not occur. Two types of flooding were observed. When entrainment takes place at the point of liquid entry, then flooding is characterized by a slugging or churning. When entrainment initiates well below the entry, then flow reversal occurs by droplet transport above the feed. Criteria for the existence of these two types of flooding are proposed

  15. A hybrid model to predict the entrainment and subsurface transport of oil

    International Nuclear Information System (INIS)

    Spaulding, M.L.; Odulo, A.; Kolluru, V.S.

    1992-01-01

    The entrainment of surface oil into the water column and its subsequent subsurface transport and dispersion are predicted by a hybrid analytic-numerical solution to the advective diffusion equation. Total oil or selected hydrocarbon component concentrations in the water column are predicted. Assuming that the principal mechanism for entrainment is due to breaking waves, the oil entrainment rate is specified using the empirically based algorithm of Delvigne and Sweeney (1988). The subsurface transport model explicitly accounts for buoyant forces on dispersed oil by droplet size. Application of the model to an analytic test case and several hypothetical scenarios illustrates the model's utility. 35 refs., 8 figs., 2 tabs

  16. Cortical oscillations and entrainment in speech processing during working memory load.

    Science.gov (United States)

    Hjortkjaer, Jens; Märcher-Rørsted, Jonatan; Fuglsang, Søren A; Dau, Torsten

    2018-02-02

    Neuronal oscillations are thought to play an important role in working memory (WM) and speech processing. Listening to speech in real-life situations is often cognitively demanding but it is unknown whether WM load influences how auditory cortical activity synchronizes to speech features. Here, we developed an auditory n-back paradigm to investigate cortical entrainment to speech envelope fluctuations under different degrees of WM load. We measured the electroencephalogram, pupil dilations and behavioural performance from 22 subjects listening to continuous speech with an embedded n-back task. The speech stimuli consisted of long spoken number sequences created to match natural speech in terms of sentence intonation, syllabic rate and phonetic content. To burden different WM functions during speech processing, listeners performed an n-back task on the speech sequences in different levels of background noise. Increasing WM load at higher n-back levels was associated with a decrease in posterior alpha power as well as increased pupil dilations. Frontal theta power increased at the start of the trial and increased additionally with higher n-back level. The observed alpha-theta power changes are consistent with visual n-back paradigms suggesting general oscillatory correlates of WM processing load. Speech entrainment was measured as a linear mapping between the envelope of the speech signal and low-frequency cortical activity (level) decreased cortical speech envelope entrainment. Although entrainment persisted under high load, our results suggest a top-down influence of WM processing on cortical speech entrainment. © 2018 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  17. Measurements on Buoyant Jet Flows from a Ceiling-Mounted Slot Diffuser

    DEFF Research Database (Denmark)

    Nielsen, Peter V.; Möller, Åke T. A.

    Ceiling-mounted slot diffusers in ventilated rooms will often generate a flow of the wall jet type. The jet follows the ceiling, entrains air from the occupied zone and generates a recirculating flow in the whole room. This paper will deal with the flow in the ceiling region. The wall jet flow...

  18. Estimates of entrainment mortality for striped bass and other fish species inhabiting the Hudson River estuary

    International Nuclear Information System (INIS)

    Boreman, J.; Goodyear, C.P.

    1988-01-01

    An empirically derived age-, time-, and space-variant equation was used to estimate entrainment mortality at power plants for seven fish species inhabiting the Hudson River estuary. Entrainment mortality is expressed as a conditional rate, which is the fractional reduction in year-class strength due to entrainment if other sources of mortality are density-independent. Estimates of the conditional entrainment mortality, based on historical and projected once-through cooling operation of five power plants, were 11-22% for striped bass, 11-17% for white perch, 5-7% for Atlantic tomcod, 14-21% for American shad, 4-11% for river herring (alewife and blueback herring combined), and 35-79% for bay anchovy. Closed-cycle cooling (natural-draft cooling towers) at three of the power plants (Indian Point, Bowline Point, and Roseton) would reduce entrainment mortality of striped bass by 50-80%, of white perch by 75-80%, of Atlantic tocod by 65-70%, of American shad by 80%, of river herring by 30-90%, and of bay anchovy by 45-80%. The life stages most vulnerable to entrainment mortality were post-yolk-sac larva and entrainable size juvenile. 18 refs., 7 tabs

  19. Characterization of Oxy-combustion Impacts in Existing Coal-fired Boilers

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Bradley [Univ. of Utah, Salt Lake City, UT (United States); Davis, Kevin [Univ. of Utah, Salt Lake City, UT (United States); Senior, Constance [Univ. of Utah, Salt Lake City, UT (United States); Shim, Hong Shim [Univ. of Utah, Salt Lake City, UT (United States); Otten, Brydger Van [Univ. of Utah, Salt Lake City, UT (United States); Fry, Andrew [Univ. of Utah, Salt Lake City, UT (United States); Wendt, Jost [Univ. of Utah, Salt Lake City, UT (United States); Eddings, Eric [Univ. of Utah, Salt Lake City, UT (United States); Paschedag, Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Shaddix, Christopher [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cox, William [Brigham Young Univ., Provo, UT (United States); Tree, Dale [Brigham Young Univ., Provo, UT (United States)

    2013-09-30

    Reaction Engineering International (REI) managed a team of experts from University of Utah, Siemens Energy, Praxair, Vattenfall AB, Sandia National Laboratories, Brigham Young University (BYU) and Corrosion Management Ltd. to perform multi-scale experiments, coupled with mechanism development, process modeling and CFD modeling, for both applied and fundamental investigations. The primary objective of this program was to acquire data and develop tools to characterize and predict impacts of CO{sub 2} flue gas recycle and burner feed design on flame characteristics (burnout, NO{sub x}, SO{sub x}, mercury and fine particle emissions, heat transfer) and operational concerns (fouling, slagging and corrosion) inherent in the retrofit of existing coal-fired boilers for oxy-coal combustion. Experimental work was conducted at Sandia National Laboratories’ Entrained Flow Reactor, the University of Utah Industrial Combustion Research Facility, and Brigham Young University. Process modeling and computational fluid dynamics (CFD) modeling was performed at REI. Successful completion of the project objectives resulted in the following key deliverables: 1) Multi-scale test data from 0.1 kW bench-scale, 100 kW and 200 kW laboratory-scale, and 1 MW semi-industrial scale combustors that describe differences in flame characteristics, fouling, slagging and corrosion for coal combustion under air-firing and oxygen-firing conditions, including sensitivity to oxy-burner design and flue gas recycle composition. 2) Validated mechanisms developed from test data that describe fouling, slagging, waterwall corrosion, heat transfer, char burnout and sooting under coal oxy-combustion conditions. The mechanisms were presented in a form suitable for inclusion in CFD models or process models. 3) Principles to guide design of pilot-scale and full-scale coal oxy-firing systems and flue gas recycle configurations, such that boiler operational impacts from oxy-combustion retrofits are minimized. 4

  20. One-dimensional three-field model of condensation in horizontal countercurrent flow with supercritical liquid velocity

    International Nuclear Information System (INIS)

    Trewin, Richard R.

    2011-01-01

    Highlights: → CCFL in the hot leg of a PWR with ECC Injection. → Three-Field Model of counter flowing water film and entrained droplets. → Flow of steam can cause a hydraulic jump in the supercritical flow of water. → Condensation of steam on subcooled water increases the required flow for hydraulic jump. → Better agreement with UPTF experimental data than Wallis-type correlation. - Abstract: A one-dimensional three-field model was developed to predict the flow of liquid and vapor that results from countercurrent flow of water injected into the hot leg of a PWR and the oncoming steam flowing from the upper plenum. The model solves the conservation equations for mass, momentum, and energy in a continuous-vapor field, a continuous-liquid field, and a dispersed-liquid (entrained-droplet) field. Single-effect experiments performed in the upper plenum test facility (UPTF) of the former SIEMENS KWU (now AREVA) at Mannheim, Germany, were used to validate the countercurrent flow limitation (CCFL) model in case of emergency core cooling water injection into the hot legs. Subcooled water and saturated steam flowed countercurrent in a horizontal pipe with an inside diameter of 0.75 m. The flow of injected water was varied from 150 kg/s to 400 kg/s, and the flow of steam varied from 13 kg/s to 178 kg/s. The subcooling of the liquid ranged from 0 K to 104 K. The velocity of the water at the injection point was supercritical (greater than the celerity of a gravity wave) for all the experiments. The three-field model was successfully used to predict the experimental data, and the results from the model provide insight into the mechanisms that influence the flows of liquid and vapor during countercurrent flow in a hot leg. When the injected water was saturated and the flow of steam was small, all or most of the injected water flowed to the upper plenum. Because the velocity of the liquid remained supercritical, entrainment of droplets was suppressed. When the injected

  1. Non-slag co-gasification of biomass and coal in entrained-bed furnace

    Science.gov (United States)

    Itaya, Yoshinori; Suami, Akira; Kobayashi, Nobusuke

    2018-02-01

    Gasification is a promising candidate of processes to upgrade biomass and to yield clean gaseous fuel for utilization of renewable energy resources. However, a sufficient amount of biomass is not always available to operate a large scale of the plant. Co-gasification of biomass with coal is proposed as a solution of the problem. Tar emission is another subject during operation in shaft or kiln type of gasifiers employed conventionally for biomass. The present authors proposed co-gasification of biomass and coal in entrained-bed furnace, which is a representative process without tar emission under high temperature, but operated so to collect dust as flyash without molten slag formation. This paper presents the works performed on co-gasification performance of biomass and pulverized coal to apply to entrained-bed type of furnaces. At first, co-gasification of woody powder and pulverized coal examined using the lab-scale test furnace of the down-flow entrained bed showed that the maximum temperatures in the furnace was over 1500 K and the carbon conversion to gas achieved at higher efficiency than 80-90 percent although the residence time in the furnace was as short as a few seconds. Non-slag co-gasification was carried out successfully without slag formation in the furnace if coal containing ash with high fusion temperature was employed. The trend suggesting the effect of reaction rate enhancement of co-gasification was also observed. Secondary, an innovative sewage sludge upgrading system consisting of self-energy recovery processes was proposed to yield bio-dried sludge and to sequentially produce char without adding auxiliary fuel. Carbonization behavior of bio-dried sludge was evaluated through pyrolysis examination in a lab-scale quartz tube reactor. The thermal treatment of pyrolysis of sludge contributed to decomposition and removal of contaminant components such as nitrogen and sulfur. The gasification kinetics of sludge and coal was also determined by a

  2. A numerical modeling investigation of erosion and debris flows following the 2016 Fish Fire in the San Gabriel Mountains, CA, USA

    Science.gov (United States)

    Tang, H.; McGuire, L.; Rengers, F. K.; Kean, J. W.; Staley, D. M.

    2017-12-01

    Wildfire significantly changes the hydrological characteristics of soil for a period of several years and increases the likelihood of flooding and debris flows during high-intensity rainfall in steep watersheds. Hazards related to post-fire flooding and debris flows increase as populations expand into mountainous areas that are susceptible to wildfire, post-wildfire flooding, and debris flows. However, our understanding of post-wildfire debris flows is limited due to a paucity of direct observations and measurements, partially due to the remote locations where debris flows tend to initiate. In these situations, numerical modeling becomes a very useful tool for studying post-wildfire debris flows. Research based on numerical modeling improves our understanding of the physical mechanisms responsible for the increase in erosion and consequent formation of debris flows in burned areas. In this contribution, we study changes in sediment transport efficiency with time since burning by combining terrestrial laser scanning (TLS) surveys of a hillslope burned during the 2016 Fish Fire with numerical modeling of overland flow and sediment transport. We also combine the numerical model with measurements of debris flow timing to explore relationships between post-wildfire rainfall characteristics, soil infiltration capacity, hillslope erosion, and debris flow initiation at the drainage basin scale. Field data show that an initial rill network developed on the hillslope, and became more efficient over time as the overall rill density decreased. Preliminary model results suggest that this can be achieved when flow driven detachment mechanisms dominate and raindrop-driven detachment is minimized. Results also provide insight into the hydrologic and geomorphic conditions that lead to debris flow initiation within recently burned areas.

  3. Warm Water Entrainment Impacts and Environmental Life Cycle Assessment of a Proposed Ocean Thermal Energy Conversion Pilot Plant Offshore Oahu, Hawaii

    Science.gov (United States)

    Hauer, Whitney Blanchard

    Ocean thermal energy conversion (OTEC) is a marine renewable energy technology that uses the temperature difference of large volumes of cold deep and warm surface seawater in tropical regions to generate electricity. One anticipated environmental impact of OTEC operations is the entrainment and subsequent mortality of ichthyoplankton (fish eggs and larvae) from the withdrawal of cold and warm seawater. The potential ichthyoplankton loss from the warm water intake was estimated for a proposed 10 MW OTEC pilot plant offshore Oahu, HI based on ambient vertical distribution data. The estimated losses due to entrainment from the warm water intake were 8.418E+02 larvae/1000 m3, 3.26E+06 larvae/day, and 1.19E+09 larvae/year. The potential entrained larvae/year is 1.86 X greater than at the Kahe Generating Station (Kapolei, HI), a 582 MW oil-fired power plant. Extrapolating to age-1 equivalence (9.2E+02 and 2.9E+02 yellowfin and skipjack tuna, respectively), the estimated yearly losses from warm water entrainment of yellowfin and skipjack tuna fish eggs and larvae represent 0.25-0.26 % and 0.09-0.11 % of Hawaii's commercial yellowfin and skipjack tuna industry in 2011 and 2012. An environmental life cycle assessment (LCA) was developed for the proposed OTEC plant operating for 20 and 40 years with availability factors of 0.85, 0.95, and 1.0 to determine the global warming potential (GWP) and cumulative energy demand (CED) impacts. For a 20 year operational OTEC plant, the GWP, CED, energy return on investment (EROI), and energy payback time (EPBT) ranged from 0.047 to 0.055 kg CO2eq/kWh, 0.678 to 0.798 MJ/kWh, 4.51 to 5.31 (unitless), and 3.77 to 4.43 years, respectively. For a 40 year operational OTEC plant, the GWP, CED, EROI, and EBPT ranged from 0.036 to 0.043 kg CO2eq/kWh, 0.527 to 0.620 MJ/kWh, 5.81 to 6.83 (unitless), and 5.85 to 6.89 years, respectively. The GWP impacts are within the range of renewable energy technologies and less than conventional electricity

  4. The effects of arbitrary injection angle and flow conditions on venturi-jet mixer

    Directory of Open Access Journals (Sweden)

    Sundararaj S.

    2012-01-01

    Full Text Available This paper describes the effect of jet injection angle, cross flow Reynolds number and velocity ratio on entrainment and mixing of jet with incompressible cross flow in venturi-jet mixer. Five different jet injection angles 45o, 60o, 90o, 125o, 135o are tested to evaluate the entrainment of jet and mixing performances of the mixer. Tracer concentration along the downstream of the jet injection, cross flow velocity, jet velocity and pressure drop across the mixer are determined experimentally to characterize the mixing performance of the mixer. The experiments show that the performance of a venturi-jet-mixer substantially improves at high injection angle and can be augmented still by increasing velocity ratio. The jet deflects much and penetrates less in the cross flow as the cross flow Reynolds number is increased. The effect could contribute substantially to the better mixing index with moderate pressure drop. Normalized jet profile, concentration decay, jet velocity profile are computed from equations of conservation of mass, momentum and concentration written in natural co-ordinate systems. The comparison between the experimental and numerical results confirms the accuracy of the simulations. Correlations for jet trajectory and entrainment ratio of the mixer are obtained by multivariate-linear regression analysis using power law.

  5. Project 93L-EWL-097, fire alarm system improvements, 300 Area

    International Nuclear Information System (INIS)

    Scott, M.V.

    1995-01-01

    This document contains the Acceptance Test Procedure (ATP) which will demonstrate that the modifications to the Fire Protection systems in the 338 Building function as intended. The ATP will test the fire alarm control panel, flow alarm pressure switch, post indicator valve tamper switch, heat detectors, flow switches, and fire alarm signaling devices

  6. Liquid entrainment and off-take through the break at the top of a vessel

    International Nuclear Information System (INIS)

    Kim, Chang Hyun; No, Hee Cheon

    2005-01-01

    In order to determine the bleed capacity of the safety depressurization system (SDS) of Advanced Power Reactor 1400 (APR1400) in the case of total loss of feed water (TLOFW), we performed an experimental study of liquid entrainment and liquid off-take from the swelled two-phase mixture surface in a vessel. A total of 220 experimental data on the entrainment and off-take are obtained using a test vessel with a height of 2.0m and an inner diameter of 0.3m and a top break with a diameter of 0.05m. Two-phase mixture levels are measured by an ultrasonic sensor within +/-1.77% with respect to the visual level data. Droplet entrainment data are obtained with and without the top break and are compared with the existing pool entrainment data. The present droplet entrainment data have higher values than the existing pool entrainment data due to (a) the pulling toward the break of the liquid deentrained on the top wall of the vessel and (b) gas acceleration in the vicinity of the break. In the present experiment, droplet entrainment, E fg , strongly depends upon j g * /h * and is proportional to the seventh power of j g * /h * in the same way as the off-take data. The empirical correlation for the onset of off-take is developed in terms of the Froude number (Fr g ) at the break and the non-dimensional inception height (h b /d). This correlation shows agreement with the present experimental data within +/-15%. The present off-take quality data show agreement with Schrock's off-take quality correlation with the rms error of 15.8%

  7. Liquid entrainment and off-take from the two-phase mixture surface in a vessel

    International Nuclear Information System (INIS)

    Kim, Chang Hyun; No, Hee Cheon

    2003-01-01

    In order to determine the bleed capacity of the Safety Depressurization System (SDS) of Advanced Power Reactor 1400 (APR1400) in the case of Total Loss of Feed Water (TLOFW), we performed an experimental study of liquid entrainment and liquid off-take from the swelled two-phase mixture surface in a vessel. A total of 220 experimental data on the entrainment and off-take are obtained using a test vessel with a height of 2.0m and an inner diameter of 0.3m, and a top break with a diameter of 0.05m. Two-phase mixture levels are measured by an ultrasonic sensor within ±1.77% with respect to the visual level data. Droplet entrainment data are obtained with and without the top break and are compared with the existing pool entrainment data. The present droplet entrainment data have higher values than those of the existing pool entrainment due to (a) the pulling toward the break of the liquid deentrained on the top wall of the vessel and (b) gas acceleration in the vicinity of the break. In the present experiment, droplet entrainment, Efg, strongly depends upon jg/h and is proportional to the 7th power of jg/h in the same way as the off-take data. The empirical correlation for the onset of off-take is developed in terms of the Froude number (Frg) at the break and the non-dimensional inception height (hb/d). This correlation shows agreement with the present experimental data within ±15%. The present off-take quality data show agreement with Schrock's off-take quality correlation with the r.m.s. error of 15.8%

  8. Interpretations of Frequency Domain Analyses of Neural Entrainment: Periodicity, Fundamental Frequency, and Harmonics.

    Science.gov (United States)

    Zhou, Hong; Melloni, Lucia; Poeppel, David; Ding, Nai

    2016-01-01

    Brain activity can follow the rhythms of dynamic sensory stimuli, such as speech and music, a phenomenon called neural entrainment. It has been hypothesized that low-frequency neural entrainment in the neural delta and theta bands provides a potential mechanism to represent and integrate temporal information. Low-frequency neural entrainment is often studied using periodically changing stimuli and is analyzed in the frequency domain using the Fourier analysis. The Fourier analysis decomposes a periodic signal into harmonically related sinusoids. However, it is not intuitive how these harmonically related components are related to the response waveform. Here, we explain the interpretation of response harmonics, with a special focus on very low-frequency neural entrainment near 1 Hz. It is illustrated why neural responses repeating at f Hz do not necessarily generate any neural response at f Hz in the Fourier spectrum. A strong neural response at f Hz indicates that the time scales of the neural response waveform within each cycle match the time scales of the stimulus rhythm. Therefore, neural entrainment at very low frequency implies not only that the neural response repeats at f Hz but also that each period of the neural response is a slow wave matching the time scale of a f Hz sinusoid.

  9. Historical review of entrainment impact estimates and the factors influencing them

    International Nuclear Information System (INIS)

    Englert, T.L.; Boreman, J.

    1988-01-01

    Estimates of entrainment mortality have played a key role in the Hudson River power plant case since the late 1960s. The estimates of entrainment mortality of striped bass due to the operation of Indian Point nuclear plant were first presented by utility and government consultants in 1972. These estimates were derived with the first of many generations of mathematical models. Assumed values had to be used for some of the critical parameters because of the limited amount of data available. The government estimates were much higher as a result of the intentional use of conservative assumptions. As more data became available and model formulations evolved, fewer assumptions were needed, the government estimates declined, and the gap between estimates from the two groups of consultants narrowed markedly. Several factors contributed to the convergence of model estimates, but a key factor was field data showing that more than half of the entrained striped bass survive passage through the plant. The convergence of estimates of entrainment mortality was a key ingredient in the eventual formulation of the settlement agreement and showed that progress had been made in resolving an important portion of the heavily contested issues. 18 refs., 2 figs., 1 tab

  10. Historical development of entrainment models for Hudson River striped bass

    International Nuclear Information System (INIS)

    Christensen, S.W.; Englert, T.L.

    1988-01-01

    In the mid-1960s, concerns surfaced regarding entrainment and impingement of young-of-the-year (age-0) striped bass by electric power generating facilities on the Hudson River. These concerns stimulated the development of increasingly complex models to evaluate the impacts of these facilities. The earliest simplistic formulas, based on empirical data, proved inadequate because of conceptual shortcomings, incomplete development, and lack of data. By 1972, complex transport models based on biological and hydrodynamic principles had been developed and applied by scientists representing both the utilities and the government. Disagreements about the acceptability of these models spurred the development of even more complex models. The entrainment models stimulated the collection of substantial amounts of field data to define the spatial distributions and entrainment survival of early life stages. As the difficulties of accounting for the movement of early life stages from hydrodynamic principles became more evident and as more field data became available, simpler empirical modeling approaches became both practical and defensible. Both empirical and hydrodynamic modeling approaches were applied during the US Environmental Protection Agency's hearings on the Hudson River power case (1977-1980). The main lessons learned from the experience with entrainment-impingement modeling are that complex mechanistic models are not necessarily better than simpler empirical models for young fish, and that care must be taken to construct even the simple models correctly. 29 refs., 4 figs., 1 tab

  11. Modeling of compartment fire

    International Nuclear Information System (INIS)

    Sathiah, P.; Siccama, A.; Visser, D.; Komen, E.

    2011-01-01

    Fire accident in a containment is a serious threat to nuclear reactors. Fire can cause substantial loss to life and property. The risk posed by fire can also exceed the risk from internal events within a nuclear reactor. Numerous research efforts have been performed to understand and analyze the phenomenon of fire in nuclear reactor and its consequences. Modeling of fire is an important subject in the field of fire safety engineering. Two approaches which are commonly used in fire modeling are zonal modeling and field modeling. The objective of this work is to compare zonal and field modeling approach against a pool fired experiment performed in a well-confined compartment. Numerical simulations were performed against experiments, which were conducted within PRISME program under the framework of OECD. In these experiments, effects of ventilation flow rate on heat release rate in a confined and mechanically ventilated compartment is investigated. Time dependent changes in gas temperature and oxygen mass fraction were measured. The trends obtained by numerical simulation performed using zonal model and field model compares well with experiments. Further validation is needed before this code can be used for fire safety analyses. (author)

  12. Fire effects on soil and hydrology

    NARCIS (Netherlands)

    Stoof, C.R.

    2011-01-01

    Fire can significantly increase a landscape’s vulnerability to flooding and erosion events. By removing vegetation, changing soil properties and inducing soil water repellency, fire can increase the risk and erosivity of overland flow. Mitigation of land degradation and flooding events after

  13. New insights into the wind-dust relationship in sandblasting and direct aerodynamic entrainment from wind tunnel experiments

    KAUST Repository

    Parajuli, Sagar Prasad; Zobeck, Ted M.; Kocurek, Gary; Yang, Zong-Liang; Stenchikov, Georgiy L.

