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... bypasses control rod drives cylinders electromagnetic pumps fluid flow fluidic

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PMID:747753

International Nuclear Information System (INIS)

... coolants departure nucleate boiling fluid flow fluidic control devices fuel

Science.gov (United States)

... They comprise of a power model for the representation of the electric system, a fluid model that represents the cooling fluid flow, three layers of ...

CERN Document Server

Simulation approaches for nano-scale semiconductor devices

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PMID:534760

Science.gov (United States)

Not Available

Science.gov (United States)

Not Available

Science.gov (United States)

... of the cycle shows that the separation area ea. ... with suitable flow solvers based on the Reynolds ... AGARD 75th Fluid Dynamics Panel Meeting and ...

Energy Technology Data Exchange (ETDEWEB)

A flow pattern or flow regime is the characteristics spatial distribution of the phases of fluid in a duct. Since heat transfer and pressure drop are dependent on the characteristic distribution of the phases, it is necessary to describe flow patterns in an appropriate manner so that a hydrodynamic or heat transfer theory applicable to that pattern can be chosen. The objective of the present analysis is to create a flow regime map based on physical modeling of vapor/liquid interaction phenomena in a microgravity environment. In the present work, four basic flow patterns are defined: dispersed flow, stratified flow, slug flow, and annular flow. Fluid properties, liquid and vapor flow rates, and pipe size were chosen as the principal ...

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RODbaffle heat exchanger is a kind of shell-and-tube heat exchanger with eminent performance. Because of the characteristics of tube bundle support structure, fluid flow on shellside is longitudinal and periodical, and fluid flow is of symmetry in landscape orientation. According to the fluid flow characteristics on shellside and ignoring the impact of inlet, outlet and shell wall, a periodic flow unit duct was taken as the simplified model of the shellside to perform numerical simulation by using CFD code, FLUENT. It was found that the both errors in magnitude of the main fluid velocities and heat transfer coefficients between results of simulation and that of experiment or correlations are less than 10%, and the errors of pressure drop between simulation and correlation are no more than 20%. The detailed ...

International Nuclear Information System (INIS)

A technique was developed that permits fluid flow to be visualized even where the flow is completely shrouded by metal. The technique employs real-time neutron radiography, which is similar to x-ray radiography except a collimated beam of neutrons is used. Various combinations of neutron-opaque tracer materials were tested with neutron-transparent fluid. Neutron opaque tracers, such as solid particles, fluid droplets, and streaklines were imaged through metal walls as they convected in neutron-transparent ambient fluid. Visualization of bubbles/voids were evaluated for possible future applications. Surface-flow patterns were also imaged by using neutron-opaque tufts. These techniques were evaluated for image contrast, resolution, and the ability to accurately track fluid flow fields. The techniques ...

Science.gov (United States)

When induced by bottom heating in a horizontal fluid layer which is characterized by forced motion or solute stratification, buoyancy-driven flows may assume a variety of forms. The flows, which are examples of mixed or double-diffusive convection, can strongly influence heat tranfer or the entrainment of stratified fluid. General aspects of each form of convection are reviewed, and emphasis is placed on mixed convection in a horizontal rectangular channel and on double-diffusive convection due to thermally driven mixed-layer development in a solutally stratified fluids. Flow conditions are described, and experimental and theoretical results are presented for related heat-transfer and entrainment parameters.

Science.gov (United States)

rotor flow field in which the main rotor operates. The majority of ..... early separation predicted by their CFD code was ...... Airfoil, AGARD Fluid Dynamics Panel ...

Energy Technology Data Exchange (ETDEWEB)

Different calculated models are presented for turbulent break-off flows and their classification, reflecting the sequence of historical development. The study was done based on equations of viscous liquid of the Navier-Stokes type with development of special phenomenological models of turbulence which take into consideration real properties of the break-off flows based on simpler models of flow presented in the work. In order to calculate two-dimensional turbulent flows, a method of viscous-nonviscous interaction is used. It employs numerical solutions for nonviscous flow and integrated methods of calculating the dissipative region. This method can be extended for calculating the transonic break-off flows, and also break-off in an incompressible fluid when there is cavitation.

Energy Technology Data Exchange (ETDEWEB)

An approximate analysis based on the virtual work technique, which was used to determine the effect of fluid velocity on the response frequency of a simply supported pipe, resulted in the following conclusions: (1) the critical fluid velocity at which the system becomes statically unstable is 129.5 ft/s; (2) the natural frequency of the pipe decreases as the fluid velocity increases; (3) higher flow rates increase the dynamic coupling of the system, making it much more susceptible to external excitation; (4) as the critical frequency approaches zero and the fluid velocity approaches the critical value, the amplitude becomes greater (though in an actual pipe, damping effects will limit the amplitude somewhat); and (5) the virtual work technique is a convenient method for approximating solutions to most non-linear vibration problems, giving results that are satisfactory for ...

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The effect of transverse magnetic field parameter (Hartmann number, Ha) Reynolds number (Re) and Prandtl number (Pr) on the mixed convection flow past a semi-infinite vertical porous plate in a non-Darcian porous medium with variable viscosity and porosity, viscous dissipation and fluid-solid thermal conductivity ratio in the presence of plate transpiration (lateral mass flux) is investigated theoretically and numerically using Keller`s implicit finite difference scheme. It is shown that the Harmann number acts as a retarding force and increases the momentum boundary layer thickness, analogous to the flow against a positive pressure gradient, simultaneously decreasing local skin friction (shear stress). The heat transfer rate is however enhanced by the magnetic field (for positive values of the Eckert number) since the fluid is heated and temperature gradients become reduced between the ...

Energy Technology Data Exchange (ETDEWEB)

Applications, techniques, instrumentation, and interpretation of flow visualization are discussed. Methods of using flow visualization for the examination of combustion in furnaces, heat transfer with heat exchangers, and in fluid engines are explored, along with flow visualization in food processing, steel-casting, and process engineering. Further attention is given to pipe and channel flow, flow separation in laminar flow and around oscillating airfoils, wakes and vortices, supersonic flow and shock waves, and stratified flow and oceanography. The visualization of boundary layers is considered for various conditions, and applications for multiphase flow, rheology, and medical problems are detailed. Oil film, dry-surface coating, chemical, fluorescent, and minituft methods are ...

International Nuclear Information System (INIS)

A series of real-time, neutron radiography, experiments are ongoing at the Texas A and M Nuclear Science Center Reactor (NSCR). These tests determine the resolving capabilities for radiographic imaging of two phase water and air flow regimes through small diameter flow channels. Though both film and video radiographic imaging is available, the real-time video imaging was selected to capture the dynamic flow patterns with results that continue to improve. (author)

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This paper reports the results of an investigation into the vibration of functionally graded cylindrical shells with flowing fluid, embedded in an elastic medium, under mechanical and thermal loads. By considering rotary inertia, the first-order shear deformation theory (FSDT) and the fluid velocity potential, the dynamic equation of functionally graded cylindrical shells with flowing fluid is derived. Here, heat conduction equation along the thickness of the shell is applied to determine the temperature distribution and material properties are assumed to be graded distribution along the thickness direction according to a power-law in terms of the volume fractions of the constituents. The equations of eigenvalue problem are obtained by using a modal expansion method. In numerical examples, effects of material composition, thermal loading, static axial loading, ...

Science.gov (United States)

This paper deals with a mixed convection water flow in a horizontal rectangular duct, uniformly heated from one lateral vertical wall and thermally insulated elsewhere. The supplied heat flux induces a secondary flow, which structure is constituted of one longitudinal roll in the considered aspect ratio (? = 1.9), embedded into a return flow of possibly large stream wise extension (up to twenty channel heights). Such situation induces helicoidal trajectories for the fluid flow particles, which contributes to a heat transfer enhancement compared to purely forced convection flow.

British Library Electronic Table of Contents (United Kingdom)

An impingement jet system was used to study flow-assisted corrosion (FAC) of 3003 aluminum (Al) alloy in ethylene glycol-water solutions that simulates the automotive coolant by corrosion potential and electrochemical impedance spectroscopy (EIS) measurements as well as computational fluid dynamics (CFD) simulation. The effects of solution pH and fluid impact angle on Al FAC were determined. An increase of solution pH enhances the activity of Al due to dissolution of Al oxide film in alkaline environment. Moreover, Al activity decreases with the increasing fluid impact angle to the specimen. A CFD simulation shows that, with the increase of impact angle, the electrode area under high-velocity flow field decreases and that under low-velocity flow field increases. Consequently, the shear str...

Energy Technology Data Exchange (ETDEWEB)

An experimental study of the hydrodynamics of a narrow channel was performed in order to obtain the heat transfer mechanisms and influences contributing to the flow regime transition from inverted annular to inverted slug flows for post dryout downflow. The experimental series consisted of both adiabatic and diabatic visualization tests over a wide range of fluid and thermal parameters. The system inlet gas velocities ranged from 0 to 14 meters per second while the inlet fluid velocities ranged from 1 to 3 meters per second. Full extent visualization of the flow regime was possible due to a quartz tube in tube construction with a clear heating fluid. Constant temperature heating of the freon was accomplished at bulk fluid temperatures above the critical heat flux temperature. For each hydrodynamic flow condition, one to ...

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A real-time neutron radiography (RTNR) system is used to determine two-phase flow parameters for a horizontal co-current two-phase flow channel with a cylindrical 37 rod bundle. Image processing techniques are applied to visualize the two-phase flow, and to determine flow regime, cross-sectional averaged void fraction, time averaged void fraction, and void distribution. The experimentally determined flow regime map disagrees with existing flow regime models developed for the cylindrical rod bundles. A new flow regime is observed and designated large amplitude stratified wavy (LASW) flow. The results show that the LASW flow regime may be due to a combination of undeveloped flow phenomena, boundary conditions, and circumferential cross flow occuring in the ...

International Nuclear Information System (INIS)

This paper describes two research programs which are currently underway in the author's laboratory to investigate the effect of fluid flow on the degradation of power plant materials in high temperature/high pressure aqueous environments. These programs include the design and operation of a controlled hydrodynamic corrosion testing apparatus that can be used to study the general and localized corrosion characteristics of alloys in simulated nuclear reactor environments, and a study of the effect of flow velocity on the stress corrosion cracking of ASTM A508 C1.2 steel and Type 304SS in simulated BWR heat transport fluids.

International Nuclear Information System (INIS)

Many pump reliability problems in the Nuclear Power Plants (NPPs) are being attributed to the operation of the pump at flow rates well below its best efficiency point(BEP). Generally, the manufacturer and the user try to avert such problems by specifying a minimum flow, below which the pump should not be operated. Pump minimum flow usually involves two considerations. The first consideration is normally termed the 'thermal minimum flow', which is that flow required to prevent the fluid inside the pump from reaching saturation conditions. The other consideration is often referred to as 'mechanical minimum flow', which is that flow required to prevent mechanical damage. However, the criteria for specifying such a minimum flow are not clearly understood by all parties concerned. Also various factor and ...

Energy Technology Data Exchange (ETDEWEB)

Moving out of the scientific community research laboratories, computational fluid dynamics (CFD) software packages are now allowing industrials to analyse and optimize industrial processes involving the use of gases, liquids and even some two-phase fluids. Their attractiveness and their impact stems out from the opportunity they offer to bring insight into an existing unit, or even at the design stage, by displaying the spatial distribution of process relevant variables such as temperature, concentration. The filling of the spacing in between a two-layer window is a simple example. This new opportunity of visualisation is at times an unique way, when the process environment is an opaque one, such as liquid metal flowing into a tundish or when measurements of flows may be a long and tedious work, such as flows within water treatment basins. This environment we are to investigate in ...

International Nuclear Information System (INIS)

Purpose: To secure the reactor operation safety by the provision of a fluid pressure detecting section for control rod driving fluid and a control rod interlock at the midway of the flow pass for supplying driving fluid to the control rod drives. Constitution: Between a driving line and a direction control valve are provided a pressure detecting portion, an alarm generating device, and a control rod inhibition interlock. The driving fluid from a driving fluid source is discharged by way of a pump and a manual valve into the reactor in which the control rods and reactor fuels are contained. In addition, when the direction control valve is switched and the control rods are inserted and extracted by the control rod drives, the pressure in the driving line is always detected by the pressure detection section, whereby if abnormal pressure is resulted, the alarm ...

British Library Electronic Table of Contents (United Kingdom)

In this article, the authors analyzed the effect of thermal conductivity on unsteady magnetohydrodynamic (MHD) free convection in a micro-polar fluid past a semi-infinite vertical porous plate. The fluid thermal conductivity is assumed to vary as a linear function of temperature. By using the Chebyshev collocation method in the spatial direction and the Crank-Nicolson method in the time direction, the boundary layer equations are transformed into a linear algebraic system. There are several material parameters whose affect on the flow have been studied, for instance, thermal conductivity, radiation, magnetic, micro-polar, suction (or injection) parameters, and Prandtl number. Boundary layer and Boussineq approximations have been introduced together to describe the flow field. The domain of...

International Nuclear Information System (INIS)

Flow-induced vibration is an important concern to the designers of heat exchangers subjected to high flows of gases or liquids. Two-phase cross-flow occurs in industrial heat exchangers, such as nuclear steam generators, condensers, and boilers, etc. Under certain flow regimes and fluid velocities, the fluid forces result in tube vibration and damage due to fretting and fatigue. Prediction of these forces requires an understanding of the flow regimes found in heat exchanger tube bundles. Excessive vibrations under normal operating conditions can lead to tube failure. Relatively little information exists on two-phase vibration. This is not surprising as single-phase flow induced vibration; a simpler topic is not yet fully understood. Vibration in two-phase is much more complex because it depends upon two-phase ...

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This paper describes the comprehensive modeling method of fluid and heat flows in the hydrological system. Based upon the concept that the hydrological system is composed of the air-water 2-phase fluids, and the rock phase, various natural processes are modeled including surface/subsurface 2-phase mass transfer, heat exchanges between fluid phases, between fluid and solid phases, and sensible/latent heat exchanges on the ground surface. A field-oriented numerical simulator is developed, in which a set of governing equations is solved for different variables on the surface and in subsurface regions, respectively. Results of an experimental study are presented, in which transient formulation of heat exchange between fluid/solid phases is examined through matching of the observation and calculated performances. (author)

International Nuclear Information System (INIS)

Computational fluid dynamics are applied to the study of three-dimensional fluid flow in a dense medium plasma reactor (DMPR) under different operating conditions. Reaction mechanisms and rates for the removal of methyl t-butyl ether (MTBE) in a DMPR are developed from experimental data to determine the plasma volume, the rate of interphase mass transfer and the photolysis rate of MTBE via UV emission from the plasma. The simulations utilize the plasma volume determined from the kinetic data to show that the volume of fluid in contact with the plasma in the DMPR only constitutes a maximum of approximately 10% of the fluid intended to be cycled through the plasma tubules. The simulations also predict appreciable pressure gradients on the surface of the pin electrodes, resulting in a small discharge area located away from the region in which the electric field strength is a maximum. ...

Energy Technology Data Exchange (ETDEWEB)

The flow distribution through a plate-fin heat exchanger is studied by using a computational fluid dynamics (CFD) code, FLUENT. The flow distribution through any heat exchanger affects its performance. In designing a heat exchanger, it is assumed that the fluid is uniformly distributed through the heat exchanger core. In practice, however, it is impossible to distribute fluid uniformly, because of an improper inlet configuration, imperfect design, and a complex heat transfer process. The CFD simulation of the flow distribution in the header of a conventional plate-fin heat exchanger is presented. It is found that the flow maldistribution is very serious in the y-direction of the header. A modified header is proposed and simulated using CFD. The modified header configuration has a more uniform flow distribution than the ...

UK PubMed Central (United Kingdom)

The computational fluid dynamics methods for the limited flow rate and the small dimensions of an intracranial artery stenosis may help demonstrate the stroke mechanism in intracranial atherosclerosis....Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Traditional two-phase flow-regime criteria based on the gas and liquid superficial velocities may not be suitable to the analyses of rapid transient or entrance flows by the two-fluid model. Under these conditions, it is postulated that direct geometrical parameters such as the void fraction are conceptually simpler and therefore more reliable parameters to be used in flow-regime criteria than the traditional parameters. From this point of view, new flow-regime criteria for upward gas-liquid flow in vertical tubes have been developed considering the mechanisms of flow-regime transitions. These new criteria can be compared to existing criteria and experimental data under steady-state and fully developed flow conditions by using relative velocity correlations. The criteria showed reasonable agreements with the existing ...

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A model of heterogeneous mechanism of nucleation on impurity particles in a fluid volume is proposed. The particle spectrum is reproduced by solving the ''inverse'' problems on stationary outflow of a boiling parahydrogen with the use of experimental data of authors. A relation for a closure of the equation system describing a non-equilibrium outflow is obtained. It is shown that within the investigated parameter range one manages to calculate the characteristics of a stationary outflow with a satisfactory accuracy.

Science.gov (United States)

We have analyzed the MHD flow of a conducting couple stress fluid in a slit channel with rhythmically contracting walls. In this analysis we are taking into account the induced magnetic field. Analytical expressions for the stream function, the magnetic force function, the axial pressure gradient, the axial induced magnetic field and the distribution of the current density across the channel are obtained using long wavelength approximation. The results for the pressure rise, the frictional force per wave length, the axial induced magnetic field and distribution of the current density across the channel have been computed numerically and the results were studied for various values of the physical parameters of interest, such as the couple stress parameter ?, the Hartmann number M, the magnetic Reynolds number R and the time averaged mean flow rate ?. Contour plots for the stream and magnetic force functions are obtained and ...

Science.gov (United States)

The results of a study conducted by Working Group 10 of the AGARD Fluid Dynamics Panel to investigate the limits of boundary layer methods, both the integral and field type formulations, for calculating three-dimensional turbulent separated flow are presented. Test cases used to assess the boundary layer calculations included the DFLVR prolate spheroid at angle of attack and the NASA-Ames Wing C. Comparisons between boundary layer calculations and experimental data are presented for these test cases along with observations, conclusions, and recommendations.

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The Porous media approach method was applied to the MULTID component of MARS which was developed by KAERI. This method has been widely used for analysis of large regions containing only fluid and for flows in regions with immersed solids. It can calculate flow distribution more correctly in case of flow area or volume change. Application of this method to the MULTID component in MARS was evaluated and the results were compared with those of CFD code, FLUENT. As a result, the calculated flow distributions of MARS and FLUENT show similar trend, so the effect of porous media in MARS can be applied to the other cases.

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The integrity of the RPV head and reactor internals was assessed by means of fluid-structural analyses using a coupled method to evaluate the water hammer phenomenon arising from high burnup fuel failure under RIA conditions. The fluid viscosity effect on the water column burst as well as the complex three-dimensional flow paths caused by a core shroud and standpipes were considered in this study. The three analysis scenarios were designed to investigate the above mentioned influential factors separately. In the first scenario, a two-dimensional axisymmetric reactor vessel model without any reactor internals was modeled to assess the influence of the fluid dynamics in the NSC RIA regulatory evaluation. This model has an actual RPV geometry and can be simply separated from other influential factors in order to concentrate only on investigation of the fluid viscosity effect. In the ...

Energy Technology Data Exchange (ETDEWEB)

Condensing two-phase channel flow occurs in many industrial applications, including heating and refrigeration systems. It can also occur in certain nuclear reactor accidents. For example, during a small-break loss-of-coolant accident in a pressurized water reactor, following the partial depletion of the primary coolant, condensation of steam on the primary side of the steam generator tubes can provide a heat sink for disposal of the decay heat generated in the reactor core. Condensing two-phase flow can also play an important role in the operation of the passive emergency cooling system in the advanced simplified boiling water reactor. Here, steady-state condensation in the presence of a noncondensable in a concurrent two-phase channel flow is analyzed using a two-fluid model. The effect of noncondensables on the combined heat transfer at the liquid-gas mixture interphase is accounted for by using the ...

British Library Electronic Table of Contents (United Kingdom)

A non-similar boundary layer analysis is presented to study the flow, heat and mass transfer characteristics of non-Darcian mixed convection of a non-Newtonian fluid from a vertical isothermal plate embedded in a homogeneous porous medium with the effect of Soret and Dufour and in the presence of either surface injection or suction. The value of the mixed-convection parameter lies between 0 and 1. In addition, the power-law model is used for non-Newtonian fluids with exponent n1 for dilatant fluids. Furthermore, the coordinates and dependent variables are transformed to yield computationally efficient numerical solutions that are valid over the entire range of mixed convection, from the pure forced-convection limit to the pure free-conve...

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A quantitative description is proposed for the depletion-induced slip thickness and velocity profile of a polymer solution near the wall-fluid interface in simple shear flow. The inhomogeneous polymer density profile at a flat wall is inserted into the equations of motion for the flow of a polymer solution near the flat wall. The theory is in quantitative agreement with simulation results. (letter to the editor)

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A continuous-flow filter/concentrator for separating and/or concentrating particles in a fluid is disclosed. The filter is a three-port device an inlet port, an filter port and a concentrate port. The filter separates particles into two streams by the ratio of their dielectrophoretic mobility to their electrokinetic, advective, or diffusive mobility if the dominant transport mechanism is electrokinesis, advection, or diffusion, respectively.Also disclosed is a device for separating and/or concentrating particles by dielectrophoretic trapping of the particles.

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The scale-down of a liquid mini-pump (order of 10 mm) to a micrometre scale has been attempted using a novel valveless nozzle-diffuser design and new application of an organic physical vapor-deposited membrane. The micropump employs no moving parts other than the membrane and accomplishes the rectification of fluid flow due to pressure recovery differences in the nozzle and diffuser flow directions. More specifically, liquids flow with less resistance (i.e. conduct more fluid) in the diffuser direction than the nozzle direction, for a given pressure differential. At the micrometre scale, the fabrication of the critical nozzle and diffuser elements was performed by focused ion beam (FIB) microlithography of glass slides. Etched slides were sandwiched to make two-dimensional venturis. Sternme and Sternme noted the importance of a lower Reynolds Number linfit on the desired pressure ...

International Nuclear Information System (INIS)

To develop the advanced subchannel analysis code, the dominant factors that influence the boiling transitional process must be taken into account in the mechanistic constitutive equations based on the flow geometries and the fluid properties. The dominant factors that influence the boiling transitional processes are (1) the gas-liquid re-distribution by cross flow, (2) the liquid film dryout, (3) the two-phase flow regime transition, (4) the droplet deposition, and (5) the spacer-droplet interaction. At first, we indicated the strategy for the development of the constitutive equations for the five dominant factors based on the experimental database by the latest measurement technique and the latest computational fluid dynamics method. Then, the problems of the present constitutive equations and the improvement plan of the constitutive equations were indicated. Finally, the layered ...

International Nuclear Information System (INIS)

Three dimensional temperature field and helium flow field of TBM are simulated using the general purpose computational fluid dynamics (CFD) code FLUENT. The temperature distribution of Be Armor, Be Pebble Bed, Li_4SiO_4 Pebble Bed, Structure Material of TBM, and helium flow field in the cooling pipe are presented. The research indicates that the work temperature of each material is under the material temperature allowed except some places where high temperature should be excluded in the design. The results will provide references for further optimized thermal hydraulic design of ITER China TBM. (authors)

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This investigation concerns the nonlinear dynamics of heat transfer from a surface using an upstream eddy promoter. A numerical model is developed for the coupled fluid flow and heat transfer process based on a modified MacCormack scheme. Numerical simulations are carried out to determine the response and heat transfer enhancement due to the promoter. The average heat transfer from a cavity floor is seen to be increased by a factor of approximately five over the unpromoted'' flow. Another interesting feature of the study is the nonlinear viscous flow dynamics from the cylinder-wall interaction which differ significantly from the familiar cylinder-free stream patterns.

Science.gov (United States)

It is shown that the method used for comparing theoretical and experimental results is erroneous and the values of the couple stress parameters obtained for blood flow are incorrect. A method for determining the couple stress parameters is presented. The computational work in the improved method is considerably less. It is observed that both the couple stress parameters are functions of concentration. An empirical relation between concentration and the stress parameters is obtained. The shear viscosity and non-dimensional axial velocity are functions of concentration. Some uses of determining the values of the couple stress parameters are suggested.

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Sudden changes in the temperature of flowing liquids can result in transient buoyancy forces which strongly impact the flow hydrodynamics via flow stratification. These effects have been studied for the case of potential flow of stratified liquids to line sinks, but not for moderator flow in SRS reactors. Standard codes, such as TRAC and COMMIX, do not have the capability to capture the stratification effect, due to strong numerical diffusion which smears away the hot/cold fluid interface. A related problem with standard codes is the inability to track plumes injected into the liquid flow, again due to numerical diffusion. The combined effects of buoyant stratification and plume dispersion have been identified as being important in operation the Supplementary Safety System which injects neutron-poison ink into SRS reactors to provide safe ...

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The Computational Fluid Dynamics(CFD) study was conducted to assess the new design concept introduced to solve the issues on the flow deviation between SG cassettes and the supporting structure design of the flow distributing plate subjected to the flow induced vibration. Flow field from MCP to the bottom of SG was modeled for 2-dimensional(2D) CFD analysis and then sensitivity analysis on major design parameters was conducted using commercial CFD code, Fluent. The cases for detailed 3D analysis were selected based on the result of 2D analysis and the detailed 3-dimensional(3D) analysis was conducted for these selected cases using Fluent code. Flow field was modeled by RNG model and wall function, 2nd upwind scheme, porous model, structured or hybrid grid. The analysis result shows that the maximum deviation of flow distribution between SG ...

International Nuclear Information System (INIS)

Full text of publication follows: As the coolant experiences no phase change in the core, SCWRs, unlike LWRs, cannot use design criteria based on the critical heat flux concept. The commonly accepted practice in SCWRs is to specify cladding temperature limits that must be met during transient and accident events. Therefore for the design of the SCWR, it is very important to predict the heat transfer coefficient to the supercritical water coolant with great accuracy. Our recent study focuses on the critical issue of measuring heat transfer to supercritical water at prototypical SCWR conditions and to develop the tools to predict the SCWR thermal behavior. A heat transfer test loop using a surrogate fluids, CO_2, is under construction. The reason of using CO_2 instead of water is that (i) valuable insight of the physical phenomena can be obtained with this fluid, and (ii) some existing facilities already used surrogate ...

Energy Technology Data Exchange (ETDEWEB)

The core bypass flow in a prismatic very high temperature gas-cooled reactor (VHTR) is one of the important design considerations which impacts considerably on the integrity of reactor core internals including operating fuels. The interstitial gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The occurrence of hot spots in the core and lower plenum and hot streaking in the lower plenum (regions of very hot gas flow) will be affected by the bypass flow. In the present study, three-dimensional computational fluid dynamic (CFD) calculations of a typical prismatic VHTR are conducted to understand better the bypass flow phenomenon and establish the ...

Science.gov (United States)

Flow structures and heat transfer at the liquid-liquid interface are investigated experimentally and analytically in the entrance region of a liquid metal-water stratified flow in a horizontal rectangular channel. The two-equation model and the mixing length mode, including a damping turbulent region near the interface, are used to obtain analytical results for pressure drop, position of the interface, and heat transmission coefficients across the interface. Analytical results are compared with experimental results. Conclusions are presented and include the following: (1) vertical position of the interface increases or decreases along the stream according to the fluid flow rate of both fluids, and then approaches a constant value in the fully developed region; (2) pressure drop increases along the stream from the minimum value at the inlet; and (3) heat transmission coefficients ...