    2016-01-01

    Numerous parameterizations have been developed for predicting wind erosion, yet the physical mechanism of dust emission is not fully understood. Sandblasting is thought to be the primary mechanism, but recent studies suggest that dust emission by direct aerodynamic entrainment can be significant under certain conditions. In this work, using wind tunnel experiments, we investigated some of the lesser understood aspects of dust emission in sandblasting and aerodynamic entrainment for three soil types, namely clay, silty clay loam, and clay loam. First, we explored the role of erodible surface roughness on dust emitted by aerodynamic entrainment. Second, we compared the emitted dust concentration in sandblasting and aerodynamic entrainment under a range of wind friction velocities. Finally, we explored the sensitivity of emitted dust particle size distribution (PSD) to soil type and wind friction velocity in these two processes. The dust concentration in aerodynamic entrainment showed strong positive correlation, no significant correlation, and weak negative correlation, for the clay, silty clay loam, and clay loam, respectively, with the erodible soil surface roughness. The dust in aerodynamic entrainment was significant constituting up to 28.3, 41.4, and 146.4% compared to sandblasting for the clay, silty clay loam, and clay loam, respectively. PSD of emitted dust was sensitive to soil type in both sandblasting and aerodynamic entrainment. PSD was sensitive to the friction velocity in aerodynamic entrainment but not in sandblasting. Our results highlight the need to consider the details of sandblasting and direct aerodynamic entrainment processes in parameterizing dust emission in global/regional climate models.

  14. New insights into the wind-dust relationship in sandblasting and direct aerodynamic entrainment from wind tunnel experiments

    KAUST Repository

    Parajuli, Sagar Prasad

    2016-01-22

    Numerous parameterizations have been developed for predicting wind erosion, yet the physical mechanism of dust emission is not fully understood. Sandblasting is thought to be the primary mechanism, but recent studies suggest that dust emission by direct aerodynamic entrainment can be significant under certain conditions. In this work, using wind tunnel experiments, we investigated some of the lesser understood aspects of dust emission in sandblasting and aerodynamic entrainment for three soil types, namely clay, silty clay loam, and clay loam. First, we explored the role of erodible surface roughness on dust emitted by aerodynamic entrainment. Second, we compared the emitted dust concentration in sandblasting and aerodynamic entrainment under a range of wind friction velocities. Finally, we explored the sensitivity of emitted dust particle size distribution (PSD) to soil type and wind friction velocity in these two processes. The dust concentration in aerodynamic entrainment showed strong positive correlation, no significant correlation, and weak negative correlation, for the clay, silty clay loam, and clay loam, respectively, with the erodible soil surface roughness. The dust in aerodynamic entrainment was significant constituting up to 28.3, 41.4, and 146.4% compared to sandblasting for the clay, silty clay loam, and clay loam, respectively. PSD of emitted dust was sensitive to soil type in both sandblasting and aerodynamic entrainment. PSD was sensitive to the friction velocity in aerodynamic entrainment but not in sandblasting. Our results highlight the need to consider the details of sandblasting and direct aerodynamic entrainment processes in parameterizing dust emission in global/regional climate models.

  15. Using Logistic Regression To Predict the Probability of Debris Flows Occurring in Areas Recently Burned By Wildland Fires

    Science.gov (United States)

    Rupert, Michael G.; Cannon, Susan H.; Gartner, Joseph E.

    2003-01-01

    Logistic regression was used to predict the probability of debris flows occurring in areas recently burned by wildland fires. Multiple logistic regression is conceptually similar to multiple linear regression because statistical relations between one dependent variable and several independent variables are evaluated. In logistic regression, however, the dependent variable is transformed to a binary variable (debris flow did or did not occur), and the actual probability of the debris flow occurring is statistically modeled. Data from 399 basins located within 15 wildland fires that burned during 2000-2002 in Colorado, Idaho, Montana, and New Mexico were evaluated. More than 35 independent variables describing the burn severity, geology, land surface gradient, rainfall, and soil properties were evaluated. The models were developed as follows: (1) Basins that did and did not produce debris flows were delineated from National Elevation Data using a Geographic Information System (GIS). (2) Data describing the burn severity, geology, land surface gradient, rainfall, and soil properties were determined for each basin. These data were then downloaded to a statistics software package for analysis using logistic regression. (3) Relations between the occurrence/non-occurrence of debris flows and burn severity, geology, land surface gradient, rainfall, and soil properties were evaluated and several preliminary multivariate logistic regression models were constructed. All possible combinations of independent variables were evaluated to determine which combination produced the most effective model. The multivariate model that best predicted the occurrence of debris flows was selected. (4) The multivariate logistic regression model was entered into a GIS, and a map showing the probability of debris flows was constructed. The most effective model incorporates the percentage of each basin with slope greater than 30 percent, percentage of land burned at medium and high burn severity

  16. Heterogeneous nucleation of entrained eutectic Si in high purity melt spun Al-Si alloys investigated by entrained droplet technique and DSC

    International Nuclear Information System (INIS)

    Li, J H; Schumacher, P; Albu, M; Hofer, F; Ludwig, T H; Arnberg, L

    2016-01-01

    Entrained droplet technique and DSC analyses were employed to investigate the influence of trace elements of Sr, Eu and P on the heterogeneous nucleation of entrained eutectic Si in high purity melt spun Al-5wt.% Si alloys. Sr and Eu addition was found to exert negative effects on the nucleation process, while an increased undercooling was observed. This can be attributed to the formation of phosphide compounds having a lower free energy and hence may preferentially form compared to AlP. Only a trace P addition was found to have a profound effect on the nucleation process. The nucleation kinetics is discussed on the basis of the classical nucleation theory and the free growth model, respectively. The estimated AlP patch size was found to be sufficient for the free growth of Si to occur within the droplets, which strongly indicates that the nucleation of Si on an AlP patch or AlP particle is a limiting step for free growth. The maximum nucleation site density within one droplet is directly related to the size distribution of AlP particles or AlP patches for Si nucleation, but is independent of the cooling rates. Although the nucleation conditions were optimized in entrained droplet experiments, the observed mechanisms are also valid at moderate cooling conditions, such as in shape casting. (paper)

  17. Reflooding phase of the LOCA - state of the art II. Rewetting and liquid entrainment

    International Nuclear Information System (INIS)

    Elias, E.; Yadigaroglu, G.

    1977-01-01

    Understanding the mechanisms by which hot fuel rods quench and the physics of liquid droplet entrainment is important for the analysis of the reflooding phase of the LOCA. Published models of the rewetting process include simple one-dimensional solutions. The basic physical assumptions of these models and the numerical values assigned to the various parameters, as well as empirical rewetting correlations are discussed. The various mechanisms for liquid droplet entrainment and analytical formulations of the critical gas velocity and of the droplet diameter at the onset of entrainment are reviewed

  18. Quantification of the effect of oil layer thickness on entrainment of surface oil

    NARCIS (Netherlands)

    Klaas Dijkstra; Albertinka J. Murk; Marieke Zeinstra-Helfrich; Wierd Koops

    2015-01-01

    This study quantifies the effect of oil layer thickness on entrainment and dispersion of oil into seawater, using a plunging jet with a camera system. In contrast to what is generally assumed, we revealed that for the low viscosity “surrogate MC252 oil” we used, entrainment rate is directly

  19. The effect of surfactant on stratified and stratifying gas-liquid flows

    Science.gov (United States)

    Heiles, Baptiste; Zadrazil, Ivan; Matar, Omar

    2013-11-01

    We consider the dynamics of a stratified/stratifying gas-liquid flow in horizontal tubes. This flow regime is characterised by the thin liquid films that drain under gravity along the pipe interior, forming a pool at the bottom of the tube, and the formation of large-amplitude waves at the gas-liquid interface. This regime is also accompanied by the detachment of droplets from the interface and their entrainment into the gas phase. We carry out an experimental study involving axial- and radial-view photography of the flow, in the presence and absence of surfactant. We show that the effect of surfactant is to reduce significantly the average diameter of the entrained droplets, through a tip-streaming mechanism. We also highlight the influence of surfactant on the characteristics of the interfacial waves, and the pressure gradient that drives the flow. EPSRC Programme Grant EP/K003976/1.

  20. Slowly rotating general relativistic superfluid neutron stars with relativistic entrainment

    International Nuclear Information System (INIS)

    Comer, G.L.

    2004-01-01

    Neutron stars that are cold enough should have two or more superfluids or supercondutors in their inner crusts and cores. The implication of superfluidity or superconductivity for equilibrium and dynamical neutron star states is that each individual particle species that forms a condensate must have its own, independent number density current and equation of motion that determines that current. An important consequence of the quasiparticle nature of each condensate is the so-called entrainment effect; i.e., the momentum of a condensate is a linear combination of its own current and those of the other condensates. We present here the first fully relativistic modeling of slowly rotating superfluid neutron stars with entrainment that is accurate to the second-order in the rotation rates. The stars consist of superfluid neutrons, superconducting protons, and a highly degenerate, relativistic gas of electrons. We use a relativistic σ-ω mean field model for the equation of state of the matter and the entrainment. We determine the effect of a relative rotation between the neutrons and protons on a star's total mass, shape, and Kepler, mass-shedding limit

  1. Fire resistant nuclear fuel cask

    International Nuclear Information System (INIS)

    Heckman, R.C.; Moss, M.

    1979-01-01

    The disclosure is directed to a fire resistant nuclear fuel cask employing reversibly thermally expansible bands between adjacent cooling fins such that normal outward flow of heat is not interfered with, but abnormal inward flow of heat is impeded or blocked

  2. Smoke flow temperature beneath tunnel ceiling for train fire at subway station: Reduced-scale experiments and correlations

    International Nuclear Information System (INIS)

    Meng, Na; Wang, Qiang; Liu, Zhaoxia; Li, Xiao; Yang, He

    2017-01-01

    Highlights: • Reduced-scale experiments on train fire at subway station. • Smoke flow temperature beneath tunnel ceiling measured and correlated. • Effect of platform-tunnel conjunction door type on smoke temperature is clarified. - Abstract: This paper is to investigate the smoke flow temperature beneath tunnel ceiling for a train on fire stopping besides a subway station. Experiments were carried out in a reduced-scale (1:10) subway station model to study the maximum smoke temperature and the longitudinal temperature distribution beneath the tunnel ceiling by considering platform-tunnel conjunction doors of two types: the full-seal platform screen door (PSD) and the full-height safety door. For the maximum temperature beneath the tunnel ceiling, it is found to be well correlated non-dimensionally with heat release rate by a 3.65 and a 2.92 power law function for the full-seal platform screen door and the full-height safety door, respectively. For the longitudinal temperature distribution along the tunnel ceiling, it can be well correlated by an exponential function for both types of platform-tunnel conjunction doors. Concerning the effect of the door type, the maximum temperature is lower and the longitudinal temperature decays faster for full-height safety door than that for full-seal PSD. This is due to that with the full-height safety door, the effective width of the tunnel ceiling is widened, which results in more heat losses from the smoke flow to the ceiling.

  3. Large Eddy Simulation of Heat Entrainment Under Arctic Sea Ice

    Science.gov (United States)

    Ramudu, Eshwan; Gelderloos, Renske; Yang, Di; Meneveau, Charles; Gnanadesikan, Anand

    2018-01-01

    Arctic sea ice has declined rapidly in recent decades. The faster than projected retreat suggests that free-running large-scale climate models may not be accurately representing some key processes. The small-scale turbulent entrainment of heat from the mixed layer could be one such process. To better understand this mechanism, we model the Arctic Ocean's Canada Basin, which is characterized by a perennial anomalously warm Pacific Summer Water (PSW) layer residing at the base of the mixed layer and a summertime Near-Surface Temperature Maximum (NSTM) within the mixed layer trapping heat from solar radiation. We use large eddy simulation (LES) to investigate heat entrainment for different ice-drift velocities and different initial temperature profiles. The value of LES is that the resolved turbulent fluxes are greater than the subgrid-scale fluxes for most of our parameter space. The results show that the presence of the NSTM enhances heat entrainment from the mixed layer. Additionally there is no PSW heat entrained under the parameter space considered. We propose a scaling law for the ocean-to-ice heat flux which depends on the initial temperature anomaly in the NSTM layer and the ice-drift velocity. A case study of "The Great Arctic Cyclone of 2012" gives a turbulent heat flux from the mixed layer that is approximately 70% of the total ocean-to-ice heat flux estimated from the PIOMAS model often used for short-term predictions. Present results highlight the need for large-scale climate models to account for the NSTM layer.

  4. Soot, organics and ultrafine ash from air- and oxy-fired coal combustion

    Science.gov (United States)

    This paper is concerned with determining the effects of oxy-combustion of coal on the composition of the ultrafine fly ash. To this end, a 10 W externally heated entrained flow furnace was modified to allow the combustion of pulverized coal in flames under practically relevant s...

  5. Accuracy of circadian entrainment under fluctuating light conditions : Contributions of phase and period responses

    NARCIS (Netherlands)

    Beersma, DGM; Daan, S; Hut, RA

    The accuracy with which a circadian pacemaker can entrain to an environmental 24-h zeitgeber signal depends on (a) characteristics of the entraining signal and (b) response characteristics and intrinsic stability of the pacemaker itself. Position of the sun, weather conditions, shades, and

  6. Post-fire debris flow prediction in Western United States: Advancements based on a nonparametric statistical technique

    Science.gov (United States)

    Nikolopoulos, E. I.; Destro, E.; Bhuiyan, M. A. E.; Borga, M., Sr.; Anagnostou, E. N.

    2017-12-01

    Fire disasters affect modern societies at global scale inducing significant economic losses and human casualties. In addition to their direct impacts they have various adverse effects on hydrologic and geomorphologic processes of a region due to the tremendous alteration of the landscape characteristics (vegetation, soil properties etc). As a consequence, wildfires often initiate a cascade of hazards such as flash floods and debris flows that usually follow the occurrence of a wildfire thus magnifying the overall impact in a region. Post-fire debris flows (PFDF) is one such type of hazards frequently occurring in Western United States where wildfires are a common natural disaster. Prediction of PDFD is therefore of high importance in this region and over the last years a number of efforts from United States Geological Survey (USGS) and National Weather Service (NWS) have been focused on the development of early warning systems that will help mitigate PFDF risk. This work proposes a prediction framework that is based on a nonparametric statistical technique (random forests) that allows predicting the occurrence of PFDF at regional scale with a higher degree of accuracy than the commonly used approaches that are based on power-law thresholds and logistic regression procedures. The work presented is based on a recently released database from USGS that reports a total of 1500 storms that triggered and did not trigger PFDF in a number of fire affected catchments in Western United States. The database includes information on storm characteristics (duration, accumulation, max intensity etc) and other auxiliary information of land surface properties (soil erodibility index, local slope etc). Results show that the proposed model is able to achieve a satisfactory prediction accuracy (threat score > 0.6) superior of previously published prediction frameworks highlighting the potential of nonparametric statistical techniques for development of PFDF prediction systems.

  7. Entrainment and phase-shifting by centrifugation abolished in mice lacking functional vestibular input

    Science.gov (United States)

    Fuller, Charles; Ringgold, Kristyn

    The circadian pacemaker can be phase shifted and entrained by appropriately timed locomotor activity, however the mechanism(s) involved remain poorly understood. Recent work in our lab has suggested the involvement of the vestibular otolith organs in activity-induced changes within the circadian timing system (CTS). For example, we have shown that changes in circa-dian period and phase in response to locomotion (wheel running) require functional macular gravity receptors. We believe the neurovestibular system is responsible for the transduction of gravitoinertial input associated with the types of locomotor activity that are known to af-fect the pacemaker. This study investigated the hypothesis that daily, timed gravitoinertial stimuli, as applied by centrifugation. would induce entrainment of circadian rhythms in only those animals with functional afferent vestibular input. To test this hypothesis, , chemically labyrinthectomized (Labx) mice, mice lacking macular vestibular input (head tilt or hets) and wildtype (WT) littermates were implanted i.p. with biotelemetry and individually housed in a 4-meter diameter centrifuge in constant darkness (DD). After 2 weeks in DD, the mice were exposed daily to 2G via centrifugation from 1000-1200 for 9 weeks. Only WT mice showed entrainment to the daily 2G pulse. The 2G pulse was then re-set to occur at 1200-1400 for 4 weeks. Only WT mice demonstrated a phase shift in response to the re-setting of the 2G pulse and subsequent re-entrainment to the new centrifugation schedule. These results provide further evidence that gravitoinertial stimuli require a functional vestibular system to both en-train and phase shift the CTS. Entrainment among only WT mice supports the role of macular gravity receptive cells in modulation of the CTS while also providing a functional mechanism by which gravitoinertial stimuli, including locomotor activity, may affect the pacemaker.

  8. Independence of circadian entrainment state and responses to melatonin in male Siberian hamsters

    Directory of Open Access Journals (Sweden)

    Gorman Michael R

    2003-10-01

    Full Text Available Abstract Background Seasonal fluctuations in physiology and behavior depend on the duration of nocturnal melatonin secretion programmed by the circadian system. A melatonin signal of a given duration, however, can elicit different responses depending on whether an animal was previously exposed to longer or shorter photoperiod signals (i.e., its photoperiodic history. This report examined in male Siberian hamsters which of two aspects of photoperiod history – prior melatonin exposure or entrainment state of the circadian system – is critical for generating contingent responses to a common photoperiodic signal. Results In Experiment #1, daily melatonin infusions of 5 or 10 h duration stimulated or inhibited gonadal growth, respectively, but had no effect on entrainment of the locomotor activity rhythm to long or short daylengths, thereby demonstrating that melatonin history and entrainment status could be experimentally dissociated. These manipulations were repeated in Experiment #2, and animals were subsequently exposed to a 12 week regimen of naturalistic melatonin signals shown in previous experiments to reveal photoperiodic history effects. Gonadal responses differed as a function of prior melatonin exposure but were unaffected by the circadian entrainment state. Experiment #3 demonstrated that a new photoperiodic history could be imparted during four weeks of exposure to long photoperiods. This effect, moreover, was blocked in animals treated concurrently with constant release melatonin capsules that obscured the endogenous melatonin signal: Following removal of the implants, the gonadal response depended not on the immediately antecedent circadian entrainment state, but on the more remote photoperiodic conditions prior to the melatonin implant. Conclusions The interpretation of photoperiodic signals as a function of prior conditions depends specifically on the history of melatonin exposure. The photoperiodic regulation of circadian

  9. Wind profiler mixing depth and entrainment measurements with chemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Angevine, W.M.; Trainer, M.; Parrish, D.D.; Buhr, M.P.; Fehsenfeld, F.C. [NOAA Aeronomy Lab., Boulder, CO (United States); Kok, G.L. [NCAR Research Aviation Facility, Boulder, CO (United States)

    1994-12-31

    Wind profiling radars operating at 915 MHz have been present at a number of regional air quality studies. The profilers can provide a continuous, accurate record of the depth of the convective mixed layer with good time resolution. Profilers also provide information about entrainment at the boundary layer top. Mixing depth data from several days of the Rural Oxidants in the Southern Environment II (ROSE II) study in Alabama in June, 1992 are presented. For several cases, chemical measurements from aircraft and ground-based instruments are shown to correspond to mixing depth and entrainment zone behavior observed by the profiler.

  10. Literature search on slip and entrainment in a reactor cooling channel

    International Nuclear Information System (INIS)

    Beck, W.; Schuetzle, R.

    1976-11-01

    Models and correlations are presented describing slip and entrainment during the refilling phase after a LOCA in a PWR. Their applicability is investigated for a computer program to comprehend the processes in a reactor cooling channel during the refilling phase of the core. The models of Levy provide no realistic data for the problem discussed. Bankoff and Jones seem to predict reasonable results. Their half empirical relation is valid for void fractions α up to α approximately 0.75. Empirical correlations are applicable in smaller α-regions. Some relations cannot be evaluated on account of unknown quantities. When entrainment is concerned, often only the critical gas velocity at the onset is stated. It varies strongly. The correlations, describing the entrainment E, defined by the gas-stream, along the vertical axis z, provide values for E between 0.6 and 0.7 after a characteristic ascent at z = 0.5 - 0.6. Restrictions are frequently unknown. (orig./HP) [de

  11. Effects of entrainment through Oconee Nuclear Station on carbon-14 assimilation rates of phytoplankton

    International Nuclear Information System (INIS)

    Kreh, T.V.; Derwort, J.E.

    1976-01-01

    Carbon assimilation rates of phytoplankton communities entrained through Oconee Nuclear Station were measured on six dates during 1974. Thermal, mechanical, condenser, and multiple entrainment effects on uptake rates were compared by incubating samples in vitro in controlled-temperature water baths. Duplicate light and dark bottles containing water from four cooling-system locations were exposed to temperatures approximating intake and discharge temperatures. The relationships were variable, but exposure of the hypolimnetic intake water at near-discharge temperatures (thermal effect) stimulated primary productivity in four of six experiments. Multiple entrainment and mechanical effects caused no consistent change in assimilation rates

  12. Assessment of the Effects of Entrainment and Wind Shear on Nuclear Cloud Rise Modeling

    Science.gov (United States)

    Zalewski, Daniel; Jodoin, Vincent

    2001-04-01

    Accurate modeling of nuclear cloud rise is critical in hazard prediction following a nuclear detonation. This thesis recommends improvements to the model currently used by DOD. It considers a single-term versus a three-term entrainment equation, the value of the entrainment and eddy viscous drag parameters, as well as the effect of wind shear in the cloud rise following a nuclear detonation. It examines departures from the 1979 version of the Department of Defense Land Fallout Interpretive Code (DELFIC) with the current code used in the Hazard Prediction and Assessment Capability (HPAC) code version 3.2. The recommendation for a single-term entrainment equation, with constant value parameters, without wind shear corrections, and without cloud oscillations is based on both a statistical analysis using 67 U.S. nuclear atmospheric test shots and the physical representation of the modeling. The statistical analysis optimized the parameter values of interest for four cases: the three-term entrainment equation with wind shear and without wind shear as well as the single-term entrainment equation with and without wind shear. The thesis then examines the effect of cloud oscillations as a significant departure in the code. Modifications to user input atmospheric tables are identified as a potential problem in the calculation of stabilized cloud dimensions in HPAC.

  13. Close entrainment of massive molecular gas flows by radio bubbles in the central galaxy of Abell 1795

    Science.gov (United States)

    Russell, H. R.; McNamara, B. R.; Fabian, A. C.; Nulsen, P. E. J.; Combes, F.; Edge, A. C.; Hogan, M. T.; McDonald, M.; Salomé, P.; Tremblay, G.; Vantyghem, A. N.

    2017-12-01

    We present new ALMA observations tracing the morphology and velocity structure of the molecular gas in the central galaxy of the cluster Abell 1795. The molecular gas lies in two filaments that extend 5-7 kpc to the N and S from the nucleus and project exclusively around the outer edges of two inner radio bubbles. Radio jets launched by the central active galactic nucleus have inflated bubbles filled with relativistic plasma into the hot atmosphere surrounding the central galaxy. The N filament has a smoothly increasing velocity gradient along its length from the central galaxy's systemic velocity at the nucleus to -370 km s^{-1}, the average velocity of the surrounding galaxies, at the furthest extent. The S filament has a similarly smooth but shallower velocity gradient and appears to have partially collapsed in a burst of star formation. The close spatial association with the radio lobes, together with the ordered velocity gradients and narrow velocity dispersions, shows that the molecular filaments are gas flows entrained by the expanding radio bubbles. Assuming a Galactic XCO factor, the total molecular gas mass is 3.2 ± 0.2 × 109 M⊙. More than half lies above the N radio bubble. Lifting the molecular clouds appears to require an infeasibly efficient coupling between the molecular gas and the radio bubble. The energy required also exceeds the mechanical power of the N radio bubble by a factor of 2. Stimulated feedback, where the radio bubbles lift low-entropy X-ray gas that becomes thermally unstable and rapidly cools in situ, provides a plausible model. Multiple generations of radio bubbles are required to lift this substantial gas mass. The close morphological association then indicates that the cold gas either moulds the newly expanding bubbles or is itself pushed aside and shaped as they inflate.