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A new double-null, slotted divertor configuration will be installed for the DIII-D Radiative Divertor Program at General Atomics in late 1996. Four cryocondensation pumps, three new and one existing, will be part of this new divertor. The purpose of the pumps is to provide plasma density control and to limit the impurities entering the plasma core by providing pumping at each divertor strike point. The three new pumps are based on the design of the existing pump, installed in 1992 as part of the Advanced Divertor Program. The new pumps require geometry modifications to the original design. Therefore, extensive modal and dynamic analyses were performed to determine the behavior of these pumps and their helium and nitrogen feed lines during disruption events. Thermal and fluid analyses were also performed to characterize the helium two-phase flow regime in the pumps and their feedlines. A flow testing program was completed to ...

Energy Technology Data Exchange (ETDEWEB)

The present paper investigates the peristaltic transport of a couple stress fluid in an asymmetric channel with the effect of the induced magnetic field. The exact solutions of momentum and the magnetic field equations have been calculated under the assumptions of long wave length and low but finite Reynolds number. The expression for pressure rise has been computed numerically using mathematics software Mathematica. The graphical results have been presented to discuss the physical behavior of various physical parameters of interest. Finally, the trapping phenomena have been discussed for various physical parameters. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Westinghouse Electric Germany GmbH has developed fluid dynamic models for medium-actuated armatures using the thermal hydraulic code RELAP5 in order to reach a more realistic description of the armature behavior including fluid-structure interactions in case of transient flow conditions in piping systems. The contribution is concerned with the modeling of damped check valves. The model allows the description of the behavior during opening and closure of a check armature. The calculated results show good agreement with the available measured data.

Science.gov (United States)

Radon-222 was shown to be useful in-situ tracer for studying thermodynamic, geologic, and transport properties of geothermal reservoirs. The relationships to reservoir properties are based on steady-state and non-steady-state models which incorporate the thermodynamic state and relative mobility of the fluids, and partitioning between the fluid phases. The steady-state thermodynamic models assume equilibrium between radon emanation from the reservoir rock and the geofluid concentration. The non-steady-state model solves the partial differential equations describing radon transport under transient two-phase geothermal flow conditions. Radon concentrations of fluids from nine geothermal reservoirs showed strong correlations to the specific volume of the reservoir fluid. Lowest values were associated with all-liquid wells at Cerro Prieto, Wairakei, and Los Azufres reservoirs, and the ...

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A system and method for installing a fluid flow controller and telescoping spools beneath an offshore bottom supported drilling rig rotary table is disclosed. Upper and lower telescoping spools are provided for initially connecting a Diverter/BOP convertible fluid flow controller between structural casing in the well and a permanent housing beneath the drilling rig rotary table. Clamp means are provided for clamping the rig vent line to an opening in the housing wall of the fluid flow controller during drilling of the borehole through the structural casing in preparation for setting and cementing the conductor casing. In that mode, the system is adapted as a diverter system. After the well is drilled for the conductor casing and the conductor casing is cemented and cut off at its top, a mandrel is fitted at the top of the conductor casing to which the lower end ...

International Nuclear Information System (INIS)

Youngkwang Unit 3,4 and Ulchin Unit 3 and 4 have had problem of the KSNP Steam Generator due to a severe fretting wear on the tube. In particular, the wears were localized and concentrated in the upper part of U-bend of the Central Cavity region. At the upper tube bundle Central Cavity, the fluid flow velocities and void fraction are very high, because the steam is made by high heat transfer at secondary region. Also, this region is affected easily by fretting wear due to it's unsupported span is longer than another regions. The fretting wear is assumed to be result of Flow-Induced Vibration (F. I. V), which can occur by many mechanisms. EFDP was added to UCN 5,6 for prevent fretting wear by the SEC LCC and DSHIC, a company of design and manufacture of the steam generator, respectively. In order to evaluate the efficacy of EFDP, ANSYS and ATHOS-3 Code were used. From sensitivity analysis and calculation results, Density and ...

Energy Technology Data Exchange (ETDEWEB)

An ion processing element employing composite media disposed in a porous substrate, for facilitating removal of selected chemical species from a fluid stream. The ion processing element includes a porous fibrous glass substrate impregnated by composite media having one or more active components supported by a matrix material of polyacrylonitrile. The active components are effective in removing, by various mechanisms, one or more constituents from a fluid stream passing through the ion processing element. Due to the porosity and large surface area of both the composite medium and the substrate in which it is disposed, a high degree of contact is achieved between the active component and the fluid stream being processed. Further, the porosity of the matrix material and the substrate facilitates use of the ion processing element in high volume applications where it is desired to effectively process a high volume ...

International Nuclear Information System (INIS)

We review the current status of Andreev reflection spectroscopy on the heavy fermions, mostly focusing on the case of CeCoIn5, a heavy-fermion superconductor with a critical temperature of 2.3 K. This is a well-established technique to investigate superconducting order parameters via measurements of the differential conductance from nanoscale metallic junctions. Andreev reflection is clearly observed in CeCoIn5 as in other heavy-fermion superconductors. Considering the large mismatch in Fermi velocities, this observation seemingly appears to disagree with the Blonder-Tinkham-Klapwijk (BTK) theory. The measured Andreev signal is highly reduced to the order of maximum ?13% compared to the theoretically predicted value (100%). The background conductance exhibits a systematic evolution in its asymmetry over a wide temperature range from above the heavy-fermion coherence temperature down to well below the superconducting transition temperature. Analysis of the ...

Energy Technology Data Exchange (ETDEWEB)

Real-time neutron radiography (RTNR) is now proving to be a valuable research tool in the study of hydrogenous fluid flow. One of the most significant advantages of neutron radiography is the ability to image hydrogenous substances (such as lubricants, coolants, and fuels) inside metallic materials such as aluminum and titanium engines. By using RTNR, one can then study dynamic events such as the movement of liquids inside these solids. The Phoenix Memorial Laboratory (PML) at the University of Michigan has recently developed and installed a facility dedicated to RTNR. The work at PML has shown that RTNR of dynamic events can provide information enabling the researcher to follow dynamic events that were previously impossible or impractical. This paper will show the variety of uses of RTNR presently being pursued at PML.

International Nuclear Information System (INIS)

Designs of nuclear reactor plants aim for high performance under safety consideration. Because of large scale and high pressure/temperature conditions, data from costly mockup tests have been required to verify simulation codes of systems and components. Establishment of design by analysis (DBA) in nuclear engineering is required for development of next generation nuclear reactors. Recent powerful computers and simulation technique enable numerical analyses to predict realistic behaviors of thermo-fluid flow, structure and do on. The present report describes resent simulation results of complex gas-liquid two-phase flow, large scale structure dynamics and fluid-structure interaction. (author)

International Nuclear Information System (INIS)

A program under the sponsorship of the United States Nuclear Regulatory Commission was intiated at the Oak Ridge National Laboratory (ORNL) in late 1977. The program, Advanced Instrumentation for Reflood Studies (AIRS), is charged with developing instrumentation for measurement of in-vessel fluid phenomena in pressurized water reactor reflood facilities. The goal of the ORNL program is to develop techniques and systems for measuring fluid flow in-core, deentrainment in the upper plenum and liquid fallback from the upper plenum into the core. A large portion of the development at ORNL is devoted to the impedance probes for measurement of two-phase flow velocities and void fractions. Film probe development at ORNL is limited to adapting the present techniques to the environment of a reflood facility. As the development progresses on all the measurement techniques, ORNL will fabricate and supply instrument ...

Energy Technology Data Exchange (ETDEWEB)

A numerical analysis is performed to clarify the heat transfer characteristics of combined convection around the tubes which form a single row perpendicularly arranged to a forced flow in the direction of gravity. A boundary-fitted coordinate transformation technique is adopted to solve the governing equations numerically. It is found in the case of liquid sodium that gravity-induced flow gives no substantial effect to heat transfer augmentation in a low Reynolds number region while it can be sufficiently expected in the ordinary fluids in the same Reynolds number region. This means that such heat transfer augmentation as expected in ordinary fluids can not be realized when crossflow-type heat exchangers installed for decay-heat removal operates in a low Reynolds number region.

Energy Technology Data Exchange (ETDEWEB)

For the application of dynamic neutron radiography to the two-phase flow research using HANARO, several experimental items to which the radiography technique is beneficial were identified through the review of the outputs from the related researches and the discussions with experts. Also, the investigation of the equipments including the beam port, camera and converter was made and a hardware and a software for image processing were equipped. It was confirmed that the calibration curve for the attenuation of neutron beam in fluid which is required for the two-phase flow experiment could be obtained by the computer code calculation. Based on the investigation results on the equipment and the results from the measurement of BNCT beam characteristics, a high speed camera and an image intensifier will be purchased. Then, the high speed dynamic neutron radiography facility for two-phase flow experiments will ...

International Nuclear Information System (INIS)

Visualization of a liquid metal flow and image processing methods to measure the vector field are carried out by real-time neutron radiography. The JRR-3M real-time thermal neutron radiography facility in the Japan Atomic Energy Research Institute was used. Lead-bismuth eutectic was used as a working fluid. Particles made from a gold-cadmium intermetallic compound (AuCd_3) were used as the tracer for the visualization. The flow vector field was obtained by image processing methods. It was shown that the liquid metal flow vector field was obtainable by real-time neutron radiography when the attenuation of neutron rays due to the liquid metal was less than l/e and the particle size of the tracer was larger than one image element size digitized for the image processing. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The use of capacitance sensors for measuring phase concentrations in two-phase flow has gained popularity in recent years. In designing such sensors, there are many issues which must be considered in order to optimize performance: two-phase flow regime, permittivity of the phases, duct geometry, electrical shielding, desired spacial resolution of film thickness, and temperature variation in the flow field. These design issues are discussed and are used to optimize the design of a capacitance sensor which is used to measure vapor volume fraction in annular, two-phase vertical upflow and downflow in a square duct. The sensor was tested and implemented in a 12.7 mm square duct mounted in a flow boiling facility containing FC-72, a low permittivity dielectric fluid ({epsilon}{sub r} = 1.75). Using analytical modeling, an adjustable-length, parallel-plate design was developed and refined ...

Energy Technology Data Exchange (ETDEWEB)

Two-phase pressure drop and fluctuating static pressures were measured in a small horizontal rectangular channel (hydraulic diameter = 5.44 mm). The two-phase fluid was an air/water mixture at atmospheric pressure tested over a mass flux range of 50 to 2,000 kg/m[sup 2] [center dot] s. Two-phase flow patterns were identified and an objective method was found for determining the flow pattern transition from bubble or plug flow to slug flow. The method is based on an RMS static pressure measurement. In particular, it is shown that the transition is accompanied by a clear and abrupt increase in the RMS pressure when plotted as a function of mass quality. Use of the RMS pressure as a two-phase flow pattern transition indicator is shown to have advantages over pressure-versus-time trace evaluations reported in the literature. The transition is substantiated by a ...

International Nuclear Information System (INIS)

Entropy generation is equivalent to destruction of available work (exergy). The useful energy is destroyed due to the intrinsic irreversibility associated within thermodynamic systems. Exergy analysis can be used as an effective basis for the development and improvement of systems design not only in the overall perspective but also in the individual component level. Second law analysis provides a useful tool to identify the irreversibility in any thermal system. This study presents the investigation of local and total entropy generation in compressible flow through a diffuser. Air is used as the fluid. Uniform heat flux boundary condition is applied at the wall. Two dimensional solution of velocity and temperature fields are obtained using the CFD code FLUENT. Distribution of entropy generation rate is investigated throughout the volume of the fluid as it flows through the diffuser. Regions of high ...

International Nuclear Information System (INIS)

A vortex diode has been developed as a reverse flow limiter in the primary circuit of an advanced gas cooled reactor. In addition to the development work on a prototype diode to optimise performance and geometry, measurements were also made on an available experimental diode of similar size with pressure differences up to 4 MPa and temperatures up to 600 K using nitrogen, argon and carbon dioxide as the test fluids. Correlation of data from all tests was satisfactorily obtained using isentropic one-dimensional nozzle flow equations. (author).

Energy Technology Data Exchange (ETDEWEB)

Severe pitting corrosion occurred in a horizontal steel pipeline used to transport multiphase fluid, including water, oil, and natural gas, after 2 months of service. The pitting corrosion rate was up to 42 mm/year. Chemical analysis, X-ray diffractometry, and EDAX showed that the corrosion products mainly consisted of Fe9S8, FeCO3, and NaCl. Calcium containing inclusions were also found in the matrix of the steel, which may accelerate corrosion. The early failure was attributed to the high proportion of water, the slow flow velocity, and the use of unqualified material. (Author)

Energy Technology Data Exchange (ETDEWEB)

Contents include: countermeasures to save energy of sintering plant and future plans in fukuyama works; improvement of surface quality of continuous-casting slab; development of direct quenching and tempering type HT80 steel with good weldability; numerical analysis of fluid flow in a geothermal reservoir; the finite-element calculation of turbulent flow using the universal law of the wall; development of PC 4 dual fuel engine; design of industrialized housing; Computer-aided Navigation system (CANSY); and new production control system in Fukuyama Works.

British Library Electronic Table of Contents (United Kingdom)

The present contribution deals with the thermophoresis particle deposition and thermal radiation effects on the flow, heat and mass transfer characteristics in a viscous fluid over a semi-infinite vertical porous plate. The governing boundary layer equations are written into a dimensionless form by similarity transformations. The transformed coupled nonlinear ordinary differential equations are solved numerically by means of the fourth-order Runge?Kutta method with a shooting technique. The effects of different parameters on the dimensionless velocity, temperature, and concentration profiles are shown graphically. In addition, results for the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are tabulated and discussed.

International Nuclear Information System (INIS)

The operation and safety of both fossil-fuel and nuclear power stations depend on adequate cooling of the thermal source involved. This is usually accomplished using liquid coolants that are forced through the high temperature regions by a pumping system; this fluid then transports the thermal energy to another section of the power station. However, fluids that undergo boiling during this process create vapor that can be detrimental, and influence safe operation of other system components. The behavior of this vapor, or void, as it is generated and transported through the system is critical in predicting the operational and safety performance. This study uses two advanced penetrating radiation techniques, Real Time Neutron Radiography (RTNR), and High Speed X-Ray Tomography (HS-XCT), to examine void generation and transport behavior in a flow boiling system. The geometries studied were tube side flow ...

Energy Technology Data Exchange (ETDEWEB)

A numerical study has been performed to investigate the hydrodynamic aspects of the pool boiling on horizontal-, vertical- and downward-facing surfaces. The FlowLab code, which is based on a Lattice-Boltzmann (LB) model of two-phase flows, is employed. Macroscopic properties, such as surface tension ({sigma}) and contact angle ({beta}), are implemented through the fluid-fluid (G{sub {sigma}}) and fluid-solid (G{sub t}) interaction potentials. The model is found to express a linear relation between the macroscopic properties ({sigma}, {beta}) and microscopic parameters (G{sub {sigma}}, G{sub t}). The simulation results on bubble departure diameter appear to have the same parametric dependence as the empirical correlation. Hydrodynamic aspects of two-phase flow regime transition mechanism are investigated for different surface-coolant configurations. Results of the LB simulation ...

Energy Technology Data Exchange (ETDEWEB)

The fluid-induced vibration level of instrumented capsule, which was manufactured for fuel irradiation test at the reactor core of HANARO, was investigated. For this purpose, the instrumented capsule was loaded at the OR site of the HANARO design verification test facility that could simulate identical flow condition as the HANARO core. Then, vibration signals of the instrumented capsule subjected to various flow conditions were measured by using vibration sensors. In time domain analysis, maximum amplitudes and RMS values of the measured acceleration and displacement signals were obtained. By using frequency domain analysis, frequency components of the fluid-induced vibration were analyzed. In addition, natural frequencies of the instrumented capsule were obtained by performing modal test. The frequency analysis results showed that the natural frequency components near 7.5Hz and 17.5Hz were dominant in ...

Energy Technology Data Exchange (ETDEWEB)

This study presents a dynamic analysis of a rotor supported by two turbulent flow model journal bearings and lubricated with couple stress fluid under nonlinear suspension. The dynamics of the rotor center and bearing center is studied. The dynamic equations are solved using the Runge-Kutta method. The analysis methods employed in this study is inclusive of the dynamic trajectories of the rotor center and bearing center, power spectra, Poincare maps and bifurcation diagrams. The maximum Lyapunov exponent analysis is also used to identify the onset of chaotic motion. The results show that the values of dimensionless parameters l* strongly influence dynamic motions of bearing and rotor centre. It is found that couple stress fluid improve the stability of the system when l* > 0.4 even if the flow of this system is turbulent. We also demonstrated that the dimensionless rotational speed ratios s and ...

Energy Technology Data Exchange (ETDEWEB)

Ejector refrigeration systems are usually designed to utilize low grade energy for driving the cycle. They also have low maintenance cost because they operate without a compressor. Mainly, the ejector performance directly affects the refrigerating performance. Therefore, an investigation on the characteristics and an efficient design of the ejector are important to improve ejector refrigeration systems. In this study, the computational fluid dynamics (CFD) code, FLUENT, is employed to predict the flow phenomena and performance of CPM and CMA steam ejectors. The ejector refrigeration system, using water as the working fluid, is operated at 120-140 C boiler temperature and 5-15 C evaporator temperature. CFD can predict ejector performance very well and reveal the effect of operating conditions on an effective area that is directly related to its performance. Besides, it is found that the flow pattern does ...

Energy Technology Data Exchange (ETDEWEB)

Full text of publication follows:In order to practice a design-by-analysis of thermohydraulics design of BWR fuel rod bundles, the subchannel analysis would play a major role. There, the immediate concern is improvement in its predictive capability of CHF due in particular to the film dryout (boiling transition phenomena: BT) on the fuel rod surface. Constitutive equations in the subchannel analysis formulation are responsible for the quality of calculated results. The constitutive equations are a result of integration of the local and instantaneous description of two-phase flows over the subchannel control volume. In general, they are expressed in terms of subchannel-control-volume- as well as area-averaged two-phase flow state variables. In principle the information on local and instantaneous physical phenomena taking place inside subchannels must be counted for in the algebraic form of the equations on the basis of a more mechanistic ...

DEFF Research Database (Denmark)

Stereoscopic Particle Image Velocimetry (PIV) measurements are made in horizontal planes in a simplified scale model of a spray dryer using water as fluid. The sample rate was sufficient to resolve phenomena at lower frequencies. Data reveal asymmetric velocity fields in both mean fields and dynamics. Data were analysed using Proper Orthogonal Decomposition (POD). An important periodic event is an elongation of the jet core cross section that results in a downstream displacement of the jet towards the chamber wall.

International Nuclear Information System (INIS)

We exploit theoretically a class of rectangular cylindrical devices for noise shielding by using acoustic metamaterials. The function of noise shielding is justified by both the far-field and near-field full-wave simulations based on the finite element method. The enlargement of equivalent acoustic scattering cross sections is revealed to be the physical mechanism for this function. This work makes it possible to design a window with both noise shielding and air flow. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Energy Technology Data Exchange (ETDEWEB)

Four subprojects were completed: development and evaluation of die coatings, accelerated die life characterization of die materials, evaluation of fluid flow and solidification modeling programs, selection and characterization of Al-based die casting alloys, and influence of die materials and coatings on die casting quality.

Energy Technology Data Exchange (ETDEWEB)

The explosive known under the name Saletrol (mixture of ammonium nitrate and hydrocarbon fuel or a mixture of ammonium nitrate, hydrocarbon fuel and aluminum powder) is characterized by the absence of physical stability during storage (the oily fluid flows from the upper layers of the explosive downward) and as a consequence of this, decrease in the required effectiveness of blasting and increased release of toxic gaseous blasting products. In order to eliminate this shortcoming, lightening clay is added to Saletrol in a quantity of 3-12% by weight of the total explosive mass.

Energy Technology Data Exchange (ETDEWEB)

The enhancement of longitudinal heat transfer by means of fluid pulsation in a pipe has been investigated analytically and numerically, including the transient state. The effects of pulsation amplitude, frequency, and pipe length on thermal properties such as effective thermal diffusivity and delay time are clarified. Their effects on numerical calculations are also presented and suggestions for efficient numerical calculations of this problem are made concerning the combination of parameters.

Energy Technology Data Exchange (ETDEWEB)

The 3-D model program was developed to apply a mise-a-la-masse method to linear current sources with optional shapes. Mise-a-la-masse method is a bipolar mapping survey method using current sources installed in wells, and recently has been widely used for direct exploration of geothermal reservoirs. This method is also used for monitoring underground fluid as electrode arrangement of fluid flow tomography for surveying underground fluid (geothermal fluid, underground water, petroleum). In the geothermal reservoir exploration, the casing pipes of wells are used as linear current sources, and measured data are processed as those based on vertical current source. In the largely inclined well, the inclination of current sources should be considered. The 3-D modeling program was developed by difference calculus using the theoretical potential equation and apparent resistivity based on ...

International Nuclear Information System (INIS)

A commercial CFD code, Fluent, has been used to analyse the design of a filter-press reactor operating with characteristic linear flow velocities between 0.024 and 0.192 m s-1. Electrolyte flow through the reactor channel was numerically calculated using a finite volume approach to solve the Navier-Stokes equations. The length of the channel was divided into 7 sections corresponding to distances of 0, 0.01, 0.04, 0.08, 0.12, 0.14 and 0.15 m from the electrode edge nearest to the inlet. The depth of the channel was divided into three planes parallel to the channel bottom. For each channel section, a velocity profile was obtained at each depth together with the average velocity in each plane. The flow predictions show that the flow development, as the electrolyte passes through the cell, is strongly affected by the manifold causing strong vortex structures at the entrance and exit of the channel. Although ...

International Nuclear Information System (INIS)

This specialist meeting on Advanced Instrumentation and Measurements Techniques was held in Santa Barbara (USA) in 1997 and attracted some 70 participants in ten technical sessions and a session of the round table discussions, with a total of 41 papers. It was intended to bring together the international experts in multi-phase flow instrumentation, experiment and modeling to review the state-of-the-art of the two-phase flow instrumentation methods and to discuss the relation between modeling needs and instrumentation capabilities. The following topics were included: Modeling needs and future direction for improved constitutive relations, interfacial area transport equation, and multi-dimensional two-fluid model formulation; local instrumentation developments for void fraction, interfacial area, phase velocities, turbulence, entrainment, particle size, thermal non-equilibrium, shear stress, nucleation, condensation and ...

International Nuclear Information System (INIS)

Scaling criteria for a natural-circulation loop are examined. The present state of knowledge of scaling to obtain similarity during single- and two-phase flow conditions in a closed loop are reviewed, and an alternative development of two-phase similarity parameters is presented. The loop scaling criteria are the results of analyses in which flow from one component to another is considered. In this work, boundary conditions for the closed loop are developed to obtain scaling criteria for leak flow, injection flow, and heat loss to ambient. The leak scaling criteria are specialized for modeling approaches using prototypic fluid at prototypic or reduced pressures. The derived scaling parameters are examined for their application to two existing scaled test facilities: the Multi-Loop Integral System Test (MIST) facility at Babcock and Wilcox, and the UMCP 2 x 4 facility at the ...

Energy Technology Data Exchange (ETDEWEB)

The propagation of acoustic pressure perturbations in an adiabatic low-quality air/water flow were investigated both theoretically and experimentally. A linearized dispersion model is correlated with data to extract information on the behavior of interfacial momentum transfer controlled by the virtual volume coefficient. The dispersion model is examined in limiting cases of low and high frequency and related to current models for critical flow velocity. Fourier decomposition techniques are employed to predict the dispersion of measured pressure pulses and to relate data for standing waves and propagating pulses. The dispersion model is based on a two-fluid model and is the most complete model available in the literature at this time. The dispersion data presented herein is also the best available to date for low frequency (i.e., frequencies less than bubble resonance) sound propagation in bubbly air/water mixtures.

Energy Technology Data Exchange (ETDEWEB)

The energy available from tidal currents is substantial and considerable work has been conducted into determining the size of the resource and what the large-scale consequences of extraction might be. This paper describes the work conducted to establish a laboratory-scale model, by using the commercial computational fluid dynamics (CFD) code FLUENT trademark, in order to predict local-flow consequences resulting from the extraction of energy in two and three dimensions from within the water column in a tidal flow. As might be expected, a wake is formed but there is considerable localized flow acceleration around and, most especially, under an extraction zone. The wake behind the device is shown to be associated with a drop in the free surface which, in turn, is associated with the decline in the wake itself. (author)

British Library Electronic Table of Contents (United Kingdom)

The current paper continues the analysis of a completely novel method of fluid manipulation technology in micro-fluidics systems, inspired by nature, namely by the mechanisms found in ciliates. More information on this subject can be found at http://www.hitech-projects.com/euprojects/artic/. In order to simulate the drag forces acting on an array of artificial cilia, we have developed a computer code that is based on fundamental solutions of Stokes flow in a semi-infinite domain. The actuation mechanism consists of a bi-directional rotating excitation magnetic field. The magnetization induced by the magnetic field was calculated in a separate routine based on the Integral Nonlinear Equations Approach with 1D discretization of wire (cilium). Time averaged x-coordinate mass flow rates, strea...

Energy Technology Data Exchange (ETDEWEB)

This paper reports that fluidelastic instability is the most important vibration excitation mechanism for heat exchanger tube bundles subjected to cross-flow. Most of the available data on this topic have been reviewed from the perspective of the designer. Uniform definitions of critical flow velocity for instability, damping, natural frequency and hydrodynamic mass were used. Nearly 300 data points were assembled. The authors found that only data from experiments where all tubes are free to vibrate are valid form a design point of view. In liquids, fluid damping is important and should be considered in the formulation of fluidelastic instability. From a practical design point of view, we conclude that fluidelastic instability may be expressed simply in term of dimensionless flow velocity and dimensionless mass-damping. There is no advantage in considering more sophisticated models at this time. ...

International Nuclear Information System (INIS)

Recent experimental and theoretical studies of two-dimensional (2D) turbulence reveal that spectrally condensed turbulence which is a system of coupled large-scale coherent flow and broadband turbulence, is similar to plasma turbulence near the L-H transition threshold. Large condensate vortices fed via the turbulent inverse energy cascade, can control both the level of the broadband turbulence by shear decorrelation, and the energy injected into turbulence at the forcing scale via sweeping of the forcing-scale vortices. The interaction between these ingredients of spectrally condensed fluid turbulence is in many aspects similar to the interactions in the zonal flow-GAMs-turbulence system in plasma. In this paper we overview recent results on condensed 2D turbulence and present evidence of interaction between its three components: condensate structures, turbulence and forcing-scale vortices. This is compared with the ...

Energy Technology Data Exchange (ETDEWEB)

This report describes in detail the First Generation Duct Injection Model developed for the analysis of the fundamental processes of flue gas desulfurization by sorbent injection. The model is a two- and three-dimensional, multiphase reacting flow analyzer using computational fluid dynamics methods. The gaseous phase is solved in an Eulerian frame while the droplets or particles are tracked in a Lagrangian frame. The model has an associated preprocessor which allow easy problem set up by the use without in-depth knowledge of computational fluid dynamics. The aerodynamics of the First Generation Duct Injection Model have been successfully validated with a number of test cases for which experimental data are available. Data from the Meredosia pilot plant humidification tests have been used to validate the gas and droplet dynamics of the model with good agreement. Comparison of SO{sub 2} removal results using the present model ...