  14. Late Holocene geomorphic record of fire in ponderosa pine and mixed-conifer forests, Kendrick Mountain, northern Arizona, USA

    Science.gov (United States)

    Jenkins, S.E.; Hull, Sieg C.; Anderson, D.E.; Kaufman, D.S.; Pearthree, P.A.

    2011-01-01

    Long-term fire history reconstructions enhance our understanding of fire behaviour and associated geomorphic hazards in forested ecosystems. We used 14C ages on charcoal from fire-induced debris-flow deposits to date prehistoric fires on Kendrick Mountain, northern Arizona, USA. Fire-related debris-flow sedimentation dominates Holocene fan deposition in the study area. Radiocarbon ages indicate that stand-replacing fire has been an important phenomenon in late Holocene ponderosa pine (Pinus ponderosa) and ponderosa pine-mixed conifer forests on steep slopes. Fires have occurred on centennial scales during this period, although temporal hiatuses between recorded fires vary widely and appear to have decreased during the past 2000 years. Steep slopes and complex terrain may be responsible for localised crown fire behaviour through preheating by vertical fuel arrangement and accumulation of excessive fuels. Holocene wildfire-induced debris flow events occurred without a clear relationship to regional climatic shifts (decadal to millennial), suggesting that interannual moisture variability may determine fire year. Fire-debris flow sequences are recorded when (1) sufficient time has passed (centuries) to accumulate fuels; and (2) stored sediment is available to support debris flows. The frequency of reconstructed debris flows should be considered a minimum for severe events in the study area, as fuel production may outpace sediment storage. ?? IAWF 2011.

  15. Fire Emulator/Detector Evaluator

    Data.gov (United States)

    Federal Laboratory Consortium — Description:The fire emulator/detector evaluator (FE/DE) is a computer-controlled flow tunnel used to re-create the environments surrounding detectors in the early...

  16. Standard for prevention of gas entrainment phenomena in fast reactors. (1) Validations of CFD methods for reproducibilities of gas entrainment phenomena; 高速炉におけるガス巻込み現象の防止基準. (1) 数値解析によるガス巻込み現象再現精度の検証

    Energy Technology Data Exchange (ETDEWEB)

    Ohshima, Hiroyuki; Uchibori, Akihiro; Ito, Kei; Sakai, Takaaki [Japan Atomic Energy Agency, Advanced Nuclear System Research and Development Directorate, Oarai, Ibaraki (Japan); Tanaka, Nobuatsu [Ibaraki University, Department of Mechanical Engineering, Hitachi, Ibaraki (Japan); Eguchi, Yuzuru [Central Research Institute of Electric Power Industry (CRIEPI), Civil Engineering Research Laboratory, Abiko, Chiba (Japan); Nishimura, Motohiko [Kawasaki Heavy Industries, Ltd., Technical Institute, Akashi, Hyogo (Japan); Kunugi, Tomoaki [Kyoto Univ., Department of Nuclear Engineering, Kyoto, Kyoto (Japan)

    2012-12-15

    It is of importance for stable operations of sodium-cooled fast reactors (SFRs) to prevent gas entrainment (GE) phenomena due to free surface vortices. The entrained gas flow rate should be below an allowance level. However, theoretical determination of universal onset conditions of GE is difficult due to nonlinear characteristics of GE phenomena. Therefore, the authors have been developing an evaluation method for GE based on computational fluid dynamics (CFD) methods. In this study, we determine a suitable CFD method for GE phenomena from several candidates through some numerical benchmarks. As a result, we obtain the following guideline for the vortex-induced gas entrainment. The free vortex flow around the vortex core can be correctly evaluated by using appropriate numerical models, such as sufficient mesh resolution, suitable advection solver, suitable turbulence and free surface modeling. From the geometrical viewpoint, the jagged description of the curved boundary using a rectangular mesh is not suitable since it damps rotating flow. As for turbulence modeling, which is especially investigated in this paper, direct numerical simulation (DNS) without any turbulent model is strongly recommended, but RNG k-ε and LES are acceptable. Lastly, we apply the recommended methods to the numerical analysis of a large-scale (>1/2) test experiment. The numerical results show good agreement with the onset condition of the GE observed in the experiments. This fact indicates that our recommended CFD methods are applicable to the GE phenomena in SFRs. In the next paper, a GE evaluation method is developed, which can calculate GE occurrences based on the results of numerical simulations performed in accordance with the simulation guideline proposed in this paper. (author)

  17. Crustal entrainment and pulsar glitches.

    Science.gov (United States)

    Chamel, N

    2013-01-04

    Large pulsar frequency glitches are generally interpreted as sudden transfers of angular momentum between the neutron superfluid permeating the inner crust and the rest of the star. Despite the absence of viscous drag, the neutron superfluid is strongly coupled to the crust due to nondissipative entrainment effects. These effects are shown to severely limit the maximum amount of angular momentum that can possibly be transferred during glitches. In particular, it is found that the glitches observed in the Vela pulsar require an additional reservoir of angular momentum.

  18. Fire simulation of the canister transfer and installation vehicle

    International Nuclear Information System (INIS)

    Peltokorpi, L.

    2012-12-01

    A pyrolysis model of the canister transfer and installation vehicle was developed and vehicle fires in the final disposal tunnel and in the central tunnel were simulated using the fire simulation program FDS (Fire Dynamics Simulator). For comparison, same vehicle fire was also simulated at conditions in which the fire remained as a fuel controlled during the whole simulation. The purpose of the fire simulations was to simulate the fire behaviour realistically taking into account for example the limitations coming from the lack of oxygen. The material parameters for the rubber were defined and the simulation models for the tyres developed by simulating the fire test of a front wheel loader rubber tyre done by SP Technical Research Institute of Sweden. In these simulations the most important phenomena were successfully brought out but the timing of the phenomena was difficult. The final values for the rubber material parameters were chosen so that the simulated fire behaviour was at least as intense as the measured one. In the vehicle fire simulations a hydraulic oil or diesel leak causing a pool fire size of 2 MW and 2 m 2 was assumed. The pool fire was assumed to be located under the tyres of the SPMT (Self Propelled Modular Transporters) transporter. In each of the vehicle fire simulations only the tyres of the SPMT transporter were observed to be burning whereas the tyres of the trailer remained untouched. In the fuel controlled fire the maximum power was slightly under 10 MW which was reached in about 18 minutes. In the final disposal tunnel the growth of the fire was limited due to the lack of oxygen and the relatively fast air flows existing in the tunnel. Fast air flows caused the flame spreading to be limited to the certain directions. In the final disposal tunnel fire the maximum power was slightly over 7 MW which was reached about 8 minutes after the ignition. In the central tunnel there was no shortage of oxygen but the spread of the fire was limited due

  19. Experimental study on fundamental performance of reverse flow diverters

    International Nuclear Information System (INIS)

    Fan Yanfang; Xu Cong; Jing Shan

    2008-01-01

    The Reverse Flow Diverter (RFD) is one of the key components affecting the liquid-delivered efficiency. The effects of inflow structure, outflow structure, area ratio and suction gap on the performance of RFDs were studied in this paper. It can be found experimentally that expected entrainment phenomenon can be achieved when the outlet velocity of fluid for RFDs' inflow structure is sufficient. There is less liquid delivered by an RFD with a long receiver than that without a receiver. Because of back-flow caused by vortex separation, oversize area ratio cannot have better entrainment phenomenon and the optimum area ratio is 1.5. When the ratio of suction gap length to inlet diameter of outflow structure is 0.9-1.0, the excellent liquid-delivered efficiency can be obtained. (authors)

  20. Fish-protection devices at unscreened water diversions can reduce entrainment: evidence from behavioural laboratory investigations

    Science.gov (United States)

    Poletto, Jamilynn B.; Cocherell, Dennis E.; Mussen, Timothy D.; Ercan, Ali; Bandeh, Hossein; Kavvas, M. Levent; Cech, Joseph J.; Fangue, Nann A.

    2015-01-01

    Diversion (i.e. extraction) of water from rivers and estuaries can potentially affect native wildlife populations if operation is not carefully managed. For example, open, unmodified water diversions can act as a source of injury or mortality to resident or migratory fishes from entrainment and impingement, and can cause habitat degradation and fragmentation. Fish-protection devices, such as exclusion screens, louvres or sensory deterrents, can physically or behaviourally deter fish from approaching or being entrained into water diversions. However, empirical assessment of their efficacy is often lacking or is investigated only for particular economically or culturally important fishes, such as salmonids. The Southern population of anadromous green sturgeon (Acipenser medirostris) is listed as threatened in California, and there is a high density of water diversions located within their native range (the Sacramento–San Joaquin watershed). Coupled with their unique physiology and behaviour compared with many other fishes native to California, the green sturgeon is susceptible to entrainment into diversions and is an ideal species with which to study the efficacy of mitigation techniques. Therefore, we investigated juvenile green sturgeon (188–202 days post-hatch) in the presence of several fish-protection devices to assess behaviour and entrainment risk. Using a large experimental flume (∼500 kl), we found that compared with an open diversion pipe (control), the addition of a trash-rack box, louvre box, or perforated cylinder on the pipe inlet all significantly reduced the proportion of fish that were entrained through the pipe (P = 0.03, P = 0.028, and P = 0.028, respectively). Likewise, these devices decreased entrainment risk during a single movement past the pipe by between 60 and 96%. These fish-protection devices should decrease the risk of fish entrainment during water-diversion activities. PMID:27293725

  1. Turbulence, dynamic similarity and scale effects in high-velocity free-surface flows above a stepped chute

    Science.gov (United States)

    Felder, Stefan; Chanson, Hubert

    2009-07-01

    In high-velocity free-surface flows, air entrainment is common through the interface, and intense interactions take place between turbulent structures and entrained bubbles. Two-phase flow properties were measured herein in high-velocity open channel flows above a stepped chute. Detailed turbulence measurements were conducted in a large-size facility, and a comparative analysis was applied to test the validity of the Froude and Reynolds similarities. The results showed consistently that the Froude similitude was not satisfied using a 2:1 geometric scaling ratio. Lesser number of entrained bubbles and comparatively greater bubble sizes were observed at the smaller Reynolds numbers, as well as lower turbulence levels and larger turbulent length and time scales. The results implied that small-size models did underestimate the rate of energy dissipation and the aeration efficiency of prototype stepped spillways for similar flow conditions. Similarly a Reynolds similitude was tested. The results showed also some significant scale effects. However a number of self-similar relationships remained invariant under changes of scale and confirmed the analysis of Chanson and Carosi (Exp Fluids 42:385-401, 2007). The finding is significant because self-similarity may provide a picture general enough to be used to characterise the air-water flow field in large prototype channels.

  2. Spontaneous Entrainment of Running Cadence to Music Tempo.

    Science.gov (United States)

    Van Dyck, Edith; Moens, Bart; Buhmann, Jeska; Demey, Michiel; Coorevits, Esther; Dalla Bella, Simone; Leman, Marc

    Since accumulating evidence suggests that step rate is strongly associated with running-related injuries, it is important for runners to exercise at an appropriate running cadence. As music tempo has been shown to be capable of impacting exercise performance of repetitive endurance activities, it might also serve as a means to (re)shape running cadence. The aim of this study was to validate the impact of music tempo on running cadence. Sixteen recreational runners ran four laps of 200 m (i.e. 800 m in total); this task was repeated 11 times with a short break in between each four-lap sequence. During the first lap of a sequence, participants ran at a self-paced tempo without musical accompaniment. Running cadence of the first lap was registered, and during the second lap, music with a tempo matching the assessed cadence was played. In the final two laps, the music tempo was either increased/decreased by 3.00, 2.50, 2.00, 1.50, or 1.00 % or was kept stable. This range was chosen since the aim of this study was to test spontaneous entrainment (an average person can distinguish tempo variations of about 4 %). Each participant performed all conditions. Imperceptible shifts in musical tempi in proportion to the runner's self-paced running tempo significantly influenced running cadence ( p  tempo conditions and adaptation in running cadence ( p  effect of condition on the level of entrainment was revealed ( p  effects of music tempo on running cadence can only be obtained up to a certain level of tempo modification. Finally, significantly higher levels of tempo entrainment were found for female participants compared to their male counterparts ( p  music tempo could serve as an unprompted means to impact running cadence. As increases in step rate may prove beneficial in the prevention and treatment of common running-related injuries, this finding could be especially relevant for treatment purposes, such as exercise prescription and gait retraining. Music tempo

  3. Relativistic mean field model for entrainment in general relativistic superfluid neutron stars

    International Nuclear Information System (INIS)

    Comer, G.L.; Joynt, R.

    2003-01-01

    General relativistic superfluid neutron stars have a significantly more intricate dynamics than their ordinary fluid counterparts. Superfluidity allows different superfluid (and superconducting) species of particles to have independent fluid flows, a consequence of which is that the fluid equations of motion contain as many fluid element velocities as superfluid species. Whenever the particles of one superfluid interact with those of another, the momentum of each superfluid will be a linear combination of both superfluid velocities. This leads to the so-called entrainment effect whereby the motion of one superfluid will induce a momentum in the other superfluid. We have constructed a fully relativistic model for entrainment between superfluid neutrons and superconducting protons using a relativistic σ-ω mean field model for the nucleons and their interactions. In this context there are two notions of 'relativistic': relativistic motion of the individual nucleons with respect to a local region of the star (i.e. a fluid element containing, say, an Avogadro's number of particles), and the motion of fluid elements with respect to the rest of the star. While it is the case that the fluid elements will typically maintain average speeds at a fraction of that of light, the supranuclear densities in the core of a neutron star can make the nucleons themselves have quite high average speeds within each fluid element. The formalism is applied to the problem of slowly rotating superfluid neutron star configurations, a distinguishing characteristic being that the neutrons can rotate at a rate different from that of the protons

  4. A new technology for air-entrainment of concrete

    DEFF Research Database (Denmark)

    Laustsen, Sara; Hasholt, Marianne Tange; Jensen, Ole Mejlhede

    2008-01-01

    This paper describes a new technology for air-entrainment of concrete. The technology is based on the addition of dry superabsorbent polymers (SAP) to the concrete. A large amount of small internal water reservoirs are formed during mixing when SAP absorbs water and swells. The internal water......-entrainment include stability of the air void system and improved control of both the amount of added air and the air void size. The new technology based on SAP has been tested in freeze-thaw experiments, where the amount of surface scaling was measured. The results clearly show that SAP is beneficial for frost...... reservoirs are distributed throughout the concrete. During the hydration process the cement paste imbibes water from the water-filled SAP voids. Thereby the water-filled SAP voids turn into partly air-filled voids. The advantages of the SAP-based technology compared to traditional chemical air...

  5. Dust mobilization by high-speed vapor flow under LOVA

    International Nuclear Information System (INIS)

    Matsuki, K.; Suzuki, S.; Ebara, S.; Yokomine, T.; Shimizu, A.

    2006-01-01

    In the safety analysis on the International Thermonuclear Experimental Reactor (ITER), the ingress of coolant (ICE) event and the loss of vacuum (LOVA) event are considered as one of the most serious accident. On the assumption of LOVA occurring after ICE, it is inferable that activated dusts are under the wet condition. Transport behavior of in-vessel activated dusts under the wet condition is not well understood in comparison with the dry case. In this study, we experimentally investigated the entrainment behavior of dust under LOVA after ICE. We measured dust entrainment by high-speed humid airflow with phase change. Graphite dusts and glass beads are used as substitutions for mobile inventory. The relations among the relative humidity, the entrainment of particles in the exhaust gas flow and the adhesion rate of dust particles on the pipe wall have been made clear, as has the distribution profile of dust deposition on the pipe wall. The entrainment ratio decreased as the relative humidity increased and increased as the initial pressure difference increased

  6. Large eddy simulation of a mechanically ventilated compartment fire for nuclear applications

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Bao P. [Dalian Univ. of Technology (China). Faculty of Energy and Power Engineering; Wen, Jennifer X. [Warwick Univ. (United Kingdom). Warwick FIRE, School of Engineering

    2015-12-15

    This paper deals with the modelling of a mechanically ventilated compartment fire which is a commonplace in nuclear fire scenarios. An advanced Computational Fluid Dynamics (CFD) field model with a wall conjugate heat transfer treatment is proposed. It simultaneously solves the compartment fire flow and the wall heat conduction. The flow solver is based on the Large Eddy Simulation (LES) based fire simulation solver FireFOAM within the frame of open source CFD code OpenFOAM {sup registered}. An extended eddy dissipation model is used to calculate the chemical reaction rate. A soot model based on the concept of smoke point height is employed to model the soot formation and oxidation. A finite volume method is adopted to model the radiative heat transfer. The ventilation flow is modelled by a simplified Bernoulli equation neglecting the detailed information on the ventilation system. The proposed model is validated against a single room fire test with forced mechanical ventilations. The predictions are in reasonably good agreement with experimental data.

  7. Measuring fire size in tunnels

    International Nuclear Information System (INIS)

    Guo, Xiaoping; Zhang, Qihui

    2013-01-01

    A new measure of fire size Q′ has been introduced in longitudinally ventilated tunnel as the ratio of flame height to the height of tunnel. The analysis in this article has shown that Q′ controls both the critical velocity and the maximum ceiling temperature in the tunnel. Before the fire flame reaches tunnel ceiling (Q′ 1.0), Fr approaches a constant value. This is also a well-known phenomenon in large tunnel fires. Tunnel ceiling temperature shows the opposite trend. Before the fire flame reaches the ceiling, it increases very slowly with the fire size. Once the flame has hit the ceiling of tunnel, temperature rises rapidly with Q′. The good agreement between the current prediction and three different sets of experimental data has demonstrated that the theory has correctly modelled the relation among the heat release rate of fire, ventilation flow and the height of tunnel. From design point of view, the theoretical maximum of critical velocity for a given tunnel can help to prevent oversized ventilation system. -- Highlights: • Fire sizing is an important safety measure in tunnel design. • New measure of fire size a function of HRR of fire, tunnel height and ventilation. • The measure can identify large and small fires. • The characteristics of different fire are consistent with observation in real fires

  8. Properties of flooding waves in vertical churn flow

    International Nuclear Information System (INIS)

    Wang, K.; Bai, B.; Yang, B.; Xie, C.

    2011-01-01

    It is more accurate to predict the critical heat flux (CHF) from the start of churn flow rather than the start of annular flow. High-speed photography has been employed for qualitative investigation of entrainment in vertical two-phase flow under churn flow condition. This paper mainly focuses on the evolution of the flooding waves close to the water inlet section and liquid distribution in the cross-section of tube. The properties of flooding wave such as frequency and amplitude have been obtained. (author)

  9. Entrainment to an auditory signal: Is attention involved?

    NARCIS (Netherlands)

    Kunert, R.; Jongman, S.R.

    2017-01-01

    Many natural auditory signals, including music and language, change periodically. The effect of such auditory rhythms on the brain is unclear however. One widely held view, dynamic attending theory, proposes that the attentional system entrains to the rhythm and increases attention at moments of

  10. Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed and Entrained-Flow Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Buitrago, Paula A. [Univ. of Utah, Salt Lake City, UT (United States); Morrill, Mike [Univ. of Utah, Salt Lake City, UT (United States); Lighty, JoAnn S. [Univ. of Utah, Salt Lake City, UT (United States); Silcox, Geoffrey D. [Univ. of Utah, Salt Lake City, UT (United States)

    2009-06-01

    This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO2, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO2 increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO2 concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO2. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO2, and NO2. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

  11. Modeling variable density turbulence in the wake of an air-entraining transom stern

    Science.gov (United States)

    Hendrickson, Kelli; Yue, Dick

    2015-11-01

    This work presents a priori testing of closure models for the incompressible highly-variable density turbulent (IHVDT) flows in the near wake region of a transom stern. This three-dimensional flow is comprised of convergent corner waves that originate from the body and collide on the ship center plane forming the ``rooster tail'' that then widens to form the divergent wave train. These violent free-surface flows and breaking waves are characterized by significant turbulent mass flux (TMF) at Atwood number At = (ρ2 -ρ1) / (ρ2 +ρ1) ~ 1 for which there is little guidance in turbulence closure modeling for the momentum and scalar transport along the wake. To whit, this work utilizes high-resolution simulations of the near wake of a canonical three-dimensional transom stern using conservative Volume-of-Fluid (cVOF), implicit Large Eddy Simulation (iLES), and Boundary Data Immersion Method (BDIM) to capture the turbulence and large scale air entrainment. Analysis of the simulation results across and along the wake for the TMF budget and turbulent anisotropy provide the physical basis of the development of multiphase turbulence closure models. Performance of isotropic and anisotropic turbulent mass flux closure models will be presented. Sponsored by the Office of Naval Research.

  12. A review of the interference of carbon containing fly ash with air entrainment in concrete

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard; Jensen, Anker Degn; Skjøth-Rasmussen, Martin Skov

    2008-01-01

    may interfere with air entraining admixtures (AEAs) added to enhance air entrainment in concrete in order to increase its workability and resistance toward freezing and thawing conditions. The problem has increased with implementation of low-NOx combustion technologies. This review presents the past...

  13. Formative flow in bedrock canyons

    Science.gov (United States)

    Venditti, J. G.; Kwoll, E.; Rennie, C. D.; Church, M. A.

    2017-12-01

    In alluvial channels, it is widely accepted that river channel configuration is set by a formative flow that represents a balance between the magnitude and frequency of flood flows. The formative flow is often considered to be one that is just capable of filling a river channel to the top of its banks. Flows much above this formative flow are thought to cause substantial sediment transport and rearrange the channel morphology to accommodate the larger flow. This idea has recently been extended to semi-alluvial channels where it has been shown that even with bedrock exposed, the flows rarely exceed that required to entrain the local sediment cover. What constitutes a formative flow in a bedrock canyon is not clear. By definition, canyons have rock walls and are typically incised vertically, removing the possibility of the walls being overtopped, as can occur in an alluvial channel at high flows. Canyons are laterally constrained, have deep scour pools and often have width to maximum depth ratios approaching 1, an order of magnitude lower than alluvial channels. In many canyons, there are a sequence of irregularly spaced scour pools. The bed may have intermittent or seasonal sediment cover, but during flood flows the sediment bed is entrained leaving a bare bedrock channel. It has been suggested that canyons cut into weak, well-jointed rock may adjust their morphology to the threshold for block plucking because the rock bed is labile during exceptionally large magnitude flows. However, this hypothesis does not apply to canyons cut into massive crystalline rock where abrasion is the dominant erosion process. Here, we argue that bedrock canyon morphology is adjusted to a characteristic flow structure developed in bedrock canyons. We show that the deeply scoured canyon floor is adjusted to a velocity inversion that is present at low flows, but gets stronger at high flows. The effect is to increase boundary shear stresses along the scour pool that forms in constricted

  14. Gas entrainment by one single French PWR spray, SARNET-2 spray benchmark

    Energy Technology Data Exchange (ETDEWEB)

    Malet, J., E-mail: jeanne.malet@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire, Saclay (France); Mimouni, S., E-mail: stephane.mimouni@edf.fr [Electricité de France, EDF MF2E, Chatou (France); Manzini, G., E-mail: giovanni.manzini@rse-web.it [RSE, Milano (Italy); Xiao, J., E-mail: jianjun.xiao@kit.edu [IKET, KIT, Karlsruhe (Germany); Vyskocil, L., E-mail: vyl@ujv.cz [UJV Rez (Czech Republic); Siccama, N.B., E-mail: siccama@nrg.eu [NRG, Safety and Power (Netherlands); Huhtanen, R., E-mail: risto.huhtanen@vtt.fi [VTT, PO Box 1000, FI-02044 VTT (Finland)

    2015-02-15

    Highlights: • This paper presents a benchmark performed in the frame of the SARNET-2 EU project. • It concerns momentum transfer between a PWR spray and the surrounding gas. • The entrained gas velocities can vary up to 100% from one code to another. • Simplified boundary conditions for sprays are generally used by the code users. • It is shown how these simplified conditions impact the gas entrainment. - Abstract: This paper presents a benchmark performed in the frame of the SARNET-2 EU project, dealing with momentum transfer between a real-scale PWR spray and the surrounding gas. It presents a description of the IRSN tests on the CALIST facility, the participating codes (8 contributions), code-experiment and code-to-code comparisons. It is found that droplet velocities are almost well calculated one meter below the spray nozzle, even if the spread of the spray is not recovered and the values of the entrained gas velocity vary up to 100% from one code to another. Concerning sensitivity analysis, several ‘simplifications’ have been made by the contributors, especially based on the boundary conditions applied at the location where droplets are injected. It is shown here that such simplifications influence droplet and entrained gas characteristics. The next step will be to translate these conclusions in terms of variables representative of interesting parameters for nuclear safety.