International Nuclear Information System (INIS)

Fluid dynamic analysis of a commercial, counter-flow Ranque-Hilsch Vortex Tube (Rh vt), Ex air 25 s cfm, has been performed in this work both experimentally and numerically; in particular Rh vt cooling power and temperature separation performances have been tested in both direct cooling employment (jet impingement) and indirect cooling employment (supplying cold plates). Experimental techniques, used in this work, revealed several difficulties to produce detailed information about velocity and temperature fields inside the tube and at both the exits. Hence numerical simulation of the flow inside the tube has been conducted using the commercial Cfd code Fluent 6.3.26. Compressible, turbulent, high swirling flow inside Rh vt has been simulated by using both Rans and Les approaches. In particular several turbulence closures have been used in the Rans simulations and results have been compared with Les ...

Energy Technology Data Exchange (ETDEWEB)

A study was conducted to predict indoor ventilation, smoke movement and fire propagation in a new building currently under construction at the Ecole Polytechnique de Montreal. It was conducted in response to concerns regarding the impact that air quality, in normal operation conditions, and smoke concentration, in the event of a fire, may have on occupants of a building. A detailed three-dimensional model of the new building was constructed using the NURBS-based modeler, Rhino. Simulations of fire propagation and airflow ventilation were performed in different areas of the building. The flow pattern data was analyzed using the computational fluid dynamics (CFD) program called FLUENT. It predicted air flow conditions and estimated the mean age of air (MAA) in the room. Real-world geometries, such as diffuser inlets, have a significant impact on overall fluid flow behaviour and are ...

Energy Technology Data Exchange (ETDEWEB)

Real-time neutron radiography is being evaluated for studying the dynamic behavior of two phase flow and for measuring void fraction in vertical and inclined water ducts. This technique provides a unique means of visualizing the behavior of fluid flow inside thick metal enclosures. To simulate vapor conditions encountered in a fluid flow duct, an air-water flow system was constructed. Air was injected into the bottom of the duct at flow rates up to 0.47 I/s (1 cfm). The water flow rate was varied between 0--3.78 I/m (0--1 gpm). The experiments were performed at the Pennsylvania State University nuclear reactor facility using a real-time neutron radiography camera. With a thermal neutron flux on the order of 10{sup 6}n/cm{sup 2}/s directed through the thin duct dimension, the dynamic behavior of the air bubbles was ...

International Nuclear Information System (INIS)

Transients induced in nuclear power plants from many sources result in one or more fluid conditions changing with time. Fluid conditions of pressure, inlet temperature, inlet flow, or even system power many change separately or in conjunction with each other. The result of the condition change may be one which induces departure from nucleate boiling. An experimental investigation of transient which were intended to achieve Critical Heat Flux was performed at the Heat Transfer Research Facility of Columbia University for Siemens Nuclear Power Corporation. The transients were set up to include broad ranges of flow and pressure conditions near the operating range of pressurized water reactors. Transient events were dominated by varying single conditions and measuring the response of the system and of the rod thermocouples. Because of coupling effects within the test loop, secondary conditions would also ...

UK PubMed Central (United Kingdom)

Nucleic acids are molecules of choice for both established and emerging nanoscale technologies. These technologies benefit from large functional densities of ‘DNA processing elements’...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

In a breeder-type nuclear power plant, liquid metal is used as a coolant due to the high heat capacity factor. Also, some proposals for fusion reactor blanket design include liquid metal as a possible coolant. In both cases the understanding of natural circulation of liquid-metal flow behavior is an integral part of the thermal hydraulic analysis, especially under two-phase flow conditions. Experimental investigations have been conducted to study a liquid metal two-phase natural circulation flow system. A lead-bismuth (PbBi) eutectic mixture is used as a working fluid in a heated metal walled natural circulation loop. Gas injection induces natural circulation through the gas-lift mechanism. A real-time neutron radiography system is used to visualize the two-phase mixture, specifically the interface and the flow regime. Measurements of void fraction, void fluctuation and bubble ...

International Nuclear Information System (INIS)

Experimental and theoretical work have been carried out to find out the effects of heat transfer augmentation on two-phase flow instabilities in a single channel system. The effect of mass flow rate, heat input and inlet subcooling on the system behavior is studied using Freon-11 as the test fluid and six different heater surfaces are tested at various experimental conditions. Experimental evaluation is done using the steady-state pressure drop versus mass flow rate curves along with the curves of additional inlet pressure drop required to stabilize the system during the oscillations, and tables generated using the experimental data. Homogeneous equilibrium flow model and finite differences are used in theoretical analysis. An empirical relationship is obtained to calculate the pressure drop across the exit restriction. Characteristic equation for the system is found by linearizing ...

Energy Technology Data Exchange (ETDEWEB)

In order to study the two-phase natural circulation and flow termination during a small break loss of coolant accident in LWR, simulation experiments have been performed. Based on the two-phase flow scaling criteria developed under this program, an adiabatic hot leg U-bend simulation loop using nitrogen gas and water and a Freon 113 boiling and condensation loop were built. The nitrogen-water system has been used to isolate key hydrodynamic phenomena from heat transfer problems, whereas the Freon loop has been used to study the effect of phase changes and fluid properties. Various tests were carried out to establish the basic mechanism of the flow termination and reestablishment as well as to obtain essential information on scale effects of parameters such as the loop frictional resistance, thermal center, U-bend curvature and inlet geometry. In addition to the above experimental study, a preliminary ...

Energy Technology Data Exchange (ETDEWEB)

The study of natural convection flow and heat transfer within a cylindrical annulus has received considerable attention because of its numerous applications, such as in nuclear reactor design, electronic component cooling, thermal storage systems, energy conservation, energy storage, and energy transmission. Here, the effects of multiple geometric perturbations on the inner and outer cylinders of an annulus with impermeable end walls are investigated in this work. A three-dimensional study was done using a numerical scheme based on a Galerkin method of finite element formulation. The nature of the buoyancy-induced flow field has been analyzed in detail. The flow fields for the cases considered were found to be qualitatively similar, and the introduction of each additional perturbation altered the flow field in a regular and recurring manner. The introduction of each perturbation on the outer cylinder ...

International Nuclear Information System (INIS)

We simulate mountain-scale coupled heat transfer and gas flow at Yucca Mountain. A coupled rock-gas flow and heat transfer model, TGIF2, is used to simulate mountain-scale two-dimensional transient heat transfer and gas flow. The model is first verified against an analytical solution for the problem of an infinite horizontal layer of fluid heated from below. Our numerical results match very well with the analytical solution. Then, we obtain transient temperature and gas flow distributions inside the mountain. These distributions are used by a transient semianalytical particle tracker to obtain carbon-14 travel times for particles starting at different locations within the repository. Assuming that the repository is filled with 30-year-old waste at an initial areal power density of 57 kw/acre, we find that repository temperatures remain above 60 degrees C for more than 10,000 years. ...

International Nuclear Information System (INIS)

We investigated a method of analyzing the hemodynamics of the lung mass by contrast enhanced dynamic computed tomography (dynamic CT) to determine the difference in vascular supply between the pulmonary artery and bronchial artery using an experimental model. Our experimental model consisted of two injectors connected to two tubes, representing the pulmonary artery and bronchial artery, which were further connected to a chamber representing the lung mass. Following infusion of contrast medium into each tube with some delay time, dynamic CT scans were performed to obtain time density curves of the two tubes and the chamber. Using the time-density curve of contrast passage, flow rates from the two tubes into the chamber were calculated by the curve fitting method. Calculated values correlated well with the adopted flow rates of fluid from the injectors (r=0.893) in the experiment. The results indicate our method of ...

International Nuclear Information System (INIS)

A glass furnace, consisting of a combustion space and a glass melter, uses combustion heat to melt sand and cullet into liquid glass to make products. Glass quality is mainly dependent on the temperature, glass composition, and the level of impurities in a glass melter, which include solid batch/cullet particles, liquid glass, and gas bubbles. A comprehensive computational model using an Eulerian approach has been developed to simulate multiphase flows in a glass melter. It includes all the phases, divides solid particles or gas bubbles into various size groups, and treats each group as a continuum. The derived mass, momentum, and energy conservation equations of the flow are solved for local properties for each phase. The simulation considers the heating and melting of the batch (mainly from the radiative heat from combustion and from the convective heat from the molten glass), the formation and transport of bubbles, and the heating and mixing ...

Science.gov (United States)

A computational fluid dynamics (CFD) is coupled with a computational structural dynamics (CSD) to simulate the unsteady rotor flow with aeroelasticity effects. An unstructured upwind Navier-Stokes solver was developed for this simulation, with 2nd order time-accurate dual-time stepping method for temporal discretization and low Mach number preconditioning method. For turbulent flows, both the Spalart-Allmaras and Menter's SST model are available. Mesh deformation is achieved through a fast dynamic grid method called Delaunay graph map method for unsteady flow simulation. The rotor blades are modeled as Hodges & Dowell's nonlinear beams coupled flap-lag-torsion. The rotorcraft computational structural dynamics code employs the 15-dof beam finite element formulation for modeling. The structure code was validated by comparing the natural frequencies of a rotor model with UMARC. The ...

International Nuclear Information System (INIS)

Two-phase flow, thermal management systems are currently being considered as an alternative to conventional, single phase systems for future space missions because of their potential to reduce overall system mass, size, and pumping power requirements. Knowledge of flow regime transitions, heat transfer characteristics, and pressure drop correlations is necessary to design and develop two-phase systems. This work is concerned with microgravity, two-phase flow regime analysis. The data come from a recent sets of experiments. The experiments were funded by NASA Johnson Space Center (JSC) and conducted by NASA JSC with Texas A ampersand M University. The experiment was on loan to NASA JSC from Foster-Miller, Inc., who constructed it with funding from the Air Force Phillips Laboratory. The experiment used R12 as the working fluid. A Foster-Miller two phase pump was used to circulate the two phase mixture and ...

CERN Document Server

We consider Bianchi VI spacetime, which also can be reduced to Bianchi types VI0-V-III-I. We initially consider the most general form of the energy-momentum tensor which yields anisotropic stress and heat flow. We then derive an energy-momentum tensor that couples with the spatial curvature in a way so as to cancel out the terms that arise due to the spatial curvature in the evolution equations of the Einstein field equations. We obtain exact solutions for the universes expanding with constant deceleration parameter. The solutions are reduced to each Bianchi type. The dynamics of the models and fluid are examined briefly, and the models that can approach to isotropy are determined.

International Nuclear Information System (INIS)

In this paper, numerical simulation of a concentric tube heat exchanger is presented to determine the convective heat transfer coefficient and friction factor in a smooth tube. Increasing the convective heat transfer coefficient can increase heat transfer rate in a concentric tube heat exchanger from a given tubular surface area. This can be achieved by using heat transfer augmentation devices. This work constitutes the initial phase of the numerical simulation of heat transfer from tubes employing augmentation devices, such as twisted tapes, wire-coil inserts, for heat transfer enhancement. A computational fluid dynamics (CFD) simulation tool was developed with CFX software and the results obtained from the simulations are validated with the empirical correlations for a smooth tube heat exchanger. The difficulties associated with the simulation of a heat exchanger augmented with wire-coil inserts are discussed. (author)

Science.gov (United States)

Forced convective heat transfer in a cross-corrugated channel solar air heater has been studied experimentally using air as a working fluid. The channel was formed by two transversely positioned corrugated sheets and two flat thermally insulated side walls. One corrugated sheet was heated by a radiant heater, while the other was thermally insulated. The fluid velocity and temperature, and the wall temperature and the local heat flux across the heated corrugated sheet were measured for a variety of operating flow rates. Experimental results for the channel geometry have yielded the correlation Nu = 0.0743 (Re)[sup 0.76]. This heat-transfer coefficient is about 2.8 times that of a smooth flat channel. The experiments showed that local heat transfer rate was smaller on the valley of the corrugation than that on the peak. The ratio of the local heat transfer rates on the two locations was related to the Reynolds number.

International Nuclear Information System (INIS)

This paper presents the development of technical requirements for the design of aircraft-mounted sampling equipment for the airborne radioactivity monitoring. A design concept and internal equipments required for the sampling system will be described in detail to provide information for the development of technical requirements for aircraft-mounted sampling equipment. This will be followed by description of the exterior designing process. Difficulties of designing exterior of the sampling system lie in the fluid dynamics performance of the system. The objective of the design is to maximize the suction flow necessary for achieving high efficiency of radionuclide sampling, while minimizing disturbance to the aircraft which carries the system. The design optimization was performed with the computational fluid dynamics (CFD) code FLUENT. The design options considered here were (1) diameter to head ratio of top and back head, ...

Energy Technology Data Exchange (ETDEWEB)

Better understanding and modelling of three-phase flow through porous media is of great interest, especially for improved oil recovery methods such as gas injection processes. Early theoretical and experimental studies have already demonstrated that the wettability characteristics of the solid surface and the spreading characteristics of the fluid system hold the key roles. This observation is confirmed by our theoretical results using DLP theory on the stability and the thickness of static oil films. In most of the works related to three-phase flow processes, homogeneous wettability is assumed. There exist only a few studies demonstrating the tremendous impact of the wettability heterogeneities on gas injection. The objective of the present work is twofold: to demonstrate the effect of small scale wettability heterogeneities on gas injection efficiency, and to develop a tool to predict this impact for various patterns and ...

International Nuclear Information System (INIS)

In this study, a high-resolution characteristic-based finite-volume (FV) method on unstructured grids [Int. J. Numer. Method Eng. 50 (2001) 11; Int. J. Heat Fluid Flow 21 (2000) 432] is extended by a matrix-free implicit dual-time stepping scheme for the numerical simulation of steady and unsteady flow and heat transfer with porous media. The method has been used to study the characteristics of a complex problem: flow and heat transfer in a channel with multiple discrete porous blocks, which was originally proposed by Huang and Vafai [J. Thermophys. Heat Transfer 8 (3) (1994) 563]. In addition, flow and heat transfer in a channel partially or fully filled with porous layers and containing solid protruding blocks with constant heat flux on its lower surface are also investigated in details. Hydrodynamic and heat transfer results are reported for both steady and transient ...

Energy Technology Data Exchange (ETDEWEB)

Sudden changes in the temperature of flowing liquids can result in transient buoyancy forces which strongly impact the flow hydrodynamics via flow stratification. These effects have been studied for the case of potential flow of stratified liquids to line sinks, but not for moderator flow in SRS reactors. Standard codes, such as TRAC and COMMIX, do not have the capability to capture the stratification effect, due to strong numerical diffusion which smears away the hot/cold fluid interface. A related problem with standard codes is the inability to track plumes injected into the liquid flow, again due to numerical diffusion. The combined effects of buoyant stratification and plume dispersion have been identified as being important in operation of the Supplementary Safety System which injects neutron-poison ink into SRS reactors to provide safe ...

International Nuclear Information System (INIS)

A theoretical model is presented to describe the electromagnetic, heat transfer and fluid flow phenomena within a magnetron plasma torch and in the resultant plume, by using a commercial computational fluid dynamics (CFD) code FLUENT. Specific calculations are presented for a pure argon system (i.e., an argon plasma discharging into an argon environment), operated in a turbulent mode. An important finding of this work is that the external axial magnetic field (AMF) may have a significant effect on the behavior of arc plasma and thus affects the resulting plume. The AMF impels the plasma to retract axially and expand radially. As a result, the plasma intensity distribution on the cross section of torch seems to be more uniform. Numerical results also show that with AMF, the highest plasma temperature decreases and the anode arc root moves upstream significantly, while the current density distribution at the anode is more ...

Energy Technology Data Exchange (ETDEWEB)

This thesis discusses an advanced dynamical two-dimensional cylinder symmetric model for the high temperature part of the carbothermic silicon metal process, and its computer encoding. The situation close to that which is believed to exist around one of three electrodes in full-scale industrial furnaces is modelled. This area comprises a gas filled cavity surrounding the lower tip of the electrode, the metal pool underneath and the lower parts of the materials above. The most important phenomena included are: Heterogeneous chemical reactions taking place in the high-temperature zone (above 1860 {sup o}C), Evaporation and condensation of silicon, Transport of materials by dripping, Turbulent or laminar fluid flow, DC electric arcs, Heat transport by convection, conduction and radiation. The results from the calculations, such as production rates, gas- and temperature distributions, furnace- and particle geometries, fluid ...

Energy Technology Data Exchange (ETDEWEB)

This paper describes the development of a computational multiphase fluid dynamics (CMFD) model of the Fischer Tropsch (FT) process in a Slurry Bubble Column Reactor (SBCR). The CMFD model is fundamentally based which allows it to be applied to different industrial processes and reactor geometries. The NPHASE CMFD solver [1] is used as the robust computational platform. Results from the CMFD model include gas distribution, species concentration profiles, and local temperatures within the SBCR. This type of model can provide valuable information for process design, operations and troubleshooting of FT plants. An ensemble-averaged, turbulent, multi-fluid solution algorithm for the multiphase, reacting flow with heat transfer was employed. Mechanistic models applicable to churn turbulent flow have been developed to provide a fundamentally based closure set for the equations. In this four-field model ...

Energy Technology Data Exchange (ETDEWEB)

A multi-faceted research program has been performed to investigate in detail several aspects of free and forced convective cooling of underground electric cable systems. There were two main areas of investigation. The first one, reported in Volume 1, dealt with the fluid dynamic and thermal aspects of various components of the cable system. In particular, friction factors for laminar flow in the cable pipes with various configurations were determined using a finite element technique; the temperature distributions and heat transfer in splices were examined using a combined analytical numerical technique; the pressure drop and heat transfer characteristics of cable pipes in the transitional and turbulent flow regime were determined experimentally in a model study; and full-scale model experimental work was carried out to determine the fluid dynamic and thermal characteristics of entrance and exit chambers ...

British Library Electronic Table of Contents (United Kingdom)

Mixed convection heat transfer from longitudinal fins inside a horizontal channel has been investigated in the natural convection dominated region for a wide range of Rayleigh numbers and different fin heights and spacings. An experimental parametric study was made to investigate effects of fin spacing, fin height and magnitude of heat flux on mixed convection heat transfer from rectangular fin arrays heated from below in a horizontal channel. The optimum fin spacing to obtain maximum heat transfer has also been investigated. During the experiments constant heat flux boundary condition was realized and air was used as the working fluid. The velocity of fluid entering channel was kept nearly constant (0.02win0.025m/s) using a flow rate control valve so that Reynolds number was always about ...

Energy Technology Data Exchange (ETDEWEB)

The computer programme COMMIX-2 describes steady state and transient multidimensional single- and two-phase fluid flows with heat transfer in nuclear reactor components and multicomponent systems. Originally from the Argonne National Laboratory, the code has been further developed at the Kernforschungszentrum Karlsruhe. The original Point-SOR iterative method for the solution of a Poisson-like equation describing the pressure distribution in the fluid as well as the transport of enthalpy and turbulent quantities has been complemented with iterative and direct line- and block-methods. None of the newly implemented methods is original in itself but their implementation into the computer code, which can describe the most general shapes of definition domains, gave a code speed-up by a factor of 2-5, depending on the problem treated. The code capabilities are assessd by the calculation of a benchmark problem involving the ...

Energy Technology Data Exchange (ETDEWEB)

A novel two-phase flow management process useful for active thermal power rejection in space is introduced. The process serves as a condenser in a Rankine cycle and is applicable for thermal energy management needs in low gravity environments. Benefit is derived from the ability to utilize the high specific energy transport capability of two-phase flow, while not requiring mass-intensive solutions nor complex control strategies to maintain design energy balance integrity. Initial design calculations for a hypothetical space vapor cycle demonstration experiment were done and a steady-state computer model of the novel condensing process was created and used to evaluate its potential to maintain the design energy balance of the experiment. The experiment (approximately 28 kg) was a supercritical organic thermal loop operating between 500 and 400 Kelvin at a mass flow of 1 grain per second; using R-113 as the working ...

International Nuclear Information System (INIS)

It is one of the most important subjects to estimate the flow-related stability of the heat exchanger tubes. A large scale model steam generator has been developed to verify the stability of the tubes in the Japanese PWR steam generators for the two-phase flow-induced vibration and to accumulate related technical data of thermal-hydraulic and flow-induced vibration of U-bend tube bundle. The model steam generator has 230 U-bend tubes of 46 different radius and 5 columns for each of practical diameter and material, and the anti vibration bars are inserted into each spacing between tube arrays. The freon R123 has been used as the secondary side fluid in stead of water-steam two-phase. In the test, void fraction and interfacial velocities in U-bend and straight tube-bundle are measured with bi-optical probes, and vibration responses of some selected tubes are measured with strain gauges and accelerators. ...

Energy Technology Data Exchange (ETDEWEB)

The accurate prediction of local hot spot during normal operation is important to ensure core thermal margin in a very high temperature gas-cooled reactor because of production of its high temperature output. The active cooling of the reactor core determining local hot spot is strongly affected by core bypass flows through the inter-column gaps between graphite blocks and the cross gaps between two stacked fuel blocks. The bypass gap sizes vary during core life cycle by the thermal expansion at the elevated temperature and the shrinkage/swelling by fast neutron irradiation. This study is to investigate the impacts of the variation of bypass gaps during core life cycle as well as core restraint mechanism on the amount of bypass flow and thus maximum fuel temperature. The core thermo fluid analysis is performed using the GAMMA+ code for the PMR200 block-core design. For the analysis not only are some modeling features, ...

International Nuclear Information System (INIS)

The radio, optical, x-ray and gamma-ray nebulae that surround many pulsars are thought to arise from synchrotron and inverse Compton emission. The energy powering this emission as well as the magnetic fields and relativistic particles are supplied by a 'wind' driven by the central object. The inner parts of the wind can be described using the equations of MHD, but these break down in the outer parts, when the density of charge carriers drops below a critical value. This paper reviews the wave properties of the inner part (striped wind), and uses a relativistic two-fluid model (cold electrons and positrons) to re-examine the nonlinear electromagnetic modes that propagate in the outer parts. It is shown that in a radial wind, two solutions exist for circularly polarized electromagnetic modes. At large distances one of them turns into a freely expanding flow containing a vacuum wave, whereas the other decelerates, corresponding to a confined ...

Energy Technology Data Exchange (ETDEWEB)

This paper discusses the application of a Computational Fluid Dynamics (CFD) code (FLUENT) to predict temperature and velocity profiles, and particle trajectories in an industrial fired by a low NO{sub x} pulverized coal swirl burner. The predictions of the code were compared to experimental measurements of gas temperature, particle size distribution, and particle velocities. The diagnostics employed were a suction pyrometer and a Particle Counter Sizer Velocimeter Probe (PCSV-P). Good agreement was found between the temperature predictions and the measurements. In situ particle size distributions were predicted accurately using the Baum and Street model with a swelling factor of zero. The numerical modeling indicated that the Type II flow issued from the burner could be transformed into Type III flow, by eliminating swirl from the primary air stream, which provided the preferred particle trajectories and increased the ...

Science.gov (United States)

Flow cytometric techniques were used to measure the cytological and biochemical damage to respiratory tract cells in animals exposed to particulates. Hamsters were exposed to raw and spent oil shale particulates and silica by intratracheal instillation. Exfoliated lung cells were obtained by sacrificing the animals and lavaging the respiratory tract posterior to the trachea with saline. Cell samples were fixed in ethanol and stained with mithramycin for fluorescence analysis of DNA content. DNA content distributions from hamsters exposed to spent oil shale and silica particulates showed atypical changes 28 to 35 days later. Cell counts and total numbers of macrophages, leukocytes, and epithelial cells in the lavage fluid also showed marked changes related to time after exposure.

British Library Electronic Table of Contents (United Kingdom)

The present investigation is concerned with the effect of Hall currents on boundary layer flow, and heat and mass transfer of an electrically conducting fluid over an unsteady stretching sheet in the presence of a strong magnetic field. The electron-atom collision frequency is assumed to be relatively high, so that the Hall effect is assumed to exist, while the induced magnetic field is neglected. The governing time-dependent boundary layer equations for momentum, thermal energy, and concentration are reduced using a similarity transformation to a set of coupled ordinary differential equations. The similarity ordinary differential equations are then solved numerically by the successive linearization method together with the Chebyshev pseudo-spectral collocation method. Effects of the Prand...

British Library Electronic Table of Contents (United Kingdom)

In this paper, the unsteady MHD free convection heat and mass transfer of viscous fluid flowing through a Darcian porous regime adjacent to a moving vertical semi-infinite plate under Soret and Dufour effect have been examined. Viscous dissipation effects are included in the energy equation. A uniform magnetic field is applied transversely to the direction of the flow. The differential equations governing the problem have been transformed by a similarity transformation into a system of non-dimensional differential equations which are solved numerically by element free Galerkin method. The influence of Grashof number (Gr), magnetic parameter (M), heat absorption parameter (Q), permeability parameter (K), Schmidt number (Sc), Soret number (Sr), and Dufour number (Du) on the velocity, tempera...

International Nuclear Information System (INIS)

Natural convection of vaporizing Deuterium at 25 K transports the heat generated in the moderator cell of the cold neutron source to a He cooled condenser. The thermohydraulics of this thermosiphon were precalculated and the results verified by experiments in a 1:1 model using D_2 as fluid. The experimental results show that the thermosiphon operates stable. The demanded liquid content of the cell as well as wall temperatures below 50 K can be ensured by a proper design of the cell outlet flow geometry. A 7 min. loss of cryogenic power results in transient temperatures of the cell wall of not more than 300 K.

Energy Technology Data Exchange (ETDEWEB)

In reservoir fluid flow, the situation described by an increase in nonwetting phase saturation followed by an increase in wetting phase saturation causes a relative permeability hysteresis effect that is well known. This paper presents a method which allows the calculation of imbibition relative permeability starting at any saturation. The data required are the drainage curve, the historical maximum non wetting saturation, and a minimum of one additional point on some corresponding experimental imbibition curve. In this development, all imbibition curves are shown to be parallel. Also significant is the fact that the residual nonwetting phase saturation can be calculated without a complete experimental specification of the imbibition curve. 5 refs.

International Nuclear Information System (INIS)

Extensive experimental and analytical investigations of fluid flow and heat transfer in gas-cooled rod bundles have been carried out. Different bundle geometries with partially or fully roughened rod surfaces were tested in a carbon dioxide loop. An advanced and comprehensive measuring control and instrumentation are important design features of this experiment. Comprehensive thermal hydraulic subchannel analysis computer codes have been developed in order to assist fuel element design calculation for gas-cooled reactors. The experiments, codes and their verification procedure are described and the results of comparisons between measured and calculated pressure and temperature distributions are given. (orig.).

Energy Technology Data Exchange (ETDEWEB)

This paper presents a numerical simulation with the EUROPLEXUS fast dynamics software of a pipe whipping phenomenon occurring in the thermal hydraulic conditions of a loss of coolant accident in a PWR primary circuit. Different physical phenomena take place simultaneously during the rupture and the whipping of the pipe such as plasticity, contact, large displacements, two-phase flow regime and fluid structure interaction. Two kinds of numerical models - a simplified pipeline model and a mixed 1D/3D model - are considered and compared throughout modelling and computation. Numerical results are compared with experimental data belonging to the Aquitaine II test campaign.

Energy Technology Data Exchange (ETDEWEB)

The possibility of switching the heat transfer consists of varying heat transfer surfaces and making the heat transfer temporarily more intensive. Heat tubes prove to be particularly suitable, which must be exposed to a heat carrier fluid or removed from its effect for switching the heat transfer. This report gives a survey of the possibilities of switching heat flows and for making the heat transfer more intensive. Further, the report contains a survey of patents limited to heat transfer in the fields of cooling internal combustion engines and exhaust systems. (orig.) With 17 figs., 183 refs.