  15. Gas entrainment by one single French PWR spray, SARNET-2 spray benchmark

    International Nuclear Information System (INIS)

    Malet, J.; Mimouni, S.; Manzini, G.; Xiao, J.; Vyskocil, L.; Siccama, N.B.; Huhtanen, R.

    2015-01-01

    Highlights: • This paper presents a benchmark performed in the frame of the SARNET-2 EU project. • It concerns momentum transfer between a PWR spray and the surrounding gas. • The entrained gas velocities can vary up to 100% from one code to another. • Simplified boundary conditions for sprays are generally used by the code users. • It is shown how these simplified conditions impact the gas entrainment. - Abstract: This paper presents a benchmark performed in the frame of the SARNET-2 EU project, dealing with momentum transfer between a real-scale PWR spray and the surrounding gas. It presents a description of the IRSN tests on the CALIST facility, the participating codes (8 contributions), code-experiment and code-to-code comparisons. It is found that droplet velocities are almost well calculated one meter below the spray nozzle, even if the spread of the spray is not recovered and the values of the entrained gas velocity vary up to 100% from one code to another. Concerning sensitivity analysis, several ‘simplifications’ have been made by the contributors, especially based on the boundary conditions applied at the location where droplets are injected. It is shown here that such simplifications influence droplet and entrained gas characteristics. The next step will be to translate these conclusions in terms of variables representative of interesting parameters for nuclear safety

  16. Fish Oil Accelerates Diet-Induced Entrainment of the Mouse Peripheral Clock via GPR120

    Science.gov (United States)

    Itokawa, Misa; Nagahama, Hiroki; Ohtsu, Teiji; Furutani, Naoki; Kamagata, Mayo; Yang, Zhi-Hong; Hirasawa, Akira; Tahara, Yu; Shibata, Shigenobu

    2015-01-01

    The circadian peripheral clock is entrained by restricted feeding (RF) at a fixed time of day, and insulin secretion regulates RF-induced entrainment of the peripheral clock in mice. Thus, carbohydrate-rich food may be ideal for facilitating RF-induced entrainment, although the role of dietary oils in insulin secretion and RF-induced entrainment has not been described. The soybean oil component of standard mouse chow was substituted with fish or soybean oil containing docosahexaenoic acid (DHA) and/or eicosapentaenoic acid (EPA). Tuna oil (high DHA/EPA), menhaden oil (standard), and DHA/EPA dissolved in soybean oil increased insulin secretion and facilitated RF-induced phase shifts of the liver clock as represented by the bioluminescence rhythms of PER2::LUCIFERASE knock-in mice. In this model, insulin depletion blocked the effect of tuna oil and fish oil had no effect on mice deficient for GPR120, a polyunsaturated fatty acid receptor. These results suggest food containing fish oil or DHA/EPA is ideal for adjusting the peripheral clock. PMID:26161796

  17. A model study of mixing and entrainment in the horizontally evolving atmospheric convective boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Fedorovich, E.; Kaiser, R. [Univ. Karlsruhe, Inst. fuer Hydrologie und Wasserwirtschaft (Germany)

    1997-10-01

    We present results from a parallel wind-tunnel/large-eddy simulation (LES) model study of mixing and entrainment in the atmospheric convective boundary layer (CBL) longitudinally developing over a heated surface. The advection-type entrainment of warmer air from upper turbulence-free layers into the growing CBL has been investigated. Most of numerical and laboratory model studies of the CBL carried out so far dealt with another type of entrainment, namely the non-steady one, regarding the CBL growth as a non-stationary process. In the atmosphere, both types of the CBL development can take place, often being superimposed. (au)

  18. Granular flow in a rotating drum: Experiments and theory

    Science.gov (United States)

    Hung, C. Y.; Stark, C. P.; Capart, H.; Li, L.; Smith, B.; Grinspun, E.

    2015-12-01

    Erosion at the base of a debris flow fundamentally controls how large the flow will become and how far it will travel. Experimental observations of this important phenomenon are rather limited, and this lack has led theoretical treatments to making ad hoc assumptions about the basal process. In light of this, we carried out a combination of laboratory experiments and theoretical analysis of granular flow in a rotating drum, a canonical example of steady grain motion in which entrainment rates can be precisely controlled. Our main result is that basal sediment is entrained as the velocity profile adjusts to imbalance in the flow of kinetic energy.Our experimental apparatus consisted of a 40cm-diameter drum, 4cm-deep, half-filled with 2.3mm grains. Rotation rates varied from 1-70 rpm. We varied the effective scale by varying effective gravity from 1g to 70g on a geotechnical centrifuge. The field of grain motion was recorded using high-speed video and mapped using particle tracking velocimetry. In tandem we developed a depth-averaged theory using balance equations for mass, momentum and kinetic energy. We assumed a linearized GDR Midi granular rheology [da Cruz, 2005] and a Coulomb friction law along the sidewalls [Jop et al., 2005]. A scaling analysis of our equations yields a dimensionless "entrainment number" En, which neatly parametrizes the flow geometry in the drum for a wide range of variables, e.g., rotation rate and effective gravity. At low En, the flow profile is planar and kinetic energy is balanced locally in the flow layer. At high En, the flow profile is sigmoidal (yin-yang shaped) and the kinetic energy is dominated by longitudinal, streamwise transfer. We observe different scaling behavior under each of these flow regimes, e.g., between En and kinetic energy, surface slope and flow depth. Our theory correctly predicts their scaling exponents and the value of En at which the regime transition takes place. We are also able to make corrections for

  19. Laboratory simulations show diabatic heating drives cumulus-cloud evolution and entrainment

    Science.gov (United States)

    Narasimha, Roddam; Diwan, Sourabh Suhas; Duvvuri, Subrahmanyam; Sreenivas, K. R.; Bhat, G. S.

    2011-01-01

    Clouds are the largest source of uncertainty in climate science, and remain a weak link in modeling tropical circulation. A major challenge is to establish connections between particulate microphysics and macroscale turbulent dynamics in cumulus clouds. Here we address the issue from the latter standpoint. First we show how to create bench-scale flows that reproduce a variety of cumulus-cloud forms (including two genera and three species), and track complete cloud life cycles—e.g., from a “cauliflower” congestus to a dissipating fractus. The flow model used is a transient plume with volumetric diabatic heating scaled dynamically to simulate latent-heat release from phase changes in clouds. Laser-based diagnostics of steady plumes reveal Riehl–Malkus type protected cores. They also show that, unlike the constancy implied by early self-similar plume models, the diabatic heating raises the Taylor entrainment coefficient just above cloud base, depressing it at higher levels. This behavior is consistent with cloud-dilution rates found in recent numerical simulations of steady deep convection, and with aircraft-based observations of homogeneous mixing in clouds. In-cloud diabatic heating thus emerges as the key driver in cloud development, and could well provide a major link between microphysics and cloud-scale dynamics. PMID:21918112

  20. On the modelling of shallow turbidity flows

    Science.gov (United States)

    Liapidevskii, Valery Yu.; Dutykh, Denys; Gisclon, Marguerite

    2018-03-01

    In this study we investigate shallow turbidity density currents and underflows from mechanical point of view. We propose a simple hyperbolic model for such flows. On one hand, our model is based on very basic conservation principles. On the other hand, the turbulent nature of the flow is also taken into account through the energy dissipation mechanism. Moreover, the mixing with the pure water along with sediments entrainment and deposition processes are considered, which makes the problem dynamically interesting. One of the main advantages of our model is that it requires the specification of only two modeling parameters - the rate of turbulent dissipation and the rate of the pure water entrainment. Consequently, the resulting model turns out to be very simple and self-consistent. This model is validated against several experimental data and several special classes of solutions (such as travelling, self-similar and steady) are constructed. Unsteady simulations show that some special solutions are realized as asymptotic long time states of dynamic trajectories.

  1. A CFD Investigation on the Effect of the Air Entrainment in Breaking Wave Impacts on a Mono-Pile

    DEFF Research Database (Denmark)

    Tomaselli, Pietro; Christensen, Erik Damgaard

    2017-01-01

    In impacts of breaking waves on offshore structures, it is still not well-known how the air entrainment phenomenon affects the exerted loads. In this paper, a developed CFD solver capable of simulating the air entrainment process was employed to repro-duce an experimental investigation on the imp......In impacts of breaking waves on offshore structures, it is still not well-known how the air entrainment phenomenon affects the exerted loads. In this paper, a developed CFD solver capable of simulating the air entrainment process was employed to repro-duce an experimental investigation...... on the impact of a spilling wave against a circular cylinder. The exerted in-line force was computed with and without the inclusion of dispersed bubbles. Results showed that the magnitude of the computed force was affected when the entrainment of bubbles was simulated....

  2. Entraining the topology and the dynamics of a network of phase oscillators

    Science.gov (United States)

    Sendiña-Nadal, I.; Leyva, I.; Buldú, J. M.; Almendral, J. A.; Boccaletti, S.

    2009-04-01

    We show that the topology and dynamics of a network of unsynchronized Kuramoto oscillators can be simultaneously controlled by means of a forcing mechanism which yields a phase locking of the oscillators to that of an external pacemaker in connection with the reshaping of the network’s degree distribution. The entrainment mechanism is based on the addition, at regular time intervals, of unidirectional links from oscillators that follow the dynamics of a pacemaker to oscillators in the pristine graph whose phases hold a prescribed phase relationship. Such a dynamically based rule in the attachment process leads to the emergence of a power-law shape in the final degree distribution of the graph whenever the network is entrained to the dynamics of the pacemaker. We show that the arousal of a scale-free distribution in connection with the success of the entrainment process is a robust feature, characterizing different networks’ initial configurations and parameters.

  3. Influences of the chemical structure of entrainers on the activity coefficients in presence of biodiesel

    International Nuclear Information System (INIS)

    Mäder, A; Fleischmann, A; Fang, Ye; Krahl, J; Ruck, W

    2012-01-01

    In this work we analyzed the strength of the intermolecular forces between biodiesel and the entrainer and their influence on the entrainer's ability to interact with biodiesel. Furthermore we investigated the influence of the chemical structure of an entrainer to the interaction with biodiesel. For this purpose the activity coefficients γ ∞ at infinite dilution of acids, aldehydes, ketones and alcohols in biodiesel were measured with the method of headspace gas chromatography (HSGC). Short-chained acids showed the highest interaction of the analyzed entrainers caused by their ability to build hydrogen bonds with biodiesel. Increased chain length of the acids cause reduced interaction with biodiesel, which is mainly due to the higher obstruction of the acid molecule and therefore the reduced ability to build hydrogen bonds with biodiesel. Aldehydes, ketones and alcohols showed lower interaction with biodiesel compared to the acids. Longer-chained alcohols showed increased interaction with biodiesel due to the raised London Forces and an inductive +I effect of the molecule chain.

  4. COMPBRN III: a computer code for modeling compartment fires

    International Nuclear Information System (INIS)

    Ho, V.; Siu, N.; Apostolakis, G.; Flanagan, G.F.

    1986-07-01

    The computer code COMPBRN III deterministically models the behavior of compartment fires. This code is an improvement of the original COMPBRN codes. It employs a different air entrainment model and numerical scheme to estimate properties of the ceiling hot gas layer model. Moreover, COMPBRN III incorporates a number of improvements in shape factor calculations and error checking, which distinguish it from the COMPBRN II code. This report presents the ceiling hot gas layer model employed by COMPBRN III as well as several other modifications. Information necessary to run COMPBRN III, including descriptions of required input and resulting output, are also presented. Simulation of experiments and a sample problem are included to demonstrate the usage of the code. 37 figs., 46 refs

  5. Thermodynamic consequences of sodium leaks and fires in reactor containments

    International Nuclear Information System (INIS)

    Cherdron, W.; Jordan, S.

    1989-01-01

    In the technical and design concept of containment systems of sodium cooled breeder reactors due consideration must be given to the fact, that sodium penetration through leakages leads to sodium fires. The temperature and pressure rise caused by sodium fires makes it indispensable to analyze these accidents to be able to asses the safety of the whole system. To study the thermodynamic consequences of sodium leaks and fires, a long series of experiments on pool fires, spray fires and combined fires has been performed in the FAUNA-facility. In the pool fire experiments the pool area has been varied between 2 m 2 and 12 m 2 , with up to 500 kg of sodium at 500 deg. C inlet temperature. Burning rates between 20 and 40 kg Na/m 2 /h, depending on the particular conditions, can be stated for such types of fires. Combined fires, simulating a leakage through an insulation, have been investigated using a special sodium outlet 6 m above a 12 m 2 burning pan. The sodium flow ejection rate in these experiments covered the range of 50 up to 710 gr Na/sec, the maximum total amount of sodium released into the FAUNA vessel was 810 kg. The consequences of combined fires cover the range between pool fires and spray fires. The sodium spray fires were performed using a sodium spray system (150 liters of sodium at 500 deg. C and up to 6 bars overpressure), installed in the FAUNA containment, ejecting the sodium vertically upwards towards the impact plate at the top of the containment. In a series of experiments the spray nozzles have been varied from circular holes to sharp and rough edged slits, the flow rate covered the range from 0.8 kg Na/sec up to 56 Na/sec. It has been found that the nozzle design influences somewhat the course of the pressure increase, but the maximum overpressure is mainly determined by the sodium flow rate and the amount of sodium ejected. (author)

  6. The Importance of Stochastic Effects for Explaining Entrainment in the Zebrafish Circadian Clock

    Directory of Open Access Journals (Sweden)

    Raphaela Heussen

    2015-01-01

    Full Text Available The circadian clock plays a pivotal role in modulating physiological processes and has been implicated, either directly or indirectly, in a range of pathological states including cancer. Here we investigate how the circadian clock is entrained by external cues such as light. Working with zebrafish cell lines and combining light pulse experiments with simulation efforts focused on the role of synchronization effects, we find that even very modest doses of light exposure are sufficient to trigger some entrainment, whereby a higher light intensity or duration correlates with strength of the circadian signal. Moreover, we observe in the simulations that stochastic effects may be considered an essential feature of the circadian clock in order to explain the circadian signal decay in prolonged darkness, as well as light initiated resynchronization as a strong component of entrainment.

  7. Reflooding phase of the LOCA in PWRs. Part II: rewetting and liquid entrainment

    International Nuclear Information System (INIS)

    Elias, E.; Yadigaroglu, G.

    1978-01-01

    Surface rewetting and liquid-droplet entrainment play an important role in the analysis of the reflooding phase of the loss-of-coolant accident in pressurized-water reactors. The definitions and the various interpretations given to the rewetting temperature and the rewetting mechanisms of the fuel rods are discussed. Published models of the axial-conduction-controlled rewetting process include one-dimensional solutions in two axial regions, one-dimensional solutions in three axial regions with or without precursory cooling, one- and two-dimensional numerical-difference techniques using temperature-dependent heat-transfer coefficients, and analytical two-dimensional solutions. The basic physical assumptions and the numerical values assigned to the various parameters, as well as empirical rewetting correlations, are discussed. The physical mechanisms for liquid-droplet entrainment and analytical formulations of the critical gas velocity and of the droplet diameter at the onset of entrainment are reviewed

  8. Analysis of clad motion during a loss of flow (LOF) accident in a fast sodium cooled reactor

    International Nuclear Information System (INIS)

    Henkel, P.

    1985-10-01

    A new model describing clad motion during a Loss of Flow (LOF) accident in a Liquid Metal Cooled Fast (Breeder) Reactor (LMFBR) is presented. Its special features are Clad motion is treated within a fuel pin bundle. The bundle geometry is represented by an equivalent annular geometry which serves as the descriptional basis for the clad motion analysis; Several flow regimes are considered. These include a wave or film flow along the fuel pin surfaces as well as a drop flow within the coolant channels. A new entrainment criterion is successfully applied to describe the entrainment of molten cladding and the coolant flow is modelled as a two-dimensional, monstationary flow. Therefore, radial cross flows in a pin bundle can be calculated. Especially, thermal incoherency effects can be treated consistently. The analysis of clad motion in the two experiments STAR1 and STAR2 using the subsequently presented SANDCMOT model gives good agreement with the experimental data. (orig.) [de

  9. Foam formation in low expansion fire fighting equipment

    International Nuclear Information System (INIS)

    Rogers, Lucy Elizabeth

    2001-01-01

    This thesis describes an investigation into the foam generation mechanisms involved in producing foam from a low expansion fire fighting branchpipe. The investigation was carried out using scale models of branchpipes, and a high-speed video camera was used to study the formation of the foam. The experiments provided evidence of three possible methods of bubble formation within this type of system: Stage 1 - Mixing within the branchpipe; Stage 2 - Air entrainment and bubble growth during the flight of the jet; Stage 3 - Aeration produced from the collision of the high speed jet onto a surface. Each stage is described in detail and the mechanism which has the greatest effect on the expansion ratio of the foam produced has been determined. The relevance of these findings to the design of branchpipes is discussed. (author)

  10. Experimental Technique of Titanium Fire in Aero-engine

    Directory of Open Access Journals (Sweden)

    MI Guangbao

    2016-06-01

    Full Text Available Titanium fire is the typical catastrophic fault in the aero-engine. Aiming at the urgent demand for experimental technique of titanium fire from advanced high thrust-weight ratio aero-engine, the combustion technology and theory of titanium alloy based on friction oxygen concentration method (FOC were systematically studied. The evaluation method of fireproof property and the friction ignition model were built, and the fireproof mechanism was illustrated. By generalizing recent progress in experimental technique of titanium fire from three levels, including evolutionary rule, mechanism and prevention and control technology, the ideas and directions of experimental technique associated with the application research of titanium fire in the future were proposed, namely overall evaluation of fireproof property close to air flow environment of the aero-engine, prediction model of fireproof property and experimental verification of fireproof technique under the air flow environment of aero-engine. It is necessary to establish the prevention system of titanium fire in aero-engine, which contributes to the realization of "full titanium" in compressor and to the increase of high thrust-weight ratio.

  11. Fluidization mechanisms in slurry flow

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, C. S.

    1989-01-01

    There are two mechanisms by which heavy settling particles may be suspended in a horizontal slurry flow: (1) by particle-particle interactions (e.g. Bagnold dispersive stresses) and (2) by particle-fluid interactions (e.g. entrainment of the particles by turbulent eddies.) The purpose of this investigation is to determine to what extent each fluidization mechanism is active and the effect of the fluidization mechanism on the global properties of the slurry. The technique employs the understanding that the particles entrained in the turbulence of the fluid will appear as an increased hydrostatic head across the channel. This may be directly measured and can be related to the fraction of the mass of particles that are supported by fluid-particle forces. (The rest must therefore be supported by particle-particle forces.) 17 refs., 26 figs.

  12. Dispersion of the intrinsic neuronal periods affects the relationship of the entrainment range to the coupling strength in the suprachiasmatic nucleus

    Science.gov (United States)

    Gu, Changgui; Yang, Huijie; Wang, Man

    2017-11-01

    Living beings on the Earth are subjected to and entrained (synchronized) to the natural 24-h light-dark cycle. Interestingly, they can also be entrained to an external artificial cycle of non-24-h periods. The range of these periods is called the entrainment range and it differs among species. In mammals, the entrainment range is regulated by a main clock located in the suprachiasmatic nucleus (SCN) which is composed of 10 000 neurons in the brain. Previous works have found that the entrainment range depends on the cellular coupling strength in the SCN. In particular, the entrainment range decreases with the increase of the cellular coupling strength, provided that all the neuronal oscillators are identical. However, the SCN neurons differ in the intrinsic periods that follow a normal distribution in a range from 22 to 28 h. In the present study, taking the dispersion of the intrinsic neuronal periods into account, we examined the relationship between the entrainment range and the coupling strength. Results from numerical simulations and theoretical analyses both show that the relationship is altered to be paraboliclike if the intrinsic neuronal periods are nonidentical, and the maximal entrainment range is obtained with a suitable coupling strength. Our results shed light on the role of the cellular coupling in the entrainment ability of the SCN network.

  13. Value of a dual-polarized gap-filling radar in support of southern California post-fire debris-flow warnings

    Science.gov (United States)

    Jorgensen, David P.; Hanshaw, Maiana N.; Schmidt, Kevin M.; Laber, Jayme L; Staley, Dennis M.; Kean, Jason W.; Restrepo, Pedro J.

    2011-01-01

    A portable truck-mounted C-band Doppler weather radar was deployed to observe rainfall over the Station Fire burn area near Los Angeles, California, during the winter of 2009/10 to assist with debris-flow warning decisions. The deployments were a component of a joint NOAA–U.S. Geological Survey (USGS) research effort to improve definition of the rainfall conditions that trigger debris flows from steep topography within recent wildfire burn areas. A procedure was implemented to blend various dual-polarized estimators of precipitation (for radar observations taken below the freezing level) using threshold values for differential reflectivity and specific differential phase shift that improves the accuracy of the rainfall estimates over a specific burn area sited with terrestrial tipping-bucket rain gauges. The portable radar outperformed local Weather Surveillance Radar-1988 Doppler (WSR-88D) National Weather Service network radars in detecting rainfall capable of initiating post-fire runoff-generated debris flows. The network radars underestimated hourly precipitation totals by about 50%. Consistent with intensity–duration threshold curves determined from past debris-flow events in burned areas in Southern California, the portable radar-derived rainfall rates exceeded the empirical thresholds over a wider range of storm durations with a higher spatial resolution than local National Weather Service operational radars. Moreover, the truck-mounted C-band radar dual-polarimetric-derived estimates of rainfall intensity provided a better guide to the expected severity of debris-flow events, based on criteria derived from previous events using rain gauge data, than traditional radar-derived rainfall approaches using reflectivity–rainfall relationships for either the portable or operational network WSR-88D radars. Part of the reason for the improvement was due to siting the radar closer to the burn zone than the WSR-88Ds, but use of the dual-polarimetric variables

  14. Time-dependent effects of dim light at night on re-entrainment and masking of hamster activity rhythms.

    Science.gov (United States)

    Frank, David W; Evans, Jennifer A; Gorman, Michael R

    2010-04-01

    Bright light has been established as the most ubiquitous environmental cue that entrains circadian timing systems under natural conditions. Light equivalent in intensity to moonlight (dim nighttime illumination accelerated re-entrainment of hamster activity rhythms to 4-hour phase advances and delays of an otherwise standard laboratory photocycle. The purpose of this study was to determine if a sensitive period existed in the night during which dim illumination had a robust influence on speed of re-entrainment. Male Siberian hamsters were either exposed to dim light throughout the night, for half of the night, or not at all. Compared to dark nights, dim illumination throughout the entire night decreased by 29% the time for the midpoint of the active phase to re-entrain to a 4-hour phase advance and by 26% for a 4-hour delay. Acceleration of advances and delays were also achieved with 5 hours of dim light per night, but effects depended on whether dim light was present in the first half, second half, or first and last quarters of the night. Both during phase shifting and steady-state entrainment, partially lit nights also produced strong positive and negative masking effects, as well as entrainment aftereffects in constant darkness. Thus, even in the presence of a strong zeitgeber, light that might be encountered under a natural nighttime sky potently modulates the circadian timing system of hamsters.