Energy Technology Data Exchange (ETDEWEB)

This paper discusses the successful implementation of automatic control in the Wattenberg Gas Field in northern Colorado. Also discussed is the use of solar powered Amocams equipment to affect continuous monitoring and control of these tight gas wells. The control system includes an algorithm which continuously adjusts the production cycling based on changes in the individual well's producing pressures and flow rates. This strategy has been successful in enhancing production and reducing the number of wells logged off due to excessive fluid buildup. The benefits derived from this system are enumerated and the impacts on field operations are discussed.

Scientific Electronic Library Online (English)

Abstract in english A simplified model for drying solids in the constant rate period in a batch fluidised bed was developed.It assumes the bed to be divided into dense and bubble phases with heat and mass transfer between the phases.The model predicts the constant-rate drying period, provided the fluid bed shape and material characteristics are known.The model is compared with experimental data reported in the literature covering a wide range of materials, gas flow rates, column diameters, m (more) aterial hold-ups, air temperatures and humidities.Model predictions compare satisfactorily with the experimental data.

Energy Technology Data Exchange (ETDEWEB)

Several steam generator tube rupture accidents have occurred at plants in the past. In this paper the Computational Multi-Fluid Dynamics (CMFD) investigation of the horizontal steam generator thermal-hydraulics during the tube rupture accident is performed. A guillotine of a steam generator U-tube is assumed with choked flow from the primary to the secondary side of the steam generator. We have computed water and steam velocity fields, steam volume fraction distribution on the steam generator secondary (shell) side, as well as the swell level increase. The simulation results are a support to the safety analyses of the steam generator tube rupture accident. Numerical simulation is performed with the multidimensional multi-fluid modelling approach. The two-phase flow around steam generator tubes in the bundle is modelled by the porous media approach. Interfacial mass, momentum and energy transfer are ...

Science.gov (United States)

According to the LeChatelier-Braun principle, when a closed quiescent system initially in an equilibrium or unstressed steady state is subjected to an externally imposed ``stress'' it responds in a manner tending to alleviate that stress. Use of this entropically based qualitative rule, in combination with the notion of Maxwell thermal stresses existing in nonisothermal gases and liquids, enables one to (i) derive Maxwell's thermal-creep boundary condition prevailing at the boundary between a solid and a fluid (either gas or liquid) and (ii) rationalize the phenomenon of thermophoresis in liquids, for which, in contrast with the case of gases, an elementary explanation is currently lacking. These two objectives are achieved by quantitatively interpreting the heretofore qualitative LeChatelier-Braun notion of stress in the present context as being the fluid's stress tensor, the latter including Maxwell's thermal stress. In effect, thermophoretic ...

International Nuclear Information System (INIS)

Ferrofluids have promising potential for heat transfer applications, since advective transport in a ferrofluid can be readily controlled by using an external magnetic field. However, unlike conventional free or forced convection, ferrohydrodynamic convection is not yet well characterized. A full understanding of the relationship between an imposed magnetic field, the resulting ferrofluid flow, and the temperature distribution is a prerequisite for the proper design and implementation of applications involving thermomagnetic convection. The literature variously assumes constant magnetic fields, does not completely represent the variation in the imposed field, or its descriptions are inaccurate, since the fields do not comply with the Maxwell's equations of electromagnetism. We address this by simulating two-dimensional forced convection heat transfer in a channel with a ferrofluid that is under the influence of a two-dimensional magnetic field created by a ...

Science.gov (United States)

In early 2006 we designed and built low energy consumption, pump-operated system, for dosing of the liquid nutrient in the summer 2006 season. This operated successfully, and the system was used again during the 2007 and 2008 seasons for dosing. During the early winter period, 2008, laboratory tests were made of the liquid nutrient pump system, and it was noted that small amounts of air were being entrained on the suction side of the pump, during conditions when the inlet pressure was low. It was believed that this was the cause of diurnal fluctuations in the flow supplied, characteristic of the 2007 year flow data. Replacement of '0' rings on the inlet side of the pumps was the solution to this problem, and when tested in the field during the summer season, the flow supplied was found to be stable. A decision was made by the IKERT committee at the meeting of 20th to 21st May 2008 (held in Coeur ...

International Nuclear Information System (INIS)

In this paper, a phenomenological model of the thermal hydraulics of convective boiling in the post-critical-heat-flux (post-CHF) regime is developed and discussed. The model was implemented in the TRAC-PF1/MOD2 computer code (an advanced best-estimate computer program written for the analysis of pressurized water reactor systems). The model was built around the determination of flow regimes downstream of the quench front. The regimes were determined from the flow-regime map suggested by Ishii and his coworkers. Heat transfer in the transition boiling region was formulated as a position-dependent model. The propagation of the CHF point was strongly dependent on the length of the transition boiling region. Wall-to-fluid film boiling heat transfer was considered to consist of two components: first, a wall-to-vapor convective heat-transfer portion and, second, a wall-to-liquid heat transfer representing near-wall effects. Each ...

International Nuclear Information System (INIS)

A homogeneous turbulent mixing of coolant flows with different temperatures at the fuel assembly inlets is an important requirement to minimize hot spots in a fuel assembly of a High Performance Light Water Reactor (HPLWR). Therefore, the mixing chamber between lower core plate, flow adjuster and the mixing chamber within the cluster foot piece diffuser have been investigated using the Computational Fluid Dynamics (CFD)-code Fluent 6.1 and its implemented k-#epsilon# model. The previously presented 3D-CAD-geometry has been simplified using Gambit 2.1.2 and consists of various inlet and outlet tubes or channels in the foot piece bottom plate, the lower core plate and the flow adjuster establishing the boundaries of two consecutive mixing chambers. The temperature distribution at the inlet of the sub-channels of the cluster fuel assemblies is presented. It reveals temperature variations at the coolant ...

Energy Technology Data Exchange (ETDEWEB)

Three instruments for measuring local velocities in liquid-metal MHD experiments for fusion blanket applications are being evaluated. The devices are used in room-temperature NaK experiments to measure three-dimensional flow field patterns anticipated in complex blanket geometries. Hot film anemometry, a standard technique in ordinary fluids, is being used, as well as two developmental devices. One is called the Liquid Metal Electromagnetic Velocity Instrument (LEVI), and performs essentially as a local dc electromagnetic flow meter. The third device, a Thermal Transient Anemometer (TTA) is a rugged, yet relatively simple device, which measures local velocity through the mechanism of convective heat transfer, in some ways similar to hot-film anemometry. Results are presented showing the kinds of data collected this far with each instrument. Measurements include both local velocity measurements and some preliminary frequency ...

Energy Technology Data Exchange (ETDEWEB)

The influence of the velocity profile at the inlet boundary on the simulation of air velocity distribution inside an electrostatic precipitator is presented in this study. Measurements and simulations were performed in a duct and an electrostatic precipitator (ESP). A four-hole cobra probe was used for the measurement of velocity distribution. The flow simulation was performed by using the computational fluid dynamics (CFD) code FLUENT. Numerical calculations for the air flow were carried out by solving the Reynolds-averaged Navier-Stokes equations coupled with the realizable k-{epsilon} turbulence model equations. Simulations were performed with two different velocity profiles at the inlet boundary - one with a uniform (ideal) velocity profile and the other with a non-uniform (real) velocity profile to demonstrate the effect of velocity inlet boundary condition on the flow simulation results inside an ...

International Nuclear Information System (INIS)

The measurement of two-phase flow parameters and development of constitutive relationships for the HANARO/MAPLE type finned fuel using Real-Time Neutron Radiography (RTNR) is discussed in this paper. A single element finned Fuel Element Simulator (FES) was used with R134a Freon as the working fluid. To observe the effect of a spacer device on void distribution, single pin tests were performed with and without a spacer. By analyzing the RTNR images using image processing, the effects of the spacer on the time-averaged and instantaneous void fraction distribution were studied. For the experimental results without a spacer, the time-averaged local void distribution is radially asymmetric and the degree of void fluctuation increases with a decreasing frequency along the heated channel, where the observed asymmetry may be caused by flow induced vibration. For the experimental results with a spacer, the spacer clearly limits any ...

Energy Technology Data Exchange (ETDEWEB)

Numerical investigations of three-dimensional flow and heat transfer in a finned tube with punched longitudinal vortex generators (LVG`s) are carried out for Reynolds number of 250 and 300. Air with a Prandtl number of 0.7 is used as the fluid. The flow is both thermally and hydrodynamically developing. The LVG is a delta winglet pair (DWP) punched out of the fin and is located directly behind the tube, symmetrically separated by one tube diameter. The DWP generates longitudinal vortices in the wake of the tube, defers flow separation on the tube, deflects the main stream into the tube wake, and strong reduces the ``dead water zone.`` Heat transfer reversal is avoided by the DWP. Comparison of the span-averaged Nusselt numbers for the fin with and without DWP shows significant local heat transfer enhancement of several hundred percent in the tube wake. For Re = 300 and Fi = 200 the global heat transfer ...

Energy Technology Data Exchange (ETDEWEB)

Full text of publication follows:In the current thermal-hydraulic system analysis codes using the two-fluid model, the empirical correlations that are based on the two-phase flow regimes and regime transition criteria are being employed as closure relations for the interfacial transfer terms. Due to its inherent shortcomings, however, such static correlations are inaccurate and present serious problems in the numerical analysis. In view of this, a new dynamic approach employing the interfacial area transport equation has been studied. The interfacial area transport equation dynamically models the two-phase flow regime transitions and predicts continuous change of the interfacial area concentration along the flow field. Hence, when employed in the thermal-hydraulic system analysis codes, it eliminates artificial bifurcations stemming from the use of the static flow regime transition ...

Energy Technology Data Exchange (ETDEWEB)

The Hyperion project was developed to determine an algorithm for assessing the risk of hydrate plug formation in the pipeline transport oil-water-gas mixtures at low temperatures. The project is a collaboration between physicists, chemists and engineers within the petroleum industry. This paper provided an overview of the project and outlined results obtained as the project entered its third and final year. The main objective of the project has been to understand the inherent mitigation effects of some oils on gas hydrate formation as well as to develop methods of predicting the risk of hydrate plugging. To date, the project has extracted and studied natural inhibiting components (NICs) in oils. Molecular modelling techniques have been used to study hydrate and fluid interfaces in order to estimate the driving force of agglomeration and growth through mechanical surface stress and measurement of surface wave fluctuations. A scheme is also being developed measure ...

Energy Technology Data Exchange (ETDEWEB)

Beyond a great number of applications in mineral process, the hydrocyclone separation has been used recently in an increasing number of fields, such as: environmental engineering, petrochemical engineering, food engineering, electrochemical engineering, pulp bioengineering, processes and paper industries, among others. Nowadays, the produced water is treated and then reinjected in the surface and also in return to the formation. In the offshore platforms, the produced water can be directly discarded in the ocean, since the dispersed phase concentration (oil) is according to Brazilian regulating agency limits. The basic principle used in hydrocyclone separation is the centrifugal sedimentation machine: the suspended particles are submitted to centrifugal acceleration, which separates them from the fluid. The basic geometry of a hydrocyclone consists of four parts: a cylindrical section for feeding, a conical section for swirling, an overflow and an under ...

British Library Electronic Table of Contents (United Kingdom)

Supercritical fluid extraction from dried banana peel (Musa spp., subgroup Prata, genomic group AAB, popularly known in Brazil as Enxerto) was studied. The aspects investigated were: overall extraction curve (OEC), mass transfer modeling of the yield curves, economical analysis of the process and phase equilibrium data for the pseudo-ternary system of banana peel extract, carbon dioxide and ethanol. The extraction operating conditions evaluated were: pressure ranging from 100bar to 300bar, temperature from 40 to 50^oC and constant solvent flow rate of 5.0gCO2/min. Experimental extraction data were correlated using three kinetic models based on mass transfer equations (logistic, diffusion and Esquivel models). Phase equilibrium measurements were performed using pressure from 64.9bar to 239....

International Nuclear Information System (INIS)

Neutron radiography is a non-destructive test method to examine a material by using the dependency of neutron attenuation on the nuclear characteristics of the atoms composing the object material. There are two categories of neutron radiography; static neutron radiography and dynamic neutron radiography. The static neutron radiography is a technique to observe a standing object by using a camera or a film cassette. The dynamic neutron radiography(DNR) is a technique to observe a moving object usually by using a camera. Depending on the camera frame rate, the dynamic neutron radiography is categorized into the real time neutron radiography(RTNR) and the high speed neutron radiography(HSNR). The frame rate for RTNR is 30 frames/s and that for HSNR is usually more that 500 frames/sec. Thus, RTNR is good for observing time-averaged phenomena and HSNR is good for observing instantaneous phenomena. DNR is a powerful tool for fluid visualization as well as the multi-phase ...

Energy Technology Data Exchange (ETDEWEB)

This patent describes a nuclear system comprising a containment airspace in which a nuclear reactor pressure vessel is disposed there being a reactor core within the pressure vessel. It comprises a heat exchanger elevated a distance above the pressure vessel; a pool of water surrounding the heat exchanger; means for venting the pool of water to an environment outside the containment; a heat exchanger entry conduit within the containment, the entry conduit having an open lower end communicating with the containment space, and an upper end connected to the heat exchanger, water-containing heated fluid present in the containment airspace incident a pressure vessel loss of coolant event entering and flowing through the entry conduit into the heat exchanger for cooling the fluid to convert water vapor therein to a condensate and separate non-condensable gasses therefrom; a gravity driven cooling water pond-containing space, the ...

Energy Technology Data Exchange (ETDEWEB)

A method is described for testing a diverter system on an offshore drilling rig of a type having a marine riser assembly extending to a subsea well, the diverter system having a packer element and at least one port located below the packer element for the passage of drilling fluid flowing upward from the marine riser assembly during drilling. The method consists of connecting a tubular member to the upper end of a packer having an elastomeric expansive seal element; placing the packer in an upper portion of the marine riser assembly below the diverter system and expanding the seal element against the interior of the upper portion; closing the packer element of the diverter system around the tubular member; and finally applying fluid pressure in the space between the packer element of the diverter system and the seal element of the packer to determine if any leakage in the diverter system exists. The patent also describes an ...