  15. Characterization and evaluation of controls on post-fire streamflow response across western US watersheds

    Science.gov (United States)

    Saxe, Samuel; Hogue, Terri S.; Hay, Lauren

    2018-02-01

    This research investigates the impact of wildfires on watershed flow regimes, specifically focusing on evaluation of fire events within specified hydroclimatic regions in the western United States, and evaluating the impact of climate and geophysical variables on response. Eighty-two watersheds were identified with at least 10 years of continuous pre-fire daily streamflow records and 5 years of continuous post-fire daily flow records. Percent change in annual runoff ratio, low flows, high flows, peak flows, number of zero flow days, baseflow index, and Richards-Baker flashiness index were calculated for each watershed using pre- and post-fire periods. Independent variables were identified for each watershed and fire event, including topographic, vegetation, climate, burn severity, percent area burned, and soils data. Results show that low flows, high flows, and peak flows increase in the first 2 years following a wildfire and decrease over time. Relative response was used to scale response variables with the respective percent area of watershed burned in order to compare regional differences in watershed response. To account for variability in precipitation events, runoff ratio was used to compare runoff directly to PRISM precipitation estimates. To account for regional differences in climate patterns, watersheds were divided into nine regions, or clusters, through k-means clustering using climate data, and regression models were produced for watersheds grouped by total area burned. Watersheds in Cluster 9 (eastern California, western Nevada, Oregon) demonstrate a small negative response to observed flow regimes after fire. Cluster 8 watersheds (coastal California) display the greatest flow responses, typically within the first year following wildfire. Most other watersheds show a positive mean relative response. In addition, simple regression models show low correlation between percent watershed burned and streamflow response, implying that other watershed factors

  16. Response of fire detectors to different smokes

    International Nuclear Information System (INIS)

    Bjoerkman, J.; Keski-Rahkonen, O.

    1997-01-01

    The purpose of this work is to characterize the behavior of fire alarm systems based on smoke detectors on smoldering fires especially cable fires in nuclear power plants (NPP). Full-scale fire experiments were carried out in a laboratory designed according to the standard EN54-9. The laboratory was instrumented with additional equipment such as thermocouples and flow meters which are not used in standard fire sensitivity tests. This allows the results to be used as experimental data for validation tasks of numerical fire simulation computerized fluid dynamics (CFD)-codes. The ultimate goal of the research is to model theoretically smoldering and flaming cable fires, their smoke production, transfer of smoke to detectors, as well as the response of detectors and fire alarm systems to potential fires. This would allow the use of numerical fire simulation to predict fire hazards in different fire scenarios found important in PSA (probability safety assessment) of NPPs. This report concentrates on explaining full-scale fire experiments in the smoke sensitivity laboratory and experimental results from fire tests of detectors. Validation tasks with CFD-codes will be first carried out 'blind' without any idea about corresponding experimental results. Accordingly, the experimental results cannot be published in this report. (orig.)

  17. Experimental determination of the shipboard fire environment for simulated radioactive material packages

    International Nuclear Information System (INIS)

    Koski, J.A.; Bobbe, J.G.; Arviso, M.

    1997-03-01

    A series of eight fire tests with simulated radioactive material shipping containers aboard the test ship Mayo Lykes, a break-bulk freighter, is described. The tests simulate three basic types of fires: engine room fires, cargo fires and open pool fires. Detailed results from the tests include temperatures, heat fluxes and air flows measured during the fires. The first examination of the results indicates that shipboard fires are not significantly different from fires encountered in land transport. 13 refs., 15 figs., 11 tabs

  18. A balanced diet is necessary for proper entrainment signals of the mouse liver clock.

    Directory of Open Access Journals (Sweden)

    Akiko Hirao

    Full Text Available BACKGROUND: The peripheral circadian clock in mice is entrained not only by light-dark cycles but also by daily restricted feeding schedules. Behavioral and cell culture experiments suggest an increase in glucose level as a factor in such feeding-induced entrainment. For application of feeding-induced entrainment in humans, nutrient content and dietary variations should be considered. PRINCIPAL FINDING: To elucidate the food composition necessary for dietary entrainment, we examined whether complete or partial substitution of dietary nutrients affected phase shifts in liver clocks of mice. Compared with fasting mice or ad libitum fed mice, the liver bioluminescence rhythm advanced by 3-4 h on the middle day in Per2::luciferase knock-in mice that were administered a standard mouse diet, i.e. AIN-93M formula [0.6-0.85 g/10 g mouse BW] (composition: 14% casein, 47% cornstarch, 15% gelatinized cornstarch, 10% sugar, 4% soybean oil, and 10% other [fiber, vitamins, minerals, etc.], for 2 days. When each nutrient was tested alone (100% nutrient, an insignificant weak phase advance was found to be induced by cornstarch and soybean oil, but almost no phase advance was induced by gelatinized cornstarch, high-amylose cornstarch, glucose, sucrose, or casein. A combination of glucose and casein without oil, vitamin, or fiber caused a significant phase advance. When cornstarch in AIN-93M was substituted with glucose, sucrose, fructose, polydextrose, high-amylose cornstarch, or gelatinized cornstarch, the amplitude of phase advance paralleled the increase in blood glucose concentration. CONCLUSIONS: Our results strongly suggest the following: (1 balanced diets containing carbohydrates/sugars and proteins are good for restricted feeding-induced entrainment of the peripheral circadian clock and (2 a balanced diet that increases blood glucose, but not by sugar alone, is suitable for entrainment. These findings may assist in the development of dietary

  19. Fire behavior sensor package remote trigger design

    Science.gov (United States)

    Dan Jimenez; Jason Forthofer; James Reardon; Bret Butler

    2007-01-01

    Fire behavior characteristics (such as temperature, radiant and total heat flux, 2- and 3-dimensional velocities, and air flow) are extremely difficult to measure insitu. Although insitu sensor packages are capable of such measurements in realtime, it is also essential to acquire video documentation as a means of better understanding the fire behavior data recorded by...

  20. An improved liquid film model to predict the CHF based on the influence of churn flow

    International Nuclear Information System (INIS)

    Wang, Ke; Bai, Bofeng; Ma, Weimin

    2014-01-01

    The critical heat flux (CHF) for boiling crisis is one of the most important parameters in thermal management and safe operation of many engineering systems. Traditionally, the liquid film flow model for “dryout” mechanism shows a good prediction in heated annular two-phase flow. However, a general assumption that the initial entrained fraction at the onset of annular flow shows a lack of reasonable physical interpretation. Since the droplets have great momentum and the length of churn flow is short, the droplets in churn flow show an inevitable effect on the downstream annular flow. To address this, we considered the effect of churn flow and developed the original liquid film flow model in vertical upward flow by suggesting that calculation starts from the onset of churn flow rather than annular flow. The results indicated satisfactory predictions with the experimental data and the developed model provided a better understanding about the effect of flow pattern on the CHF prediction. - Highlights: •The general assumption of initial entrained fraction is unreasonable. •The droplets in churn flow show an inevitable effect on downstream annular flow. •The original liquid film flow model for prediction of CHF was developed. •The integration process was modified to start from the onset of churn flow

  1. Fire behavior simulation in Mediterranean forests using the minimum travel time algorithm

    Science.gov (United States)

    Kostas Kalabokidis; Palaiologos Palaiologou; Mark A. Finney

    2014-01-01

    Recent large wildfires in Greece exemplify the need for pre-fire burn probability assessment and possible landscape fire flow estimation to enhance fire planning and resource allocation. The Minimum Travel Time (MTT) algorithm, incorporated as FlamMap's version five module, provide valuable fire behavior functions, while enabling multi-core utilization for the...

  2. Construction program for a large superconducting MHD magnet system at the coal-fired flow facility

    International Nuclear Information System (INIS)

    Wang, S.T.; Genens, L.; Gonczy, J.; Ludwig, H.; Lieberg, M.; Kraft, E.; Gacek, D.; Huang, Y.C.; Chen, C.J.

    1980-01-01

    The Argonne National Laboratory has designed and is constructing a 6 T large aperture superconducting MHD magnet for use in the Coal-Fired Flow Facility (CFFF) at the University of Tennessee Space Institute (UTSI) at Tullahoma, Tennessee. The magnet system consists of the superconducting magnet, a magnet power supply, an integrated instrumentation for operation, control and protection, and a complete cryogenic facility including a CTI Model 2800 helium refrigerator/liquefier with two compressors, helium gas handling system and a 7500 liter liquid helium dewar. The complete system will be tested at Argonne, IL in 1981. The magnet design is reviewed, and the coil fabrication programs are described in detail

  3. Soot, organics, and ultrafine ash from air- and oxy-fired coal combustion

    KAUST Repository

    Andersen, Myrrha E.

    2016-10-19

    Pulverized bituminous coal was burned in a 10. W externally heated entrained flow furnace under air-combustion and three oxy-combustion inlet oxygen conditions (28, 32, and 36%). Experiments were designed to produce flames with practically relevant stoichiometric ratios (SR. =1.2-1.4) and constant residence times (2.3. s). Size-classified fly ash samples were collected, and measurements focused on the soot, elemental carbon (EC), and organic carbon (OC) composition of the total and ultrafine (<0.6. μm) fly ash. Results indicate that although the total fly ash carbon, as measured by loss on ignition, was always acceptably low (<2%) with all three oxy-combustion conditions lower than air-combustion, the ultrafine fly ash for both air-fired and oxy-fired combustion conditions consists primarily of carbonaceous material (50-95%). Carbonaceous components on particles <0.6. μm measured by a thermal optical method showed that large fractions (52-93%) consisted of OC rather than EC, as expected. This observation was supported by thermogravimetric analysis indicating that for the air, 28% oxy, and 32% oxy conditions, 14-71% of this material may be OC volatilizing between 100. C and 550. C with the remaining 29-86% being EC/soot. However, for the 36% oxy condition, OC may comprise over 90% of the ultrafine carbon with a much smaller EC/soot contribution. These data were interpreted by considering the effects of oxy-combustion on flame attachment, ignition delay, and soot oxidation of a bituminous coal, and the effects of these processes on OC and EC emissions. Flame aerodynamics and inlet oxidant composition may influence emissions of organic hazardous air pollutants (HAPs) from a bituminous coal. During oxy-coal combustion, judicious control of inlet oxygen concentration and placement may be used to minimize organic HAP and soot emissions.

  4. Activating and relaxing music entrains the speed of beat synchronized walking.

    Science.gov (United States)

    Leman, Marc; Moelants, Dirk; Varewyck, Matthias; Styns, Frederik; van Noorden, Leon; Martens, Jean-Pierre

    2013-01-01

    Inspired by a theory of embodied music cognition, we investigate whether music can entrain the speed of beat synchronized walking. If human walking is in synchrony with the beat and all musical stimuli have the same duration and the same tempo, then differences in walking speed can only be the result of music-induced differences in stride length, thus reflecting the vigor or physical strength of the movement. Participants walked in an open field in synchrony with the beat of 52 different musical stimuli all having a tempo of 130 beats per minute and a meter of 4 beats. The walking speed was measured as the walked distance during a time interval of 30 seconds. The results reveal that some music is 'activating' in the sense that it increases the speed, and some music is 'relaxing' in the sense that it decreases the speed, compared to the spontaneous walked speed in response to metronome stimuli. Participants are consistent in their observation of qualitative differences between the relaxing and activating musical stimuli. Using regression analysis, it was possible to set up a predictive model using only four sonic features that explain 60% of the variance. The sonic features capture variation in loudness and pitch patterns at periods of three, four and six beats, suggesting that expressive patterns in music are responsible for the effect. The mechanism may be attributed to an attentional shift, a subliminal audio-motor entrainment mechanism, or an arousal effect, but further study is needed to figure this out. Overall, the study supports the hypothesis that recurrent patterns of fluctuation affecting the binary meter strength of the music may entrain the vigor of the movement. The study opens up new perspectives for understanding the relationship between entrainment and expressiveness, with the possibility to develop applications that can be used in domains such as sports and physical rehabilitation.

  5. 46 CFR 28.820 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.820 Fire pumps, fire mains, fire hydrants, and fire hoses. (a) Each vessel must be equipped with a self-priming, power driven fire...

  6. Biological effects of simulated discharge plume entrainment at Indian Point Nuclear Power Station, Hudson River estuary, USA

    International Nuclear Information System (INIS)

    Lanza, G.R.; Lauer, G.J.; Ginn, T.C.; Storm, P.C.; Zubarik, L.; New York Univ., N.Y.

    1975-01-01

    Laboratory and field simulations of the discharge plume entrainment of phytoplankton, zooplankton and fish were carried out at the Indian Point Nuclear Station, Hudson River estuary, USA. Phytoplankton assemblages studied on two dates produced different response patterns measured as photosynthetic activity. Chlorophyll-a levels did not change following simulated entrainment. Possible explanations for the differences are discussed. The two abundant copepods Acartia tonsa and Eurytemorta affinis appear to tolerate exposure to discharge plume ΔT without adverse effects. Copepods subjected to plume entrainment may suffer considerable mortality during periods of condenser chlorination. In general, the amphipod Gammarus spp. did not appear to suffer significant mortality during simulated entrainment. Juvenile striped bass, Morone saxatilis, were not affected by simulated plume transit before and during plant condenser chlorination; however, a simulated ''worst possible case'' plume ΔT produced statistically significant moralities. (author)

  7. Two-component HLMC-gas flow instability and inhomogeneity phenomena in open-pool reactor

    International Nuclear Information System (INIS)

    Sergey I Shcherbakov

    2005-01-01

    Full text of publication follows: Consideration is being given to two-component gas-liquid flows with inhomogeneous gas content. The inhomogeneity of gas content over flow space can be caused by local mixing of gas and liquid, gas injection, gas-containing liquid jet penetration into the bulk of liquid without gas. The paper presents the computational results obtained using the direct non-stationary calculation with the TURBO-FLOW computer code. The results refer to flows near the liquid level, flows in downcomer gaps, collectors, elements with varying geometry (jet outlet into space, flow turn) for the pool-type reactors and experimental models. The following processes have been shown and discussed: formation of new liquid levels, entrainment of gas from the level, change in density composition of gas, flow stratification, effect of gas emergence rate and density convection on flow pattern. At gas phase transfer by liquid, two phenomena governing this transfer proceed: gas slip in liquid and density convection of non-uniformly aerated liquid. In horizontal flows, a vertical stratification of gas content always occurs. If the flow changes its direction to an upward one (collector at core inlet), the gas content maximum would be observed in channels nearest to the inlet. At the liquid level, the processes of gas separation from liquid and gas entrainment take place. The separation is a self-sustained process due to circulations arising near the level. The rate of gas entrainment is proportional to the rate of overflow and inversely proportional to the height of liquid level. At the downcomer region in case of its expansion, there occurs the instability of flow resulting in formation of liquid level and falling jet. The level is lower the more the gas content at inlet. The accumulation of gas occurs at sharp turns, encumbered regions (tube bundle), at all regions with upper (ceiling) constraints of flow. The flow instability being often observed in gas-liquid flows

  8. Fire protection in Angra-2 nuclear power plant. The use of fire protection collars on plastic piping systems

    International Nuclear Information System (INIS)

    Oliveira Segabinaze, R. de

    1994-01-01

    The object of this paper is to briefly the use of fire protection collars on plastic piping systems passing through wall and floor penetration. The fire protection collars consist of a stainless steel housing, in which the leading edges of two pivoting plates are in constant pressure contact with the pipe. In case of fire these plates react on the softened pipe with a guillotine action, thereby stopping the flow; within the housing a foam material expands to fill the space when subject to the heat of the fire. The piping project has to be modified to permit the fixing of the collars to walls and floor penetrations. (author). 2 refs, 9 figs

  9. Pool fires in a large scale ventilation system

    International Nuclear Information System (INIS)

    Smith, P.R.; Leslie, I.H.; Gregory, W.S.; White, B.

    1991-01-01

    A series of pool fire experiments was carried out in the Large Scale Flow Facility of the Mechanical Engineering Department at New Mexico State University. The various experiments burned alcohol, hydraulic cutting oil, kerosene, and a mixture of kerosene and tributylphosphate. Gas temperature and wall temperature measurements as a function of time were made throughout the 23.3m 3 burn compartment and the ducts of the ventilation system. The mass of the smoke particulate deposited upon the ventilation system 0.61m x 0.61m high efficiency particulate air filter for the hydraulic oil, kerosene, and kerosene-tributylphosphate mixture fires was measured using an in situ null balance. Significant increases in filter resistance were observed for all three fuels for burning time periods ranging from 10 to 30 minutes. This was found to be highly dependent upon initial ventilation system flow rate, fuel type, and flow configuration. The experimental results were compared to simulated results predicted by the Los Alamos National Laboratory FIRAC computer code. In general, the experimental and the computer results were in reasonable agreement, despite the fact that the fire compartment for the experiments was an insulated steel tank with 0.32 cm walls, while the compartment model FIRIN of FIRAC assumes 0.31 m thick concrete walls. This difference in configuration apparently caused FIRAC to consistently underpredict the measured temperatures in the fire compartment. The predicted deposition of soot proved to be insensitive to ventilation system flow rate, but the measured values showed flow rate dependence. However, predicted soot deposition was of the same order of magnitude as measured soot deposition

  10. Observational study of the relationship between entrainment rate and relative dispersion in deep convective clouds

    Science.gov (United States)

    Guo, Xiaohao; Lu, Chunsong; Zhao, Tianliang; Liu, Yangang; Zhang, Guang Jun; Luo, Shi

    2018-01-01

    This study investigates the influence of entrainment rate (λ) on relative dispersion (ε) of cloud droplet size distributions (CDSD) in the 99 growing precipitating deep convective clouds during TOGA-COARE. The results show that entrainment suppresses ε, which is opposite to the traditional understanding that entrainment-mixing broadens CDSD. To examine how the relationship between ε and λ is affected by droplets with different sizes, CDSDs are divided into three portions with droplet radius processes is developed to illustrate the possible scenarios entailing different relationships between ε and λ. The number concentration of small droplets and the degree of evaporation of small droplets are found to be key factors that shift the sign (i.e., positive or negative) of the ε-λ relationship.

  11. Characterization and evaluation of controls on post-fire streamflow response across western US watersheds

    Directory of Open Access Journals (Sweden)

    S. Saxe

    2018-02-01

    Full Text Available This research investigates the impact of wildfires on watershed flow regimes, specifically focusing on evaluation of fire events within specified hydroclimatic regions in the western United States, and evaluating the impact of climate and geophysical variables on response. Eighty-two watersheds were identified with at least 10 years of continuous pre-fire daily streamflow records and 5 years of continuous post-fire daily flow records. Percent change in annual runoff ratio, low flows, high flows, peak flows, number of zero flow days, baseflow index, and Richards–Baker flashiness index were calculated for each watershed using pre- and post-fire periods. Independent variables were identified for each watershed and fire event, including topographic, vegetation, climate, burn severity, percent area burned, and soils data. Results show that low flows, high flows, and peak flows increase in the first 2 years following a wildfire and decrease over time. Relative response was used to scale response variables with the respective percent area of watershed burned in order to compare regional differences in watershed response. To account for variability in precipitation events, runoff ratio was used to compare runoff directly to PRISM precipitation estimates. To account for regional differences in climate patterns, watersheds were divided into nine regions, or clusters, through k-means clustering using climate data, and regression models were produced for watersheds grouped by total area burned. Watersheds in Cluster 9 (eastern California, western Nevada, Oregon demonstrate a small negative response to observed flow regimes after fire. Cluster 8 watersheds (coastal California display the greatest flow responses, typically within the first year following wildfire. Most other watersheds show a positive mean relative response. In addition, simple regression models show low correlation between percent watershed burned and streamflow response, implying that

  12. Universal entrainment mechanism controls contact times with motile cells

    Science.gov (United States)

    Mathijssen, Arnold J. T. M.; Jeanneret, Raphaël; Polin, Marco

    2018-03-01

    Contact between particles and motile cells underpins a wide variety of biological processes, from nutrient capture and ligand binding to grazing, viral infection, and cell-cell communication. The window of opportunity for these interactions depends on the basic mechanism determining contact time, which is currently unknown. By combining experiments on three different species—Chlamydomonas reinhardtii, Tetraselmis subcordiforms, and Oxyrrhis marina—with simulations and analytical modeling, we show that the fundamental physical process regulating proximity to a swimming microorganism is hydrodynamic particle entrainment. The resulting distribution of contact times is derived within the framework of Taylor dispersion as a competition between advection by the cell surface and microparticle diffusion, and predicts the existence of an optimal tracer size that is also observed experimentally. Spatial organization of flagella, swimming speed, and swimmer and tracer size influence entrainment features and provide tradeoffs that may be tuned to optimize the estimated probabilities for microbial interactions like predation and infection.

  13. Biological evaluation of devices used for reducing entrainment and impingement losses at thermal power plants

    International Nuclear Information System (INIS)

    Cada, G.F.; Szluha, A.T.

    1978-01-01

    A preliminary survey of fish protection devices either in use or proposed for water intake structures was conducted for the purpose of assessing their potential for reducing impingement and entrainment. All the designs examined can be divided into two basic categories: behavioral screening systems and physical screening systems. The behavioral screening devices rely upon the ability of fish to sense artificial stimuli and respond by swimming away from hazardous areas. These systems are of little or no value in protecting planktonic fish eggs, larvae, and disoriented, heat-shocked, or lethargic adult fishes. Many of the physical screening devices, on the other hand, require the impingement of organisms against a screen before they can be removed from the intake system, thus subjecting survival. Some of the designs incorporate both behavioral and physical sceening concepts. Six devices were selected for further consideration based on their potential or demonstrated effectiveness in reducing impingement and entrainment losses at a variety of intake situations. The structures evaluated were modified vertical traveling screens, louvers, angled vertical traveling screens, horizontal traveling screens, center-flow screens, and wedge-wire screens. Since some of these intake structures represent new concepts, few laboratory or in situ biological studies have been carried out. For others, actual reductions in fish losses have been demonstrated. The design features and status of biological testing is discussed for each device, and an evaluation of their fish protection potential is presented

  14. On the pollutant removal, dispersion, and entrainment over two-dimensional idealized street canyons

    Science.gov (United States)

    Liu, Chun-Ho; Wong, Colman C. C.

    2014-01-01

    Pollutant dispersion over urban areas is not that well understood, in particular at the street canyon scale. This study is therefore conceived to examine how urban morphology modifies the pollutant removal, dispersion, and entrainment over urban areas. An idealized computational domain consisting of 12 two-dimensional (2D) identical street canyons of unity aspect ratio is employed. The large-eddy simulation (LES) is used to calculate the turbulent flows and pollutant transport in the urban boundary layer (UBL). An area source of uniform pollutant concentration is applied on the ground of the first street canyon. A close examination on the roof-level turbulence reveals patches of low-speed air masses in the streamwise flows and narrow high-speed downdrafts in the shear layer. Different from the flows over a smooth surface, the turbulence intensities are peaked near the top of the building roughness. The pollutant is rather uniformly distributed inside a street canyon but disperses quickly in the UBL over the buildings. Partitioning the vertical pollutant flux into its mean and turbulent components demystifies that the pollutant removal is mainly governed by turbulence. Whereas, mean wind carries pollutant into and out of a street canyon simultaneously. In addition to wind speed promotion, turbulent mixing is thus required to dilute the ground-level pollutants, which are then removed from the street canyon to the UBL. Atmospheric flows slow down rapidly after the leeward buildings, leading to updrafts carrying pollutants away from the street canyons (the basic pollutant removal mechanism).

  15. Cognitive performance as a zeitgeber: cognitive oscillators and cholinergic modulation of the SCN entrain circadian rhythms.

    Directory of Open Access Journals (Sweden)

    Howard J Gritton

    Full Text Available The suprachiasmatic nucleus (SCN is the primary circadian pacemaker in mammals that can synchronize or entrain to environmental cues. Although light exerts powerful influences on SCN output, other non-photic stimuli can modulate the SCN as well. We recently demonstrated that daily performance of a cognitive task requiring sustained periods of attentional effort that relies upon basal forebrain (BF cholinergic activity dramatically alters circadian rhythms in rats. In particular, normally nocturnal rats adopt a robust diurnal activity pattern that persists for several days in the absence of cognitive training. Although anatomical and pharmacological data from non-performing animals support a relationship between cholinergic signaling and circadian rhythms, little is known about how endogenous cholinergic signaling influences SCN function in behaving animals. Here we report that BF cholinergic projections to the SCN provide the principal signal allowing for the expression of cognitive entrainment in light-phase trained animals. We also reveal that oscillator(s outside of the SCN drive cognitive entrainment as daily timed cognitive training robustly entrains SCN-lesioned arrhythmic animals. Ablation of the SCN, however, resulted in significant impairments in task acquisition, indicating that SCN-mediated timekeeping benefits new learning and cognitive performance. Taken together, we conclude that cognition entrains non-photic oscillators, and cholinergic signaling to the SCN serves as a temporal timestamp attenuating SCN photic-driven rhythms, thereby permitting cognitive demands to modulate behavior.

  16. 46 CFR 28.315 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... After September 15, 1991, and That Operate With More Than 16 Individuals on Board § 28.315 Fire pumps, fire mains, fire hydrants, and fire hoses. (a) Each vessel 36 feet (11.8 meters) or more in length must...

  17. Liquid nitrogen fire extinguishing system test report

    International Nuclear Information System (INIS)

    Beidelman, J.A.

    1972-01-01

    The objective of this test series was to demonstrate the feasibility of using liquid nitrogen as a fire-extinguishing agent for certain types of metal fires. It was intended to provide data and experience appropriate to the design of a second series which will test the applicability of this technique to plutonium fires and which will develop more detailed operating information and permit more precise measurement of test parameters-oxygen depletion rates and equilibrium concentrations, temperature effects, and nitrogen pressures, flow rates, spray methods and patterns, etc. The test series was directed specifically toward extinguishment of metal fires occurring in well-confined areas and was not intended to be representative of any larger classification. Fires of several types were tested, e.g., magnesium, mixed magnesium and zirconium, sodium and cerium

  18. Pressure surge free fire water systems increase safety on offshore oil- and gas drilling platforms

    International Nuclear Information System (INIS)

    Carlsen, Randi

    2001-01-01

    The article describes a new fire water system for use on the oil- and gas drilling platforms that is characterized by improved start-up time and reduced energy consumption. Deluge valves are commonly used in fast large-flow fire water systems all over the world. During the test of a new fire water system on a platform a few years ago, a pipe near the living quarter suddenly ruptured due to an unexpected pressure surge thought to be impossible. It was caused by a weakness of the deluge valve. A better valve was needed and the 'UniqValve' was designed and manufactured. The UniqValve operates in cooperation with the fire pumps during start-up as it 'reads' the pressure variations of the water flow and corrects the water flow to the fire areas in less than a tenth of a second. The valve is now integrated in a modular system. The fire water unit is mounted in a container, which reduces cost and simplifies the placement of the fire water installation

  19. Research on the pyrolysis of hardwood in an entrained bed process development unit

    Energy Technology Data Exchange (ETDEWEB)

    Kovac, R.J.; Gorton, C.W.; Knight, J.A.; Newman, C.J.; O' Neil, D.J. (Georgia Inst. of Tech., Atlanta, GA (United States). Research Inst.)

    1991-08-01

    An atmospheric flash pyrolysis process, the Georgia Tech Entrained Flow Pyrolysis Process, for the production of liquid biofuels from oak hardwood is described. The development of the process began with bench-scale studies and a conceptual design in the 1978--1981 timeframe. Its development and successful demonstration through research on the pyrolysis of hardwood in an entrained bed process development unit (PDU), in the period of 1982--1989, is presented. Oil yields (dry basis) up to 60% were achieved in the 1.5 ton-per-day PDU, far exceeding the initial target/forecast of 40% oil yields. Experimental data, based on over forty runs under steady-state conditions, supported by material and energy balances of near-100% closures, have been used to establish a process model which indicates that oil yields well in excess of 60% (dry basis) can be achieved in a commercial reactor. Experimental results demonstrate a gross product thermal efficiency of 94% and a net product thermal efficiency of 72% or more; the highest values yet achieved with a large-scale biomass liquefaction process. A conceptual manufacturing process and an economic analysis for liquid biofuel production at 60% oil yield from a 200-TPD commercial plant is reported. The plant appears to be profitable at contemporary fuel costs of $21/barrel oil-equivalent. Total capital investment is estimated at under $2.5 million. A rate-of-return on investment of 39.4% and a pay-out period of 2.1 years has been estimated. The manufacturing cost of the combustible pyrolysis oil is $2.70 per gigajoule. 20 figs., 87 tabs.

  20. Conceptual design of heterogeneous azeotropic distillation process for ethanol dehydration using 1-butanol as entrainer

    OpenAIRE

    Paritta Prayoonyong

    2014-01-01

    The synthesis of a heterogeneous azeotropic distillation process for ethanol dehydration using 1-butanol as entrainer is presented. The residue curve map of the ethanol/water/1-butanol mixture is computationally generated using non-random twoliquid thermodynamic model. It is found that 1-butanol leads to a residue curve map topological structure different from that generated by typical entrainers used in ethanol dehydration. Synthesis...

  1. Oxygen-Fired CO{sub 2} Recycle for Application to Direct CO{sub 2} Capture form Coal-Fired Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Thomas Gale

    2010-09-26

    The Southern Research/Southern Company 1 MWth Pilot-Scale Coal-Fired Test Facility was successfully retrofit to fire in either the traditional air-fired mode or with 100% oxygen and recycled flue gas, with a fully integrated feedback and control system, including oxygen and recycled flue gas modulation during startup, transfer, and shutdown, safety and operational interlocks, and data acquisition. A MAXON Staged Oxygen Burner for Oxy-Coal Applications produced a stable flame over a significant range of firing turn-down, staging, and while firing five different U.S. coal types. The MAXON burner design produces lower flame temperatures than for air firing, which will enable (A) Safe operation, (B) Reduction of recycle flow without concern about furnace flame temperatures, and (C) May likely be affective at reducing slagging and fouling in the boiler and super heater at full-scale Power Plants. A CFD model of the Oxy-fired Combustion Research Facility (OCRF) was used to predict the flame geometry and temperatures in the OCRF and make a comparison with the air-fired case. The model predictions were consistent with the experimental data in showing that the MAXON burner fired with oxygen produced lower flame temperatures than the air-fired burner while firing with air.

  2. Entrainment phenomenon in gas–liquid two-phase flow: A review

    Indian Academy of Sciences (India)

    into four categories: (a) mathematical description of the phenomenon using ... dome, (b) the central depressed portion rises up due to momentum of liquid, ... vapour velocity gets carried all the way in the vapour flow, which happens to be the minimum ..... included the droplet collection on the plate coated with carbon layer at ...

  3. Conversational quality is affected by and reflected in prosodic entrainment

    DEFF Research Database (Denmark)

    Michalsky, Jan; Niebuhr, Oliver; Schoormann, Heike

    2018-01-01

    Prosodic entrainment is connected to various forms of communicative success. One possibility to assess successful communication in non-task-oriented everyday conversations is through the participants’ perception of conversational quality. In this study we investigate whether a speaker’s degree of...

  4. Geomorphic aspects of post-fire soil erosion - Schultz Fire 2010

    Science.gov (United States)

    Ann Youberg; Karen A. Koestner; Daniel G. Neary; Peter E. Koestner

    2011-01-01

    The summer of 2010 brought wildfires and near record monsoon rains to northern Arizona, USA, which generated debris flows and floods that caused extensive damage. The human-caused Schultz Fire on the Coconino National Forest northeast of Flagstaff was the largest wildfire in Arizona during 2010, burning 6,100 ha between June 20th and 30th. Ignited by an abandoned...

  5. Determination of dryout localization using a five-equation model of annular flow for boiling in minichannels

    OpenAIRE

    Wajs Jan; Mikielewicz Dariusz

    2017-01-01

    Detailed studies have suggested that the critical heat flux in the form of dryout in minichannels occurs when the combined effects of entrainment, deposition, and evaporation of the film make the film flow rate go gradually and smoothly to zero. Most approaches so far used the mass balance equation for the liquid film with appropriate formulations for the rate of deposition and entrainment respectively. It must be acknowledged that any discrepancy in determination of deposition and entrainmen...

  6. How can we reduce carbon in ash in firing pulverized coal

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, W. (and others)

    1992-12-01

    The article discusses solutions to the problem of reducing carbon in ash in firing pulverized coal. Suggested solutions to the problem include: reviewing air flow through the mills; examining the pulverizers for coal fineness variations; investigating air distribution in the burners; review dual-firing equations; examining the burners for slag build up; checking coal fineness is appropriate to the boiler; increasing air flow; and checking instrumentation. 2 figs., 1 photo.

  7. Holden gas-fired furnace baseline data. Revision 1

    International Nuclear Information System (INIS)

    Weatherspoon, K.A.

    1996-11-01

    The Holden gas-fired furnace is used in the enriched uranium recovery process to dry and combust small batches of combustibles. The ash is further processed. The furnace operates by allowing a short natural gas flame to burn over the face of a wall of porous fire brick on two sides of the furnace. Each firing wall uses two main burners and a pilot burner to heat the porous fire brick to a luminous glow. Regulators and orifice valves are used to provide a minimum gas pressure of 4 in. water column at a rate of approximately 1,450 scf/h to the burners. The gas flow rate was calculated by determining the gas flow appropriate for the instrumentation in the gas line. Observed flame length and vendor literature were used to calculate pilot burner gas consumption. Air for combustion, purging, and cooling is supplied by a single blower. Rough calculations of the air-flow distribution in piping entering the furnace show that air flow to the burners approximately agrees with the calculated natural gas flow. A simple on/off control loop is used to maintain a temperature of 1,000 F in the furnace chamber. Hoods and glove boxes provide contamination control during furnace loading and unloading and ash handling. Fan EF-120 exhausts the hoods, glove boxes, and furnace through filters to Stack 33. A review of the furnace safety shows that safety is ensured by design, interlocks, procedure, and a safety system. Recommendations for safety improvements include installation of both a timed ignition system and a combustible-gas monitor near the furnace. Contamination control in the area could be improved by redesigning the loading hood face and replacing worn gaskets throughout the system. 33 refs., 16 figs

  8. Numerical and experimental studies of droplet-gas flow

    Energy Technology Data Exchange (ETDEWEB)

    Joesang, Aage Ingebret

    2002-07-01

    This thesis considers droplet-gas flow by the use of numerical methods and experimental verification. A commercial vane separator was studied both numerical and by experiment. In addition some efforts are put into the numerical analysis of cyclones. The experimental part contains detailed measurements of the flow field between a pair of vanes in a vane separator and droplet size measurements. LDA (Laser Doppler Anemometry) was used to measure the velocity in two dimensions and corresponding turbulence quantities. The results from the LDA measurements are considered to be of high quality and are compared to numerical results obtained from a CFD (Computational Fluid Dynamics) analysis. The simulation showed good agreement between the numerical and experimental results. Combinations of different turbulence models; the standard k-epsilon model and the Reynold Stress Mode, different schemes; first order and higher order scheme and different near wall treatment of the turbulence; the Law of the wall and the Two-Layer Zonal model were used in the simulations. The Reynold Stress Model together with a higher order scheme performed rather poorly. The recirculation in parts of the separator was overpredicted in this case. For the other cases the overall predictions are satisfactory. PDA (Phase Doppler Anemometry) measurements were used to study the changes in the droplet size distribution through the vane separator. The PDA measurements show that smaller droplets are found at the outlet than present at the inlet. In the literature there exists different mechanisms for explaining the re-entrainment and generation of new droplets. The re-entrainments mechanisms are divided into four groups where droplet-droplet interaction, droplet break-up, splashing of impinging droplet and re-entrainment from the film are defined as the groups of re-entrainment mechanisms. Models for these groups are found in the literature and these models are tested for re-entrainment using the operational

  9. Program determines two-phase flow

    International Nuclear Information System (INIS)

    Yamashiro, C.E.; Espiell, L.G.S.; Farina, I.H.

    1986-01-01

    When a mixture of a gas and a liquid flows along a horizontal pipe, it is possible to have up to seven different flow patterns. These flow patterns are: 1. Dispersed. When nearly all the liquid is entrained as spray by the gas; 2. Annular. The liquid forms a film around the inside wall of the pipe, and the gas flows at a high velocity as a central core; 3. Bubble. Bubbles of gas move along at about the same velocity as the liquid; 4. Stratified. The liquid flows along the bottom of the pipe and the gas flows above over a smooth gas-liquid interface; 5. Wave. Is similar to stratified except the interface is disturbed by waves moving in the direction of flow; 6. Slug. Waves are picked up periodically in the form of frothy slugs that move at a much greater velocity than the average liquid velocity; 7. Plug. Alternate plugs of liquid and gas move along the pipe

  10. Pipeline oil fire detection with MODIS active fire products

    Science.gov (United States)

    Ogungbuyi, M. G.; Martinez, P.; Eckardt, F. D.

    2017-12-01

    We investigate 85 129 MODIS satellite active fire events from 2007 to 2015 in the Niger Delta of Nigeria. The region is the oil base for Nigerian economy and the hub of oil exploration where oil facilities (i.e. flowlines, flow stations, trunklines, oil wells and oil fields) are domiciled, and from where crude oil and refined products are transported to different Nigerian locations through a network of pipeline systems. Pipeline and other oil facilities are consistently susceptible to oil leaks due to operational or maintenance error, and by acts of deliberate sabotage of the pipeline equipment which often result in explosions and fire outbreaks. We used ground oil spill reports obtained from the National Oil Spill Detection and Response Agency (NOSDRA) database (see www.oilspillmonitor.ng) to validate MODIS satellite data. NOSDRA database shows an estimate of 10 000 spill events from 2007 - 2015. The spill events were filtered to include largest spills by volume and events occurring only in the Niger Delta (i.e. 386 spills). By projecting both MODIS fire and spill as `input vector' layers with `Points' geometry, and the Nigerian pipeline networks as `from vector' layers with `LineString' geometry in a geographical information system, we extracted the nearest MODIS events (i.e. 2192) closed to the pipelines by 1000m distance in spatial vector analysis. The extraction process that defined the nearest distance to the pipelines is based on the global practices of the Right of Way (ROW) in pipeline management that earmarked 30m strip of land to the pipeline. The KML files of the extracted fires in a Google map validated their source origin to be from oil facilities. Land cover mapping confirmed fire anomalies. The aim of the study is to propose a near-real-time monitoring of spill events along pipeline routes using 250 m spatial resolution of MODIS active fire detection sensor when such spills are accompanied by fire events in the study location.

  11. New theoretical model for two-phase flow discharged from stratified two-phase region through small break

    International Nuclear Information System (INIS)

    Yonomoto, Taisuke; Tasaka, Kanji

    1988-01-01

    A theoretical and experimental study was conducted to understand two-phase flow discharged from a stratified two-phase region through a small break. This problem is important for an analysis of a small break loss-of-coolant accident (LOCA) in a light water reactor (LWR). The present theoretical results show that a break quality is a function of h/h b , where h is the elevation difference between a bulk water level in the upstream region and break and b the suffix for entrainment initiation. This result is consistent with existing eperimental results in literature. An air-water experiment was also conducted changing a break orientation as an experimental parameter to develop and assess the model. Comparisons between the model and the experimental results show that the present model can satisfactorily predict the flow rate and the quality at the break without using any adjusting constant when liquid entrainment occurs in a stratified two-phase region. When gas entrainment occurs, the experimental data are correlated well by using a single empirical constant. (author)

  12. Methanol production via pressurized entrained flow biomass gasification – Techno-economic comparison of integrated vs. stand-alone production

    International Nuclear Information System (INIS)

    Andersson, Jim; Lundgren, Joakim; Marklund, Magnus

    2014-01-01

    The main objective with this work was to investigate techno-economically the opportunity for integrated gasification-based biomass-to-methanol production in an existing chemical pulp and paper mill. Three different system configurations using the pressurized entrained flow biomass gasification (PEBG) technology were studied, one stand-alone plant, one where the bark boiler in the mill was replaced by a PEBG unit and one with a co-integration of a black liquor gasifier operated in parallel with a PEBG unit. The cases were analysed in terms of overall energy efficiency (calculated as electricity-equivalents) and process economics. The economics was assessed under the current as well as possible future energy market conditions. An economic policy support was found to be necessary to make the methanol production competitive under all market scenarios. In a future energy market, integrating a PEBG unit to replace the bark boiler was the most beneficial case from an economic point of view. In this case the methanol production cost was reduced in the range of 11–18 Euro per MWh compared to the stand-alone case. The overall plant efficiency increased approximately 7%-units compared to the original operation of the mill and the non-integrated stand-alone case. In the case with co-integration of the two parallel gasifiers, an equal increase of the system efficiency was achieved, but the economic benefit was not as apparent. Under similar conditions as the current market and when methanol was sold to replace fossil gasoline, co-integration of the two parallel gasifiers was the best alternative based on received IRR. - Highlights: • Techno-economic results regarding integration of methanol synthesis processes in a pulp and paper mill are presented. • The overall energy efficiency increases in integrated methanol production systems compared to stand-alone production units. • The economics of the integrated system improves compared to stand-alone alternatives. • Tax

  13. Effective deep brain stimulation suppresses low frequency network oscillations in the basal ganglia by regularizing neural firing patterns

    Science.gov (United States)

    McConnell, George C.; So, Rosa Q.; Hilliard, Justin D; Lopomo, Paola; Grill, Warren M.

    2012-01-01

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for the motor symptoms of Parkinson’s disease (PD). The effects of DBS depend strongly on stimulation frequency: high frequencies (>90Hz) improve motor symptoms, while low frequencies (basal ganglia were studied in the unilateral 6-hydroxydopamine lesioned rat model of PD. Only high frequency DBS reversed motor symptoms and the effectiveness of DBS depended strongly on stimulation frequency in a manner reminiscent of its clinical effects in persons with PD. Quantification of single-unit activity in the globus pallidus externa (GPe) and substantia nigra reticulata (SNr) revealed that high frequency DBS, but not low frequency DBS, reduced pathological low frequency oscillations (~9Hz) and entrained neurons to fire at the stimulation frequency. Similarly, the coherence between simultaneously recorded pairs of neurons within and across GPe and SNr shifted from the pathological low frequency band to the stimulation frequency during high frequency DBS, but not during low frequency DBS. The changes in firing patterns in basal ganglia neurons were not correlated with changes in firing rate. These results indicate that high frequency DBS is more effective than low frequency DBS, not as a result of changes in firing rate, but rather due to its ability to replace pathological low frequency network oscillations with a regularized pattern of neuronal firing. PMID:23136407

  14. Effective deep brain stimulation suppresses low-frequency network oscillations in the basal ganglia by regularizing neural firing patterns.

    Science.gov (United States)

    McConnell, George C; So, Rosa Q; Hilliard, Justin D; Lopomo, Paola; Grill, Warren M

    2012-11-07

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for the motor symptoms of Parkinson's disease (PD). The effects of DBS depend strongly on stimulation frequency: high frequencies (>90 Hz) improve motor symptoms, while low frequencies (basal ganglia were studied in the unilateral 6-hydroxydopamine lesioned rat model of PD. Only high-frequency DBS reversed motor symptoms, and the effectiveness of DBS depended strongly on stimulation frequency in a manner reminiscent of its clinical effects in persons with PD. Quantification of single-unit activity in the globus pallidus externa (GPe) and substantia nigra reticulata (SNr) revealed that high-frequency DBS, but not low-frequency DBS, reduced pathological low-frequency oscillations (∼9 Hz) and entrained neurons to fire at the stimulation frequency. Similarly, the coherence between simultaneously recorded pairs of neurons within and across GPe and SNr shifted from the pathological low-frequency band to the stimulation frequency during high-frequency DBS, but not during low-frequency DBS. The changes in firing patterns in basal ganglia neurons were not correlated with changes in firing rate. These results indicate that high-frequency DBS is more effective than low-frequency DBS, not as a result of changes in firing rate, but rather due to its ability to replace pathological low-frequency network oscillations with a regularized pattern of neuronal firing.

  15. Extinguishing agent for combustible metal fires

    Science.gov (United States)

    Riley, John F.; Stauffer, Edgar Eugene

    1976-10-12

    A low chloride extinguishing agent for combustible metal fires comprising from substantially 75 to substantially 94 weight percent of sodium carbonate as the basic fire extinguishing material, from substantially 1 to substantially 5 weight percent of a water-repellent agent such as a metal stearate, from substantially 2 to substantially 10 weight percent of a flow promoting agent such as attapulgus clay, and from substantially 3 to substantially 15 weight percent of a polyamide resin as a crusting agent.

  16. Entraining IDyOT: timing in the information dynamics of thinking

    Directory of Open Access Journals (Sweden)

    Jamie Forth

    2016-10-01

    Full Text Available We present a novel hypothetical account of entrainment in music and language, in context of the Information Dynamics of Thinking model, IDyOT. The extended model affords an alternative view of entrainment, and its companion term, pulse, from earlier accounts. The model is based on hiearchical, statistical prediction, modeling expectations of both what an event will be and when it will happen. As such,it constitutes a kind of predictive coding, with a particular novel hypothetical implementation. Here, we focus on the model’s mechanism for predicting when a perceptual event will happen, given an existing sequence of past events, which maybe musical or linguistic. We propose a range of tests to validate or falsify the model, at various different levels of abstraction, and argue that computational modelling in particular, and this model in particular, can offer a means of providing limited but useful evidence for evolutionary hypotheses.

  17. Entrainment of the Circadian Rhythm in Egg Hatching of the Crab Dyspanopeus sayi by Chemical Cues from Ovigerous Females.

    Science.gov (United States)

    Forward, Richard B; Sanchez, Kevin G; Riley, Paul P

    2016-02-01

    The subtidal crab Dyspanopeus sayi has a circadian rhythm in larval release with a free-running period of 24.1 h. Under constant conditions, eggs hatch primarily in the 4-h interval after the time of sunset. The study tested the new model for entrainment in subtidal crabs, which proposes that the female perceives the environmental cycles and entrains the endogenous rhythm in the embryos. Results verified the model for D. sayi. Hatching by embryos collected from the field when they had not yet developed eye pigments, and were kept in constant conditions attached to their mother, exhibited the circadian hatching rhythm. Attached embryos could also be entrained to a new photoperiod in the laboratory before they developed eye pigments. Further, mature embryos removed from the female hatched rhythmically, indicating that a circadian rhythm resides in the embryos. However, if mature embryos with eye pigments were removed from the female and exposed to a new light-dark cycle, they could not be entrained to the new cycle; rather, they hatched according to the timing of the original light-dark cycle. Nevertheless, detached, mature embryos would entrain to a new light-dark cycle if they were in chemical, but not physical, contact with the female. Thus, the female perceives the light-dark cycle, and uses chemical cues to entrain the circadian rhythm of hatching by the embryos. © 2016 Marine Biological Laboratory.

  18. Assessing European wild fire vulnerability

    Science.gov (United States)

    Oehler, F.; Oliveira, S.; Barredo, J. I.; Camia, A.; Ayanz, J. San Miguel; Pettenella, D.; Mavsar, R.