International Nuclear Information System (INIS)

The natural convection characteristics of gas in a vertical narrow annular gap which had its bottom opened to high temperature fluid and its upper shielding exposed to low temperature sealant have been evaluated from simulated fluid experiments using water and from calculations using the three-dimensional thermal hydraulic analysis computer code THERVIS-III. The following results were obtained: (1) The critical Rayleigh number which represented the limit of convection generation increased as the aspect ratios #epsilon#_1 (height/circumference) and #epsilon#_2 (height/gap distance) increased. (2) The flow pattern along the circumferential direction was seen to depend more strongly on the radiant heat from the side wall, rather than the aspect ratios #epsilon#_1 and #epsilon#_2. (3) The temperature difference along the circumferential direction in the annular gap obtained from the calculation code coincided with that obtained ...

International Nuclear Information System (INIS)

The Supercritical Water Cooled Reactor(SCWR) operates in a pressure around 25MPa and temperature of 293#approx#510 .deg. C. In order to study the heat transfer behaviors and good comparisons between the various fluids, a heat transfer test loop(SPHINX) using CO_2 has been constructed in KAERI as a part of international research program, I-NERI. At a supercritical pressure, the heat transfer coefficient is much larger than that estimated from the Dittus-Boelter correlation for a relatively large flow rate with moderate wall heat flux conditions. This phenomenon was explained by the rapid variations of the physical properties near the wall with the temperature. On the contrary, the heat transfer becomes worse when the bulk fluid enthalpy is below the pseudo-critical enthalpy under a low flow rate with large heat flux conditions. This phenomenon is called 'deteriorated heat transfer', and which is ...

Energy Technology Data Exchange (ETDEWEB)

Full text of publication follows: A porous media solution PORFLO has been developed for the 3-dimensional two-phase flow by describing the process facility in Cartesian or cylindrical coordinates. The local porosity fraction is applied for distinguishing the fluid filled volumes from the solid structures. The solid structure contribute the two-phase flow through the wall friction, flow area and heat transfer. Optionally the solid structure may contain primary liquid of steam generators, steam in the higher temperature and pressure to be condensed or electrical heating power. By using these optional boundary conditions three different process facilities have been analysed. The thermohydraulic solution based on 5-equation approach, where the conservation equations are solved for the liquid and gas (vapour) mass, mixture momentum (giving the velocity only for the mixture), liquid and gas energy, is ...

Science.gov (United States)

The GEOFLOW I experiment has been successfully performed on the International Space Sta-tion (ISS) in 2008 in the Columbus module in order to study the stability, pattern formation and transition to turbulence in a viscous incompressible fluid layer enclosed in two concentric co-rotating spheres subject to a radial temperature gradient and a radial volumetric force field. The objective of the study is the experimental investigation of large scale astrophysical and geophysical phenomena in spherical geometry stipulated by rotation, thermal convections and radial gravity fields. These systems include earth outer core or mantle convection, differen-tial rotation effects in the sun, atmosphere of gas planets as well as a variety of engineering applications. The GEOFLOW I experimental instrument consists of an experiment insert for operation in the Fluid Science Laboratory, which is part of the Columbus Module of the ISS. It was first launched in ...

International Nuclear Information System (INIS)

An experimental program has been conducted to determine the feasibility of natural convection cooling of a reactor following a beyond-design-based accident. The particular application under consideration was the heavy-water new production reactor. The questions to be resolved include the verification that a natural convection cooling pattern would be established and the determination of the power limit for which convective cooling will occur for a significant period of time. In the experiment, the reactor configuration was simulated using small-diameter vertical heated tubes in parallel with a large-diameter bypass line. Following a loss-of-flow event, the flow in the bypass line will reverse direction and pass through the heated channel by means of natural convection. If, however, the channel power is too high, void formation will block the channel and prevent the reverse flow pattern from occurring. The test procedure ...

Science.gov (United States)

Three-dimensional computer simulation and analyses of the horizontal steam generator thermal-hydraulics of the WWER 1000 nuclear power plant have been performed for 50% and 75% partial loads, 100% nominal load and 110% over-load. Presented results show water and steam mass flow rate vectors, steam void fraction spatial distribution, recirculation zones, swell level position, water mass inventory on the shell side, and other important thermal-hydraulic parameters. The simulations have been performed with the computer code 3D ANA, based on the 'two-fluid' model approach. Steam-water interface transport processes, as well as tube bundle flow resistance, energy transfer, and steam generation within tube bundles are modelled with {sup c}losure laws{sup .} Applied approach implies non-equilibrium thermal and flow conditions. The model is solved by the control volume procedure, which has been ...

Energy Technology Data Exchange (ETDEWEB)

Small circular and noncircular channels are representative of flow passages in compact evaporators and condensers. This paper describes results of an experimental study on heat transfer to the flow boiling of refrigerant- 12 in a small circular tube of diameter = 2.46 mm. The objective of the study was to assess the effect of channel size on the heat transfer coefficient and to obtain additional insights relative to the heat transfer mechanisms. The flow channel was made of brass and had an overall length of 0.9 m. The channel wall was electrically heated, and temperatures were measured on the channel wall and in the bulk fluid stream. Voltage taps were located at the same axial locations as the stream thermocouples to allow testing over an exit quality range of 0.21 to 0.94 and a large range of mass flux (63 to 832 kg/m{sup 2}s) and heat flux (2.5 to 59 kW/m{sup 2}). Saturation pressure was nearly ...

International Nuclear Information System (INIS)

Power Fluidic systems for the control of liquids and gaseous flows have been adopted for use in radioactive processing plants in the UK. These devices are intrinsically reliable with no mechanical moving parts because they are able to make use of the hydrodynamics of the fluids being controlled. This reliability feature leads to a zero cell maintenance concept and the elimination of mechanical drive/control systems in cell. The first phase of the development work led to their use in the Fast Reactor Reprocessing Plant at Dounreay and the Highly Active Liquor Storage facility at Sellafield. The success of these early developments has led to an extensive development programme for an extended range of applications in the Thermal Oxide Reprocessing Plant and its associated waste treatment facilities at Sellafield. The technology has now been fully demonstrated and adopted for these plants with considerable benefit over a wide range of applications.

Energy Technology Data Exchange (ETDEWEB)

Fugitive dust emissions from stockpiles in the open storage yards of industrial zones and the subsequent atmospheric dust dispersion have brought about many ecological and economical problems. This paper introduces a new approach to reduce pollutant emissions by simply changing pile configuration and without affecting the operational activity on these parks. Flow around piles of different geometries and for various wind conditions was studied using previously validated Computational Fluid Dynamic (CFD) simulations. Different pile height scenarios were investigated corresponding to a constant material volume and a fixed angle of repose under various wind magnitudes. The results obtained were integrated in order to evaluate the rate of dust emissions for the various configurations considered. It was found that, for the range of wind conditions and pile dimensions tested, an optimal geometry exists which corresponds to the lower emissions rate. 13 ...

Energy Technology Data Exchange (ETDEWEB)

Within the framework of efforts to optimize state-of-the-art waste disposal methods, this research project makes a theoretical analysis of the propagation behaviour of pollutants from landfills and waste incineration plants into the immediate vicinity of such plants. In order to judge the propagation of pollutants near the above-mentioned waste disposal facilities, a calculation program was developed within the framework of this research project which permits simulation of the propagation of such emissions in a three-dimensional space by application of an Eulerian grid model. It is capable of realistically representing fluid flow conditions and pollutant concentrations for certain points of times within the complex building patterns of such plants, for randomly chosen atmospheric conditions. (orig.)

International Nuclear Information System (INIS)

'Glass Earth' represents a number of current and planned projects within CSIRO aimed at making 'transparent' the top 1000 m of the Earth's crust It builds upon current technologies developed within a number of CSIRO divisions as well as the Australian Mineral Exploration Technologies CRC (AMET CRC), the Australian Geodynamics CRC (AG CRC) and the CRC for Landscape Evolution and Mineral Exploration (CRC LEME). New geophysical and geochemical technologies will be developed to complement these, together with new capabilities in modelling, data integration and visualisation, including hydrogeochemistry, hydrogeology, surface geochemistry and isotope geochemistry, modelling of chemical, fluid and heat flows in rock and regolith, advanced visualisation and data fusion. This paper describes some recent work in the field of isotope geochemistry, with the principal aim of 'seeing through' cover to understand basement geology and detect hidden ore ...

British Library Electronic Table of Contents (United Kingdom)

The effects of thermal radiation and viscous dissipation on magneto-hydrodynamic (MHD) unsteady free-convection flow over a semi-infinite vertical porous plate are analysed. The fluid considered is non-gray (absorption coefficient dependent on wave length). The Network Simulation Method is used to solve the boundary-layer equations based on the finite-difference formulation; only discretization of the spatial co-ordinates is necessary, while time remains as a real continuous variable. This method provides a solution for both transient and steady-state problems at the same time, and programming does not require manipulation of the sophisticated mathematical software that is inherent in other numerical methods. The velocity, temperature, local skin-friction and local Nusselt number are studi...

CERN Document Server

The Kosambi-Cartan-Chern (KCC) theory represents a powerful mathematical method for the analysis of dynamical systems. In this approach one describes the evolution of a dynamical system in geometric terms, by considering it as a geodesic in a Finsler space. By associating a non-linear connection and a Berwald type connection to the dynamical system, five geometrical invariants are obtained, with the second invariant giving the Jacobi stability of the system. The Jacobi (in)stability is a natural generalization of the (in)stability of the geodesic flow on a differentiable manifold endowed with a metric (Riemannian or Finslerian) to the non-metric setting. In the present paper we review the basic mathematical formalism of the KCC theory, and present some specific applications of this method in general relativity, cosmology and astrophysics. In particular we investigate the Jacobi stability of the general relativistic static fluid sphere with a ...

International Nuclear Information System (INIS)

Heat transfer augmentation based on the process intensification concept in heat exchangers and thermal reactors has received much attention in recent years, mainly due to energy efficiency and environmental considerations. The concept consists of the development of novel apparatuses and techniques that, compared to those commonly used today, are expected to bring dramatic improvements in manufacturing and processing, substantially decreasing equipment size, energy consumption, and ultimately resulting in cheaper, sustainable technologies. The objective of this paper was to investigate the heat transfer characteristics of tubular thermal reactor using static mixing technology. Glycerin and water were used as the test fluids and water was used as the heating source. The results for heat transfer rate were strongly influenced by tube geometry and flow conditions.

British Library Electronic Table of Contents (United Kingdom)

Experimental investigations have been performed to study solutal convection around an air bubble squeezed between the walls of a horizontal rectangular channel, filled by an aqueous solution of surfactant with vertically stratified concentration. A convective motion in the fluid develops due to the solutocapillary Marangoni forces at the bubble lateral free surface. The structure and evolution of the convective flow and the surfactant concentration fields in the channel have been investigated using interferometric technique. The tests revealed the development of self-oscillatory modes near the bubble surface, related to the interaction between solutocapillary and solutogravitational motion mechanisms. The time dependences of the oscillations period are analyzed in relation to the average c...

Energy Technology Data Exchange (ETDEWEB)

A one-dimensional thermal model is derived to describe the temperature field around a vertical borehole heat exchanger (BHEX) for a geothermal heat pump. The inlet and outlet pipe flows are modeled as one, and an effective heat capacity is added to model the heat storage in the fluid and pipes. Parameter estimation techniques are then used to estimate various parameters associated with the model, including the thermal conductivity of the soil and the grout that fills the borehole and surrounds the U-tube. The model is validated using test data from an experimental rig containing sand with known thermal conductivity. The estimates of the sand's thermal conductivity derived from the model are found to be in good agreement with independent measurements.

Energy Technology Data Exchange (ETDEWEB)

Humans are exposed to chemicals in contaminated groundwaters that are used as sources of drinking water. Chemicals contaminate groundwater resources as a result of waste disposal methods for toxic chemicals, overuse of agricultural chemicals, and leakage of chemicals into the subsurface from buried tanks used to hold fluid chemicals and fuels. In the process, both the solid portions of the subsurface and the groundwaters that flow through these porous structures have become contaminated. Restoring these aquifers and minimizing human exposure to the parent chemicals and their degradation products will require the identification of suitable biomarkers of human exposure; better understandings of how exposure can be related to disease outcome; better understandings of mechanisms of transport of pollutants in the heterogeneous structures of the subsurface; and field testing and evaluation of methods proposed to restore and cleanup contaminated ...

British Library Electronic Table of Contents (United Kingdom)

The heat transfer a characteristics and friction factor in the horizontal double pipes of flat tubes with full length helical screw element of different twist ratio and helical screw inserts with different spacer length are investigated. Cold and hot water are used as working fluid in tube side and shell side respectively. The experiments covered a range of Reynolds numbers 5.7x102Re1.31x103. The effect of spacer length on the heat transfer augmentation and friction factor and the effect of twist ratio on heat transfer augmentation and friction factor have been presented separately. The study shows that, the Nusslet number (Nu) and friction factor (f) decrease with the increase of S or Y for flat tube. The comparison between the data of present plain circular with that of previous plain ci...

CERN Document Server

Although hydrogen is the simplest of atoms, it does not form the simplest of solids or liquids. Quantum effects in these phases are considerable (a consequence of the light proton mass) and they have a demonstrable and often puzzling influence on many physical properties, including spatial order. To date, the structure of dense hydrogen remains experimentally elusive. Recent studies of the melting curve of hydrogen indicate that at high (but experimentally accessible) pressures, compressed hydrogen will adopt a liquid state, even at low temperatures. In reaching this phase, hydrogen is also projected to pass through an insulator-to-metal transition. This raises the possibility of new state of matter: a near ground-state liquid metal, and its ordered states in the quantum domain. Ordered quantum fluids are traditionally categorized as superconductors or superfluids; these respective systems feature dissipationless electrical currents or mass ...