    2012-04-01

    Wild fire vulnerability is a measure of potential socio-economic damage caused by a fire in a specific area. As such it is an important component of long-term fire risk management, helping policy-makers take informed decisions about adequate expenditures for fire prevention and suppression, and to target those regions at highest risk. This paper presents a first approach to assess wild fire vulnerability at the European level. A conservative approach was chosen that assesses the cost of restoring the previous land cover after a potential fire. Based on the CORINE Land Cover, a restoration cost was established for each land cover class at country level, and an average restoration time was assigned according to the recovery capacity of the land cover. The damage caused by fire was then assessed by discounting the cost of restoring the previous land cover over the restoration period. Three different vulnerability scenarios were considered assuming low, medium and high fire severity causing different levels of damage. Over Europe, the potential damage of wild land fires ranges from 10 - 13, 732 Euro*ha-1*yr-1 for low fire severity, 32 - 45,772 Euro*ha-1*yr-1 for medium fire severity and 54 - 77,812 Euro*ha-1*yr-1 for high fire severity. The least vulnerable are natural grasslands, moors and heathland and sclerophyllous vegetation, while the highest cost occurs for restoring broad-leaved forest. Preliminary validation comparing these estimates with official damage assessments for past fires shows reasonable results. The restoration cost approach allows for a straightforward, data extensive assessment of fire vulnerability at European level. A disadvantage is the inherent simplification of the evaluation procedure with the underestimation of non-markets goods and services. Thus, a second approach has been developed, valuing individual wild land goods and services and assessing their annual flow which is lost for a certain period of time in case of a fire event. However

  19. A Case Study of Two Computer Methods Used to Simulate Fires in Industrial Facilities

    National Research Council Canada - National Science Library

    Asselta, Christopher

    1997-01-01

    .... The arrangement of decaying organic matter may have been enough to generate a small fire. Conventional anthropologists argue that fire may have been first discovered in forest fires started by lightning, lava flows or other natural causes...

  20. Activating and relaxing music entrains the speed of beat synchronized walking.

    Directory of Open Access Journals (Sweden)

    Marc Leman

    Full Text Available Inspired by a theory of embodied music cognition, we investigate whether music can entrain the speed of beat synchronized walking. If human walking is in synchrony with the beat and all musical stimuli have the same duration and the same tempo, then differences in walking speed can only be the result of music-induced differences in stride length, thus reflecting the vigor or physical strength of the movement. Participants walked in an open field in synchrony with the beat of 52 different musical stimuli all having a tempo of 130 beats per minute and a meter of 4 beats. The walking speed was measured as the walked distance during a time interval of 30 seconds. The results reveal that some music is 'activating' in the sense that it increases the speed, and some music is 'relaxing' in the sense that it decreases the speed, compared to the spontaneous walked speed in response to metronome stimuli. Participants are consistent in their observation of qualitative differences between the relaxing and activating musical stimuli. Using regression analysis, it was possible to set up a predictive model using only four sonic features that explain 60% of the variance. The sonic features capture variation in loudness and pitch patterns at periods of three, four and six beats, suggesting that expressive patterns in music are responsible for the effect. The mechanism may be attributed to an attentional shift, a subliminal audio-motor entrainment mechanism, or an arousal effect, but further study is needed to figure this out. Overall, the study supports the hypothesis that recurrent patterns of fluctuation affecting the binary meter strength of the music may entrain the vigor of the movement. The study opens up new perspectives for understanding the relationship between entrainment and expressiveness, with the possibility to develop applications that can be used in domains such as sports and physical rehabilitation.

  1. Activating and Relaxing Music Entrains the Speed of Beat Synchronized Walking

    Science.gov (United States)

    Leman, Marc; Moelants, Dirk; Varewyck, Matthias; Styns, Frederik; van Noorden, Leon; Martens, Jean-Pierre

    2013-01-01

    Inspired by a theory of embodied music cognition, we investigate whether music can entrain the speed of beat synchronized walking. If human walking is in synchrony with the beat and all musical stimuli have the same duration and the same tempo, then differences in walking speed can only be the result of music-induced differences in stride length, thus reflecting the vigor or physical strength of the movement. Participants walked in an open field in synchrony with the beat of 52 different musical stimuli all having a tempo of 130 beats per minute and a meter of 4 beats. The walking speed was measured as the walked distance during a time interval of 30 seconds. The results reveal that some music is ‘activating’ in the sense that it increases the speed, and some music is ‘relaxing’ in the sense that it decreases the speed, compared to the spontaneous walked speed in response to metronome stimuli. Participants are consistent in their observation of qualitative differences between the relaxing and activating musical stimuli. Using regression analysis, it was possible to set up a predictive model using only four sonic features that explain 60% of the variance. The sonic features capture variation in loudness and pitch patterns at periods of three, four and six beats, suggesting that expressive patterns in music are responsible for the effect. The mechanism may be attributed to an attentional shift, a subliminal audio-motor entrainment mechanism, or an arousal effect, but further study is needed to figure this out. Overall, the study supports the hypothesis that recurrent patterns of fluctuation affecting the binary meter strength of the music may entrain the vigor of the movement. The study opens up new perspectives for understanding the relationship between entrainment and expressiveness, with the possibility to develop applications that can be used in domains such as sports and physical rehabilitation. PMID:23874469

  2. Co-firing Bosnian coals with woody biomass: Experimental studies on a laboratory-scale furnace and 110 MWe power unit

    Directory of Open Access Journals (Sweden)

    Smajevic Izet

    2012-01-01

    Full Text Available This paper presents the findings of research into cofiring two Bosnian cola types, brown coal and lignite, with woody biomass, in this case spruce sawdust. The aim of the research was to find the optimal blend of coal and sawdust that may be substituted for 100% coal in large coal-fired power stations in Bosnia and Herzegovina. Two groups of experimental tests were performed in this study: laboratory testing of co-firing and trial runs on a large-scale plant based on the laboratory research results. A laboratory experiment was carried out in an electrically heated and entrained pulverized-fuel flow furnace. Coal-sawdust blends of 93:7% by weight and 80:20% by weight were tested. Co-firing trials were conducted over a range of the following process variables: process temperature, excess air ratio and air distribution. Neither of the two coal-sawdust blends used produced any significant ash-related problems provided the blend volume was 7% by weight sawdust and the process temperature did not exceed 1250ºC. It was observed that in addition to the nitrogen content in the co-fired blend, the volatile content and particle size distribution of the mixture also influenced the level of NOx emissions. The brown coal-sawdust blend generated a further reduction of SO2 due to the higher sulphur capture rate than for coal alone. Based on and following the laboratory research findings, a trial run was carried out in a large-scale utility - the Kakanj power station, Unit 5 (110 MWe, using two mixtures; one in which 5%/wt and one in which 7%/wt of brown coal was replaced with sawdust. Compared to a reference firing process with 100% coal, these co-firing trials produced a more intensive redistribution of the alkaline components in the slag in the melting chamber, with a consequential beneficial effect on the deposition of ash on the superheater surfaces of the boiler. The outcome of the tests confirms the feasibility of using 7%wt of sawdust in combination

  3. Capabilities of current wildfire models when simulating topographical flow

    Science.gov (United States)

    Kochanski, A.; Jenkins, M.; Krueger, S. K.; McDermott, R.; Mell, W.

    2009-12-01

    Accurate predictions of the growth, spread and suppression of wild fires rely heavily on the correct prediction of the local wind conditions and the interactions between the fire and the local ambient airflow. Resolving local flows, often strongly affected by topographical features like hills, canyons and ridges, is a prerequisite for accurate simulation and prediction of fire behaviors. In this study, we present the results of high-resolution numerical simulations of the flow over a smooth hill, performed using (1) the NIST WFDS (WUI or Wildland-Urban-Interface version of the FDS or Fire Dynamic Simulator), and (2) the LES version of the NCAR Weather Research and Forecasting (WRF-LES) model. The WFDS model is in the initial stages of development for application to wind flow and fire spread over complex terrain. The focus of the talk is to assess how well simple topographical flow is represented by WRF-LES and the current version of WFDS. If sufficient progress has been made prior to the meeting then the importance of the discrepancies between the predicted and measured winds, in terms of simulated fire behavior, will be examined.

  4. Investigation of Balcony Plume Entrainment

    OpenAIRE

    Liu, F.; Nielsen, Peter V.; Heiselberg, Per; Brohus, Henrik; Li, B. Z.

    2009-01-01

    An investigation on the scenarios of the spill plume and its equation was presented in this paper. The study includes two aspects, i.e., the small-scale experiment and the numerical simulation. Two balcony spill plume models are assessed by comparing with the FDS (Fire Dynamic Simulation) and small scale model experiment results. Besides validating the spill model by experiments, the effect of different fire location on balcony plume is also discussed.The results show that the balcony equatio...

  5. Improved Design of PECS to reduce Flow Instability for EU-APR1400

    International Nuclear Information System (INIS)

    Hwang, Do Hyun; Lee, Keunsung

    2014-01-01

    For EU-APR1400, PECS (Passive Ex-vessel corium retaining and Cooling System), so-called core catcher, was adopted to keep the integrity of basemat in containment by preventing MCCI (Molten Core Concrete Interaction) through retaining core debris and cooling corium outside the reactor vessel. In this paper, the improved design of PECS is presented to increase coolability by reducing flow instability in the region of cooling channel. In this paper, flow instability analysis was carried out using CFD code to find out the most improved design of PECS, which is to increase coolability by reducing bubble entrainment in the region of cooling channel. The reduction of bubble entrainment in the downcomer facilitates higher mass flow rates in the downcomer. Among presented four designed for the downcomer of PECS, the superstep design shows the highest mass flow rate and the lowest gas holdup in the downcomer as well as in the cooling channel. Compared with the existing design, the elimination of the horizontal part and the addition of an extra space above the vertical entrance to the downcomer seem to help the separation of the vapor

  6. Fire on Stage

    Directory of Open Access Journals (Sweden)

    Nicholas Daly

    2017-12-01

    Full Text Available The nineteenth century theatre was fire-prone, to say the least. Across the century there were more than 1,100 major conflagrations in the world’s theatres, and countless smaller fires. In Great Britain almost every theatre seems to have burned down at some point. And yet, despite, or perhaps in part because of, this appalling record, fires were a staple feature of stage spectacle. Some plays placed them at the very centre of the entertainment, and as the century went on stage fires became more and more elaborate. Actual or simulated conflagrations were conjured up using a diverse array of technologies, some of them very simple, some depending on the most recent scientific discoveries. Here, I give a short tour of these technologies and their use in the plays of the period, and suggest some of the pleasures that they offered. While onstage flames could draw people in, offering an experience of immersive suspense, for instance, they also interrupted the dramatic flow, reminding audiences that they were seeing a performance, getting something for their money. To this extent, we are reminded that nineteenth-century drama provided something of a mixed and spectacular ‘theatre of attractions’, closer at times to the circus than to the novel.

  7. Groundwater controls on post-fire permafrost thaw: Water and energy balance effects

    OpenAIRE

    Rocha, Adrian; Mckenzie, Jeffrey; Lamontagne-Halle, Pierrick; Zipper, Samuel

    2018-01-01

    Fire frequency and severity is increasing in high latitude regions, with large impacts on the water and energy balances. However, the degree to which groundwater flow impacts the permafrost response to fire remains poorly understood and understudied. Here, we use the Anaktuvuk River Fire (Alaska, USA) as an archetypal example to investigate groundwater-permafrost interactions following fire. We identify key thermal and hydrologic parameters controlling permafrost and active layer response to ...

  8. An Investigation into the Mechanics of Windblown Dust Entrainment from Nickel Slag Surfaces Resembling Armoured Desert Pavements

    Science.gov (United States)

    Sanderson, Robert Steven

    The purpose of this thesis is to investigate the dynamics of PM 10 emission from a nickel slag stockpile that closely resembles a desert pavement in physical characteristics. In the field, it was observed that slag surfaces develop by natural processes into a well-armoured surface over some period of time. The surface then consists of two distinct layers; a surficial armour layer containing only non-erodible gravel and cobble-sized clasts, and an underlying dust-laden layer, which contains a wide size range of slag particles, from clay-sized to cobble-sized. This surficial armour layer protects the underlying fines from wind entrainment, at least under typical wind conditions; however, particle emissions still do occur under high wind speeds. The dynamics of particle entrainment from within these surfaces are investigated herein. It is shown that the dynamics of the boundary layer flow over these lag surfaces are influenced by the inherent roughness and permeability of the surficial armour layer, such that the flow resembles those observed over and within vegetation canopies, and those associated with permeable gravel-bed river channels. Restriction of air flow within the permeable surface produces a high-pressure zone within the pore spaces, resulting in a Kelvin-Helmholtz shear instability, which triggers coherent motions in the form of repeating burst-sweep cycles. Using Laser Doppler Anemometry (LDA), it is demonstrated that the lower boundary layer is characterized by both Q4 sweeping motions and Q2 bursting motions, while the upper boundary layer is dominated by Q2 bursts. Pore air motions within the slag material were measured using buried pressure ports. It is shown that the mean pressure gradient which forms within the slag material results in net upward displacement of air, or wind pumping. However, this net upward motion is a result of rapid oscillatory motions which are directly driven by coherent boundary layer motions. It is also demonstrated that

  9. Development and entrainment of the colonic circadian clock during ontogenesis

    Czech Academy of Sciences Publication Activity Database

    Polidarová, Lenka; Olejníková, Lucie; Paušlyová, Lucia; Sládek, Martin; Soták, Matúš; Pácha, Jiří; Sumová, Alena

    2014-01-01

    Roč. 306, č. 4 (2014), G346-G356 ISSN 0193-1857 R&D Projects: GA ČR(CZ) GAP303/12/1108 Institutional support: RVO:67985823 Keywords : circadian clock * clock gene * ontogenesis * circadian entrainment Subject RIV: ED - Physiology Impact factor: 3.798, year: 2014

  10. New tendencies in wildland fire simulation for understanding fire phenomena: An overview of the WFDS system capabilities in Mediterranean ecosystems

    Science.gov (United States)

    Pastor, E.; Tarragó, D.; Planas, E.

    2012-04-01

    Wildfire theoretical modeling endeavors predicting fire behavior characteristics, such as the rate of spread, the flames geometry and the energy released by the fire front by applying the physics and the chemistry laws that govern fire phenomena. Its ultimate aim is to help fire managers to improve fire prevention and suppression and hence reducing damage to population and protecting ecosystems. WFDS is a 3D computational fluid dynamics (CFD) model of a fire-driven flow. It is particularly appropriate for predicting the fire behaviour burning through the wildland-urban interface, since it is able to predict the fire behaviour in the intermix of vegetative and structural fuels that comprise the wildland urban interface. This model is not suitable for operational fire management yet due to computational costs constrains, but given the fact that it is open-source and that it has a detailed description of the fuels and of the combustion and heat transfer mechanisms it is currently a suitable system for research purposes. In this paper we present the most important characteristics of the WFDS simulation tool in terms of the models implemented, the input information required and the outputs that the simulator gives useful for understanding fire phenomena. We briefly discuss its advantages and opportunities through some simulation exercises of Mediterranean ecosystems.

  11. Examination of flame length for burning pulverized coal in laminar flow reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Dong; Kim, Gyu Bo; Chang, Young June; Song, Ju Hun; Jeon, Chung Hwan [Pusan National University, Busan (Korea, Republic of)

    2010-12-15

    Because there has been a recent increase in the use of low calorific coal compared to standard coal, it is crucial to control the char flame length governing the burning life-time of coal in a coal-fired utility boiler. The main objective of this study is to develop a simplified model that can theoretically predict the flame length for burning coal in a laboratory-scale entrained laminar flow reactor (LFR) system. The char burning behavior was experimentally observed when sub-bituminous pulverized coal was fed into the LFR under burning conditions similar to those in a real boiler: a heating rate of 1000 K/s, an oxygen molar fraction of 7.7 %, and reacting flue gas temperatures ranging from 1500 to 2000 K. By using the theoretical model developed in this study, the effect of particle size on the coal flame length was exclusively addressed. In this model, the effect of particle mass was eliminated to compare with the experimental result performed under a constant mass feeding of coal. Overall, the computed results for the coal flame length were in good agreement with the experimental data, particularly when the external oxygen diffusion effect was considered in the model

  12. Examination of flame length for burning pulverized coal in laminar flow reactor

    International Nuclear Information System (INIS)

    Kim, Jae Dong; Kim, Gyu Bo; Chang, Young June; Song, Ju Hun; Jeon, Chung Hwan

    2010-01-01

    Because there has been a recent increase in the use of low calorific coal compared to standard coal, it is crucial to control the char flame length governing the burning life-time of coal in a coal-fired utility boiler. The main objective of this study is to develop a simplified model that can theoretically predict the flame length for burning coal in a laboratory-scale entrained laminar flow reactor (LFR) system. The char burning behavior was experimentally observed when sub-bituminous pulverized coal was fed into the LFR under burning conditions similar to those in a real boiler: a heating rate of 1000 K/s, an oxygen molar fraction of 7.7 %, and reacting flue gas temperatures ranging from 1500 to 2000 K. By using the theoretical model developed in this study, the effect of particle size on the coal flame length was exclusively addressed. In this model, the effect of particle mass was eliminated to compare with the experimental result performed under a constant mass feeding of coal. Overall, the computed results for the coal flame length were in good agreement with the experimental data, particularly when the external oxygen diffusion effect was considered in the model

  13. Toward better assessment of tornado potential in typhoons: Significance of considering entrainment effects for CAPE

    Science.gov (United States)

    Sueki, Kenta; Niino, Hiroshi

    2016-12-01

    The characteristics of typhoons that spawned tornadoes (tornadic typhoons: TTs) in Japan from 1991 to 2013 were investigated by composite analysis using the Japanese 55 year Reanalysis and compared with those of typhoons that did not spawn tornadoes (nontornadic typhoons: NTs). We found that convective available potential energy (CAPE), which considers the effects of entrainment (entraining CAPE: E-CAPE), and storm-relative environmental helicity (SREH) are significantly large in the northeast quadrant of TTs where tornadoes frequently occur and that E-CAPE and SREH in that quadrant for TTs are larger than those for NTs. On the other hand, ordinary CAPE without entrainment does not account for the spatial distribution of tornado occurrences nor does it distinguish TTs from NTs. E-CAPE is sensitive to humidity in the midtroposphere; thus, it is effective for detecting a conditionally unstable layer up to about 550 hPa, which is distinctive of TTs.

  14. Using Neutron Radiography to Quantify Water Transport and the Degree of Saturation in Entrained Air Cement Based Mortar

    Science.gov (United States)

    Lucero, Catherine L.; Bentz, Dale P.; Hussey, Daniel S.; Jacobson, David L.; Weiss, W. Jason

    Air entrainment is commonly added to concrete to help in reducing the potential for freeze thaw damage. It is hypothesized that the entrained air voids remain unsaturated or partially saturated long after the smaller pores fill with water. Small gel and capillary pores in the cement matrix fill quickly on exposure to water, but larger pores (entrapped and entrained air voids) require longer times or other methods to achieve saturation. As such, it is important to quantitatively determine the water content and degree of saturation in air entrained cementitious materials. In order to further investigate properties of cement-based mortar, a model based on Beer's Law has been developed to interpret neutron radiographs. This model is a powerful tool for analyzing images acquired from neutron radiography. A mortar with a known volume of aggregate, water to cement ratio and degree of hydration can be imaged and the degree of saturation can be estimated.

  15. Debris flows: behavior and hazard assessment

    Science.gov (United States)

    Iverson, Richard M.

    2014-01-01

    Debris flows are water-laden masses of soil and fragmented rock that rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form lobate deposits when they spill onto valley floors. Because they have volumetric sediment concentrations that exceed 40 percent, maximum speeds that surpass 10 m/s, and sizes that can range up to ~109 m3, debris flows can denude slopes, bury floodplains, and devastate people and property. Computational models can accurately represent the physics of debris-flow initiation, motion and deposition by simulating evolution of flow mass and momentum while accounting for interactions of debris' solid and fluid constituents. The use of physically based models for hazard forecasting can be limited by imprecise knowledge of initial and boundary conditions and material properties, however. Therefore, empirical methods continue to play an important role in debris-flow hazard assessment.

  16. Characterization of exposure to byproducts from firing lead-free frangible ammunition in an enclosed, ventilated firing range.

    Science.gov (United States)

    Grabinski, Christin M; Methner, Mark M; Jackson, Jerimiah M; Moore, Alexander L; Flory, Laura E; Tilly, Trevor; Hussain, Saber M; Ott, Darrin K

    2017-06-01

    U.S. Air Force small arms firing ranges began using copper-based, lead-free frangible ammunition in the early 2000s due to environmental and health concerns related to the use of lead-based ammunition. Exposure assessments at these firing ranges have routinely detected chemicals and metals in amounts much lower than their mass-based occupational exposure limits, yet, instructors report work-related health concerns including respiratory distress, nausea, and headache. The objective of this study at one firing range was to characterize the aerosol emissions produced by weapons during firing events and evaluate the ventilation system's effectiveness in controlling instructor exposure to these emissions. The ventilation system was assessed by measuring the range static air pressure differential and the air velocity at the firing line. Air flow patterns were near the firing line. Instructor exposure was sampled using a filter-based air sampling method for metals and a wearable, real-time ultrafine particle counter. Area air sampling was simultaneously performed to characterize the particle size distribution, morphology, and composition. In the instructor's breathing zone, the airborne mass concentration of copper was low (range = free frangible ammunition. Using an ultrafine particle counter appears to be an alternative method of assessing ventilation effectiveness in removing ultrafine particulate produced during firing events.

  17. Effects of Temperature, Oxygen Partial Pressure, and Materials Selection on Slag Infiltration into Porous Refractories for Entrained-Flow Gasifiers

    Science.gov (United States)

    Kaneko, Tetsuya Kenneth

    The penetration rate of molten mineral contents (slag) from spent carbonaceous feedstock into porous ceramic-oxide refractory linings is a critical parameter in determining the lifecycle of integrated gasification combined cycle energy production plants. Refractory linings that withstand longer operation without interruption are desirable because they can mitigate consumable and maintenance costs. Although refractory degradation has been extensively studied for many other high-temperature industrial processes, this work focuses on the mechanisms that are unique to entrained-flow gasification systems. The use of unique feedstock mixtures, temperatures from 1450 °C to 1600 °C, and oxygen partial pressures from 10-7 atm to 10-9 atm pose engineering challenges in designing an optimal refractory material. Experimentation, characterization, and modeling show that gasifier slag infiltration into porous refractory is determined by interactions between the slag and the refractory that either form a physical barrier that impedes fluid flow or induce an increased fluid viscosity that decelerates the velocity of the fluid body. The viscosity of the slag is modified by the thermal profile of the refractory along the penetration direction as well as reactions between the slag and refractory that alter the chemistry, and thereby the thermo-physical properties of the fluid. Infiltration experiments reveal that the temperature gradient inherently present along the refractory lining limits penetration. A refractory in near-isothermal conditions demonstrates deeper slag penetration as compared to one that experiences a steeper thermal profile. The decrease in the local temperatures of the slag as it travels deeper into the refractory increases the viscosity of the fluid, which in turn slows the infiltration velocity of fluid body into the pores of the refractory microstructure. With feedstock mixtures that exhibit high iron-oxide concentrations, a transition-metal-oxide, the oxygen

  18. Evaluation method for two-phase flow and heat transfer in a feed-water heater

    International Nuclear Information System (INIS)

    Takamori, Kazuhide; Minato, Akihiko

    1993-01-01

    A multidimensional analysis code for two-phase flow using a two-fluid model was improved by taking into consideration the condensation heat transfer, film thickness, and film velocity, in order to develop an evaluation method for two-phase flow and heat transfer in a feed-water heater. The following results were obtained by a two-dimensional analysis of a feed-water heater for a power plant. (1) In the model, the film flowed downward in laminar flow due to gravity, with droplet entrainment and deposition. For evaluation of the film thickness, Fujii's equation was used in order to account for forced convection of steam flow. (2) Based on the former experimental data, the droplet deposition coefficient and droplet entrainment rate of liquid film were determined. When the ratio at which the liquid film directly flowed from an upper heat transfer tube to a lower heat transfer tube was 0.7, the calculated total heat transfer rate agreed with the measured value of 130 MW. (3) At the upper region of a heat transfer tube bundle where film thickness was thin, and at the outer region of a heat transfer tube bundle where steam velocity was high, the heat transfer rate was large. (author)

  19. Effect of Spacecraft Environmental Variables on the Flammability of Fire Resistant Fabrics

    Science.gov (United States)

    Osorio, A. F.; Fernandez-Pello, C.; Takahashi, S.; Rodriguez, J.; Urban, D. L.; Ruff, G.

    2012-01-01

    Fire resistant fabrics are used for firefighter, racecar drivers as well as astronaut suits. However, their fire resistant characteristics depend on the environment conditions and require study. Particularly important is the response of these fabrics to elevated oxygen concentration environments and radiant heat from a source such as an adjacent fire. In this work, experiments using two fire resistant fabrics were conducted to study the effect of oxygen concentration, external radiant flux and oxidizer flow velocity in concurrent flame spread. Results show that for a given fabric the minimum oxygen concentration for flame spread depends strongly on the magnitude of the external radiant flux. At increased oxygen concentrations the external radiant flux required for flame spread decreases. Oxidizer flow velocity influences the external radiant flux only when the convective heat flux from the flame has similar values to the external radiant flux. The results of this work provide further understanding of the flammability characteristics of fire resistant fabrics in environments similar to those of future spacecrafts.

  20. On-line ultrasonic gas entrainment monitor

    International Nuclear Information System (INIS)

    Day, C.K.; Pedersen, H.N.

    1978-01-01

    Apparatus employing ultrasonic energy for detecting and measuring the quantity of gas bubbles present in liquids being transported through pipes is described. An ultrasonic transducer is positioned along the longitudinal axis of a fluid duct, oriented to transmit acoustic energy radially of the duct around the circumference of the enclosure walls. The back-reflected energy is received centrally of the duct and interpreted as a measure of gas entrainment. One embodiment employs a conical reflector to direct the transmitted acoustic energy radially of the duct and redirect the reflected energy back to the transducer for reception. A modified embodiment employs a cylindrical ultrasonic transducer for this purpose

  1. Post-fire mulching and soil hydrological response

    Science.gov (United States)

    Jordán, Antonio; Zavala, Lorena M.; Gordillo-Rivero, Ángel J.; Muñoz-Rojas, Miriam; Keesstra, Saskia; Cerdà, Artemi

    2017-04-01

    In general, one of the major threats after a forest fire is the increased erosion. This can occur due to the erosive impact of rainfall after a drastic reduction of vegetation cover or to changes in soil surface properties that contribute to enhanced runoff flow. There is a consensus among researchers that one of the best ways to reduce this risk is to apply a mulch cover (straw, shredded wood or other materials) immediately after fire. In this study, we studied the effectiveness of various types of mulch materials for the reduction of runoff and soil loss during the first 3 years after a forest fire, in plots of different sizes, with special attention to water repellency and physical properties of the soil surface. In general, straw mulch reduced both runoff and erosion rate more than other treatments. However, the effect was much more important on larger plots. This may be due to specific processes and impacts on sediment connectivity and surface water flow. Therefore, the effect of the scale seems to be an important factor in the management of burnt soils.

  2. A data-driven approach for modeling post-fire debris-flow volumes and their uncertainty

    Science.gov (United States)

    Friedel, Michael J.

    2011-01-01

    This study demonstrates the novel application of genetic programming to evolve nonlinear post-fire debris-flow volume equations from variables associated with a data-driven conceptual model of the western United States. The search space is constrained using a multi-component objective function that simultaneously minimizes root-mean squared and unit errors for the evolution of fittest equations. An optimization technique is then used to estimate the limits of nonlinear prediction uncertainty associated with the debris-flow equations. In contrast to a published multiple linear regression three-variable equation, linking basin area with slopes greater or equal to 30 percent, burn severity characterized as area burned moderate plus high, and total storm rainfall, the data-driven approach discovers many nonlinear and several dimensionally consistent equations that are unbiased and have less prediction uncertainty. Of the nonlinear equations, the best performance (lowest prediction uncertainty) is achieved when using three variables: average basin slope, total burned area, and total storm rainfall. Further reduction in uncertainty is possible for the nonlinear equations when dimensional consistency is not a priority and by subsequently applying a gradient solver to the fittest solutions. The data-driven modeling approach can be applied to nonlinear multivariate problems in all fields of study.

  3. Large scale steam flow test: Pressure drop data and calculated pressure loss coefficients

    International Nuclear Information System (INIS)

    Meadows, J.B.; Spears, J.R.; Feder, A.R.; Moore, B.P.; Young, C.E.

    1993-12-01

    This report presents the result of large scale steam flow testing, 3 million to 7 million lbs/hr., conducted at approximate steam qualities of 25, 45, 70 and 100 percent (dry, saturated). It is concluded from the test data that reasonable estimates of piping component pressure loss coefficients for single phase flow in complex piping geometries can be calculated using available engineering literature. This includes the effects of nearby upstream and downstream components, compressibility, and internal obstructions, such as splitters, and ladder rungs on individual piping components. Despite expected uncertainties in the data resulting from the complexity of the piping geometry and two-phase flow, the test data support the conclusion that the predicted dry steam K-factors are accurate and provide useful insight into the effect of entrained liquid on the flow resistance. The K-factors calculated from the wet steam test data were compared to two-phase K-factors based on the Martinelli-Nelson pressure drop correlations. This comparison supports the concept of a two-phase multiplier for estimating the resistance of piping with liquid entrained into the flow. The test data in general appears to be reasonably consistent with the shape of a curve based on the Martinelli-Nelson correlation over the tested range of steam quality

  4. Fire simulation of the canister transfer and installation vehicle; Kapselin siirto- ja asennusajoneuvon palosimulointi

    Energy Technology Data Exchange (ETDEWEB)

    Peltokorpi, L. [Fortum Power and Heat Oy, Espoo (Finland)

    2012-12-15

    A pyrolysis model of the canister transfer and installation vehicle was developed and vehicle fires in the final disposal tunnel and in the central tunnel were simulated using the fire simulation program FDS (Fire Dynamics Simulator). For comparison, same vehicle fire was also simulated at conditions in which the fire remained as a fuel controlled during the whole simulation. The purpose of the fire simulations was to simulate the fire behaviour realistically taking into account for example the limitations coming from the lack of oxygen. The material parameters for the rubber were defined and the simulation models for the tyres developed by simulating the fire test of a front wheel loader rubber tyre done by SP Technical Research Institute of Sweden. In these simulations the most important phenomena were successfully brought out but the timing of the phenomena was difficult. The final values for the rubber material parameters were chosen so that the simulated fire behaviour was at least as intense as the measured one. In the vehicle fire simulations a hydraulic oil or diesel leak causing a pool fire size of 2 MW and 2 m{sup 2} was assumed. The pool fire was assumed to be located under the tyres of the SPMT (Self Propelled Modular Transporters) transporter. In each of the vehicle fire simulations only the tyres of the SPMT transporter were observed to be burning whereas the tyres of the trailer remained untouched. In the fuel controlled fire the maximum power was slightly under 10 MW which was reached in about 18 minutes. In the final disposal tunnel the growth of the fire was limited due to the lack of oxygen and the relatively fast air flows existing in the tunnel. Fast air flows caused the flame spreading to be limited to the certain directions. In the final disposal tunnel fire the maximum power was slightly over 7 MW which was reached about 8 minutes after the ignition. In the central tunnel there was no shortage of oxygen but the spread of the fire was limited

  5. Coexistence of Two Singularities in Dewetting Flows: Regularizing the Corner Tip

    NARCIS (Netherlands)

    Peters, I.R.; Snoeijer, Jacobus Hendrikus; Daerr, Adrian; Limat, Laurent

    2009-01-01

    Entrainment in wetting and dewetting flows often occurs through the formation of a corner with a very sharp tip. This corner singularity comes on top of the divergence of viscous stress near the contact line, which is only regularized at molecular scales. We investigate the fine structure of corners

  6. Validation of CTF Droplet Entrainment and Annular/Mist Closure Models using Riso Steam/Water Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wysocki, Aaron J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Salko, Robert K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-02-01

    This report summarizes the work done to validate the droplet entrainment and de-entrainment models as well as two-phase closure models in the CTF code by comparison with experimental data obtained at Riso National Laboratory. The Riso data included a series of over 250 steam/water experiments that were performed in both tube and annulus geometries over a range of various pressures and outlet qualities. Experimental conditions were set so that the majority of cases were in the annular/mist ow regime. Measurements included liquid lm ow rate, droplet ow rate, lm thickness, and two-phase pressure drop. CTF was used to model 180 of the tubular geometry cases, matching experimental geometry, outlet pressure, and outlet ow quality to experimental values. CTF results were compared to the experimental data at the outlet of the test section in terms of vapor and entrained liquid ow fractions, pressure drop per unit length, and liquid lm thickness. The entire process of generating CTF input decks, running cases, extracting data, and generating comparison plots was scripted using Python and Matplotlib for a completely automated validation process. All test cases and scripting tools have been committed to the COBRA-TF master repository and selected cases have been added to the continuous testing system to serve as regression tests. The dierences between the CTF- and experimentally-calculated ow fraction values were con- sistent with previous calculations by Wurtz, who applied the same entrainment correlation to the same data. It has been found that CTF's entrainment/de-entrainment predictive capability in the annular/mist ow regime for this particular facility is comparable to the licensed industry code, COBRAG. While lm and droplet predictions are generally good, it has been found that accuracy is diminished at lower ow qualities. This nding is consistent with the noted deciencies in the Wurtz entrainment model employed by CTF. The CTF predicted two-phase pressure drop in

  7. Heat transfer and flow structure evaluation of a synthetic jet emanating from a planar heat sink

    International Nuclear Information System (INIS)

    Manning, Paul; Persoons, Tim; Murray, Darina

    2014-01-01

    Direct impinging synthetic jets are a proven method for heat transfer enhancement, and have been subject to extensive research. However, despite the vast amount of research into direct synthetic jet impingement, there has been little research investigating the effects of a synthetic jet emanating from a heated surface, this forms the basis of the current research investigation. Both single and multiple orifices are integrated into a planar heat sink forming a synthetic jet, thus allowing the heat transfer enhancement and flow structures to be assessed. The heat transfer analysis highlighted that the multiple orifice synthetic jet resulted in the greatest heat transfer enhancements. The flow structures responsible for these enhancements were identified using a combination of flow visualisation, thermal imaging and thermal boundary layer analysis. The flow structure analysis identified that the synthetic jets decreased the thermal boundary layer thickness resulting in a more effective convective heat transfer process. Flow visualisation revealed entrainment of local air adjacent to the heated surface; this occurred from vortex roll-up at the surface of the heat sink and from the highly sheared jet flow. Furthermore, a secondary entrainment was identified which created a surface impingement effect. It is proposed that all three flow features enhance the heat transfer characteristics of the system.

  8. Physical and neural entrainment to rhythm: human sensorimotor coordination across tasks and effector systems

    Directory of Open Access Journals (Sweden)

    Jessica Marie Ross

    2014-08-01

    Full Text Available The human sensorimotor system can be readily entrained to environmental rhythms, through multiple sensory modalities. In this review, we provide an overview of theories of timekeeping that make this neuroentrainment possible. First, we present recent evidence that contests the assumptions made in classic timekeeper models. The role of state estimation, sensory feedback and movement parameters on the organization of sensorimotor timing are discussed in the context of recent experiments that examined simultaneous timing and force control. This discussion is extended to the study of coordinated multi-effector movements and how they may be entrained.

  9. Demonstration of Entrained Solids and Sr/TRU Removal Processes with Archived AN-107 Waste

    International Nuclear Information System (INIS)

    Hallen, R.T.; Brooks, K.P.; Jagoda, L.K.

    2000-01-01

    Archived AN-107 waste was used to evaluate entrained solids removal, Sr/TRU decontamination of supernatant, and Sr/TRU solids removal. Even though most of the entrained solids had been previously removed from the archived sample, the residual entrained solids rapidly fouled the filter element resulting in very poor filter performance. An attempt to run at higher pressure resulted in more fouling, and reduced filter performance. Filtration efforts to remove entrained solids were abandoned and the waste was treated for Sr/TRU removal with the entrained solids present. The new processing scheme for Sr/TRU removal involving precipitation by added strontium and permanganate worked well. The decontamination factors for Sr and TRU components were significantly greater than the ILAW DF requirements for higher reagent concentrations of 1M hydroxide, 0.075M Sr, and 0.05M permanganate and lower reagent concentrations of 0.8M hydroxide, 0.05M Sr, and 0.03M permanganate. These results support the use of lower concentration of reagent additions in future tests. Optimization studies should be conducted to examine the reduction in added hydroxide from 1M to 0.5 M, reduction of Sr from 0.075M to 0.05M, and reduction in permanganate from 0.05M to 0.03M and the impact this reduction has on filtration performance with new samples from Tank AN-107. The combined entrained solids and Sr/TRU precipitate were successfully filtered in the single element, crossflow filtration unit. The filtrate flux was high, >0.1 gpm/ft 2 , at the initial test conditions of 53 psi and 11.2ft/s for the treated archived AN-107 sample. The filter flux rate dropped significantly with time as testing progressed and appears to be a result of shearing the agglomerated solids and fouling of the filter element by the resulting fine particles. The relatively low clean water flux rates obtained at the end of the test also indicate filter fouling. Chemical cleaning was required to restore clean water flux rates to pre

  10. Mine-fire diagnostics applied to the Carbondale, Pennsylvania mine-fire site. Rept. of Investigations/1992

    International Nuclear Information System (INIS)

    Kim, A.G.; Justin, T.R.; Miller, J.F.

    1992-01-01

    The U.S. Bureau of Mines applied its mine fire diagnostic method to an abandoned anthracite mine fire site in Carbondale, Lackawanna County, PA. The technique to locate fires in abandoned coal mines and coal refuse piles includes the determination of hydrocarbon concentrations in mine gases, the imposition of an underground gas flow direction, and use of a surface mapping method, to define heated and cold zones in underground coal strata. The heated zones at Carbondale were characterized by elevated methane concentrations. The results of 25 communication tests were analyzed to define 2 large (approximately 100 by 250 ft) and 5 small, isolated heated zones. An approximate correlation existed between the location of the heated zones and areas of anomalous snow melt. The correlation between the results of the diagnostic test and subsurface temperatures was not significant

  11. Flow Friction or Spontaneous Ignition?

    Science.gov (United States)

    Stoltzfus, Joel M.; Gallus, Timothy D.; Sparks, Kyle

    2012-01-01

    "Flow friction," a proposed ignition mechanism in oxygen systems, has proved elusive in attempts at experimental verification. In this paper, the literature regarding flow friction is reviewed and the experimental verification attempts are briefly discussed. Another ignition mechanism, a form of spontaneous combustion, is proposed as an explanation for at least some of the fire events that have been attributed to flow friction in the literature. In addition, the results of a failure analysis performed at NASA Johnson Space Center White Sands Test Facility are presented, and the observations indicate that spontaneous combustion was the most likely cause of the fire in this 2000 psig (14 MPa) oxygen-enriched system.

  12. Study of droplet entrainment from bubbling surface in a bubble column

    International Nuclear Information System (INIS)

    Ramirez de Santiago, M.

    1991-05-01

    In a bubble column droplets are ejected from the free surface by bubble bursting or splashing. Depending on their size, the droplets are partly carried away by the streaming gas or fall back to the bubbling surface by gravity force. Experiments have been carried out to determine the void fraction in the column by means of an optical probe. In the interfacial zone the bubble bursting process was captured with a high-speed video camera. Simultaneous measurements were made of size and velocity of droplets at several distances from the bubbling surface with a Phase-Doppler Anemometry. The bubble column can be divided into three regions: A lower zone with a flat profile of the local void fraction, a central zone where the flow regime is steady and an upper zone where the local void fraction grows rapidly. A two-parameter log-normal distribution function was proposed in order to describe the polydisperse distribution of droplet-size. Results were obtained concerning the entrainment, concentration, volume fraction and interfacial area of droplets. Finally, it was found that the turbulence intensity affects the droplet terminal velocity for droplets smaller than the Kolmogorov microscale [fr

  13. Dilution of aircraft exhaust and entrainment rates for trajectory box models

    Energy Technology Data Exchange (ETDEWEB)

    Gerz, T [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere; Kaercher, B [Muenchen Univ. (Germany). Lehrstuhl fuer Bioklimatologie und Immissionsforschung

    1998-12-31

    In order to match in-situ measured concentrations of NO and NO{sub 2} in the wake, dilution factors or entrainment rates have to be used which take into account that the largest fraction of the exhaust is captured by the wing tip vortices. This fraction defines the primary wake. Baroclinicity and turbulence detrains parts of it later into the secondary wake. Both wake regimes undergo different chemical and microphysical histories. The rates {omega} are determined at which ambient air becomes entrained into the primary and the secondary portion of the exhaust plume. Numerical simulations of the highly resolved wake is used of cruising aircraft under typical atmosphere conditions with and without ambient turbulence. The simulations are oriented on a case where exhaust and dynamical data behind an eastbound travelling B-747 aircraft have been collected in-situ over the North-Atlantic east of Ireland. (author) 7 refs.

  14. The mammalian circadian clock and its entrainment by stress and exercise.

    Science.gov (United States)

    Tahara, Yu; Aoyama, Shinya; Shibata, Shigenobu

    2017-01-01

    The mammalian circadian clock regulates day-night fluctuations in various physiological processes. The circadian clock consists of the central clock in the suprachiasmatic nucleus of the hypothalamus and peripheral clocks in peripheral tissues. External environmental cues, including light/dark cycles, food intake, stress, and exercise, provide important information for adjusting clock phases. This review focuses on stress and exercise as potent entrainment signals for both central and peripheral clocks, especially in regard to the timing of stimuli, types of stressors/exercises, and differences in the responses of rodents and humans. We suggest that the common signaling pathways of clock entrainment by stress and exercise involve sympathetic nervous activation and glucocorticoid release. Furthermore, we demonstrate that physiological responses to stress and exercise depend on time of day. Therefore, using exercise to maintain the circadian clock at an appropriate phase and amplitude might be effective for preventing obesity, diabetes, and cardiovascular disease.

  15. Dilution of aircraft exhaust and entrainment rates for trajectory box models

    Energy Technology Data Exchange (ETDEWEB)

    Gerz, T. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere; Kaercher, B. [Muenchen Univ. (Germany). Lehrstuhl fuer Bioklimatologie und Immissionsforschung

    1997-12-31

    In order to match in-situ measured concentrations of NO and NO{sub 2} in the wake, dilution factors or entrainment rates have to be used which take into account that the largest fraction of the exhaust is captured by the wing tip vortices. This fraction defines the primary wake. Baroclinicity and turbulence detrains parts of it later into the secondary wake. Both wake regimes undergo different chemical and microphysical histories. The rates {omega} are determined at which ambient air becomes entrained into the primary and the secondary portion of the exhaust plume. Numerical simulations of the highly resolved wake is used of cruising aircraft under typical atmosphere conditions with and without ambient turbulence. The simulations are oriented on a case where exhaust and dynamical data behind an eastbound travelling B-747 aircraft have been collected in-situ over the North-Atlantic east of Ireland. (author) 7 refs.

  16. The enigmatic ultra-long run-out of seafloor density driven flows

    Science.gov (United States)

    Dorrell, R. M.

    2017-12-01

    Dilute, particulate-laden, density-driven flows - turbidity currents - are a predominant mechanism for transporting sediment from source to sink in deep marine environments. These flows sculpt channels on the seafloor and, as evidenced by a wealth of bathymetric data, can travel for >1000km, forming some of the largest sedimentary landforms on the planet. For turbidity currents to travel such large dsitances, sediment must be self-maintained in suspension, i.e., be in a state of autosuspension. It has been shown that such self-maintained sediment suspensions can only occur whilst inertial forces are greater than gravitational forces, entailing supercritical flow. This conclusion is paradoxical, as inertia dominated flows rapidly entrain fluid, thereby thickening and slowing to become subcritical. However, current theory can only truly be applied to the proximal upper slope regions of seafloor channels where incised flows are fully confined. This contrasts with the distal reaches of long run out turbidity current systems, where the flow is only partially confined through self-channelization. Here it is shown that overspill of partially confined flow has a significant effect on the hydro- and morphodynamics of turbidity current systems. A new model is derived that shows that channel overspill acts to negate the effects of ambient fluid entrainment: a dynamic balance that limits increases in flow depth and maintains supercritical flow throughout the channel. In the new model mass, momentum and energy conservation is modulated by flow overspill onto channel banks, necessarily requiring description of the vertical structure of the flow. Analysis of continuously stratified steady state flow dynamics shows that the integration of overspill and stratification is necessary to enable maintained autosuspension and thus predict the ultra-long run-out of turbidity currents.

  17. A study for disaster prevention in the case of the underground fire

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bok Youn; Kang, Chang Hee; Jo, Young Do; Lim, Sang Taek [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1997-12-01

    There are three categories of possible disaster or hazard in workings where diesel equipment are operating. 1) Disasters by exhaust pollutants: The equipment specially designed for underground use are strongly recommended. Workings using diesel equipment should be properly ventilated all the time to maintain the gas concentration bellow the permissible level. The fume diluter is recommended as the most practical after treatment device in Korean mines. 2) Underground fire: The main cause of diesel fire is over heated engine and spillage of hydraulic liquid. Therefore, protecting the over heat of engine, using fire resistive hydraulic liquid and high flash point fuel is requested. Fuel and the other oils are recommended to be stored at surface. To protect the smoke return in case of underground fire, the ventilation velocity must be kept more than 1.5m/sec. The fire smoke starts to return on 1.5m/sec and stops to return on 2.0m/sec. The fire smoke flows through upper half of the tunnel and it`s temperature is 10 degrees higher than ventilation air flow. For taking an immediate measure on fire, keeping the updated simulation is essential matter. 3) Other disasters. (author). 9 tabs., 15 figs.

  18. Study of the parabolic and elliptic approaches validities for a turbulent co-flowing jet

    Directory of Open Access Journals (Sweden)

    Mahmoud Houda

    2012-01-01

    Full Text Available An axisymmetric turbulent jet discharged in a co-flowing stream was studied with the aid of parabolic and elliptic approaches. The simulations were performed with two in-house codes. Detailed comparisons of data show good agreement with the corresponding experiments; and different behaviors of jet dilution were found in initial region at different ranges of velocities ratios. It has been found that the two approaches give practically the same results for the velocities ratios Ru ≤ 1.5. Further from this value, the elliptic approach highlights the appearance of the fall velocity zone and that’s due to the presence of a trough low pressure. This fall velocity has not been detected by the parabolic approach and that’s due to the jet entrainment by the ambient flow. The intensity of this entrainment is directly related to the difference between the primary (jet and the secondary flow (co-flow. In fact, by increasing the velocities ratios Ru, the sucked flux by the outer stream becomes more important; the fall velocity intensifies and changes into a recirculation zone for Ru ≥ 5.

  19. Wildland fire limits subsequent fire occurrence

    Science.gov (United States)

    Sean A. Parks; Carol Miller; Lisa M. Holsinger; Scott Baggett; Benjamin J. Bird

    2016-01-01

    Several aspects of wildland fire are moderated by site- and landscape-level vegetation changes caused by previous fire, thereby creating a dynamic where one fire exerts a regulatory control on subsequent fire. For example, wildland fire has been shown to regulate the size and severity of subsequent fire. However, wildland fire has the potential to influence...

  20. Design and Development of Fire Gridding Platform Based on Internet of Things

    Directory of Open Access Journals (Sweden)

    Wei San-Xi

    2016-01-01

    Full Text Available This article describes the construction background about fire gridding platform, reviews the research and progress in fire Internet of Things and fire gridding. The platform includes perception / execution layer, field control layer, network layer, center platform layer and application layer, which provide a good bonding about site control and remote monitoring. This article supplies a detail design for the main functions of application and task flow of fire hazard investigation. At the same time, a digital management platform was developed.