WorldWideScience

Sample records for flow chevron nozzles

  1. Acoustic characteristics of the flow over different shapes of nozzle chevrons,

    Directory of Open Access Journals (Sweden)

    Daniel CRUNTEANU

    2013-09-01

    Full Text Available The objective of this paper is to present a comparison between different types of chevrons and their influence on the acoustic power level radiated by the flow over them. The comparison was performed using a two-dimensional simulation of the flow over four different shapes of chevrons resulting propagation of the acoustic waves for each shape. Acoustic characteristics were revealed studying the main flow parameters (pressure, velocity, kinetic energy in order to be able to discover the most efficient shape of chevron regarding the acoustic power level emitted.

  2. PIV Measurements of Chevrons on F400-Series Tactical Aircraft Nozzle Model

    Science.gov (United States)

    Bridges, James; Wernet, Mark P.; Frate, Franco C.

    2011-01-01

    Reducing noise of tactical jet aircraft has taken on fresh urgency as core engine technologies allow higher specific-thrust engines and as society become more concerned for the health of its military workforce. Noise reduction on this application has lagged the commercial field as incentives for quieting military aircraft have not been as strong as in their civilian counterparts. And noise reduction strategies employed on civilian engines may not be directly applicable due to the differences in exhaust system architecture and mission. For instance, the noise reduction technology of chevrons, examined in this study, will need to be modified to take into account the special features of tactical aircraft nozzles. In practice, these nozzles have divergent slats that are tied to throttle position, and at take off the jet flow is highly overexpanded as the nozzle is optimized for cruise altitude rather than sea level. In simple oil flow visualization experiments conducted at the onset of the current test program flow barely stays attached at end of nozzle at takeoff conditions. This adds a new twist to the design of chevrons. Upon reaching the nozzle exit the flow shrinks inward radially, meaning that for a chevron to penetrate the flow it must extend much farther away from the baseline nozzle streamline. Another wrinkle is that with a variable divergence angle on the nozzle, the effective penetration will differ with throttle position and altitude. The final note of realism introduced in these experiments was to simulate the manner in which bypass flow is bled into the nozzle wall in real engines to cool the nozzle, which might cause very fat boundary layer at exit. These factors, along with several other issues specific to the application of chevrons to convergent-divergent nozzles have been explored with particle image velocimetry measurements and are presented in this paper.

  3. PIV Measurements of Chevrons on F400 Tactical Aircraft Nozzle Model

    Science.gov (United States)

    Bridges, James; Wernet, Mark; Frate, Franco

    2010-01-01

    Previous talks at this meeting have covered our collaborative work on high-energy jets such as present in tactical aircraft (those with supersonic plumes). The emphasis of this work is improving our understanding of flow physics and our prediction tools. In this presentation we will discuss recent flow diagnostics acquired using Particle Image Velocimetry (PIV) made on an underexpanded shocked jet plume from a tactical aircraft nozzle. In this presentation we show cross-sectional and streamwise cuts of both mean and turbulent velocities of an F404 engine nozzle with various chevron designs applied. The impact of chevron penetration, length, and width are documented. The impact of the parameters is generally nonlinear in measures considered here, a surprising result given the relatively smooth behavior of the noise to variations in these chevron parameters.

  4. Acoustic control study of turbofan nozzles with triangular chevrons

    Directory of Open Access Journals (Sweden)

    Grigore CICAN

    2014-03-01

    Full Text Available This paper has a small part dealing with the notion of chevron and the process that helps reducing the noise pollution. Based on the gas dynamics and the geometrical parameters of the turbofan jet engine a model of CFD data processing is created. In this process the influence of chevrons on acoustic wave intensity produced by the jet is observed by analyzing this process. A series of tests have been made on 10 si 20 lobed chevrons. The combination between them and the 7 resulting cases have been studied, namely the triangular chevrons in order to settle the influence of the geometrical parameters on the flow and on the jet acoustics. Finally the contribution of the chevrons in noise pollution reduction has been highlighted.

  5. Effect of chevron nozzle penetration on aero-acoustic characteristics of jet at M = 0.8

    Science.gov (United States)

    Nikam, S. R.; Sharma, S. D.

    2017-12-01

    Aero-acoustic characteristics of a high-speed jet with chevron nozzles are experimentally investigated at a Mach number of 0.8. The main focus is to examine the effects of the extent of chevron penetration and its position in the mixing layer. Chevron nozzles with three different levels of penetration employed at three different longitudinal locations from the nozzle lip are tested, and the results are compared with those of a plain baseline nozzle. The chevrons are found to produce a lobed shear layer through the notched region, thereby increasing the surface area of the jet, particularly in the close vicinity of the nozzle, which increases the mixing and reduces the potential core length. This effect becomes more prominent with increasing penetration closer to the nozzle lip in the thinner mixing layer. Near field and far field noise measurements show distinctly different acoustic features due to chevrons. The chevrons are found to effectively shift the dominant noise source upstream closer to the nozzle. Present investigation proposes a simpler method for locating the dominant noise source from the peak of the centerline velocity decay rate. The overall noise levels registered along the jet edge immediately downstream of the chevrons are higher, but further downstream they are reduced in comparison with the plain baseline nozzle. Also, the chevrons beam the noise towards higher polar angles at higher frequencies. At shallow polar angles with respect to the jet axis in the far field, chevrons suppress the noise at low frequencies with increasing penetration, but for higher polar angles, while they continue to suppress the low frequency noise, at higher frequencies the trend is found to reverse. The noise measured in the near field close to the jet edge is composed of two components: acoustic and hydrodynamic. Of these two components, the chevrons are found to reduce the hydrodynamic component in comparison with the acoustic one.

  6. Effect of chevron nozzle penetration on aero-acoustic characteristics of jet at M = 0.8

    Energy Technology Data Exchange (ETDEWEB)

    Nikam, S R [K. J. Somaiya college of Engineering, Mumbai (India); Sharma, S D, E-mail: srnikam12@gmail.com [I.I.T. Bombay, Mumbai (India)

    2017-12-15

    Aero-acoustic characteristics of a high-speed jet with chevron nozzles are experimentally investigated at a Mach number of 0.8. The main focus is to examine the effects of the extent of chevron penetration and its position in the mixing layer. Chevron nozzles with three different levels of penetration employed at three different longitudinal locations from the nozzle lip are tested, and the results are compared with those of a plain baseline nozzle. The chevrons are found to produce a lobed shear layer through the notched region, thereby increasing the surface area of the jet, particularly in the close vicinity of the nozzle, which increases the mixing and reduces the potential core length. This effect becomes more prominent with increasing penetration closer to the nozzle lip in the thinner mixing layer. Near field and far field noise measurements show distinctly different acoustic features due to chevrons. The chevrons are found to effectively shift the dominant noise source upstream closer to the nozzle. Present investigation proposes a simpler method for locating the dominant noise source from the peak of the centerline velocity decay rate. The overall noise levels registered along the jet edge immediately downstream of the chevrons are higher, but further downstream they are reduced in comparison with the plain baseline nozzle. Also, the chevrons beam the noise towards higher polar angles at higher frequencies. At shallow polar angles with respect to the jet axis in the far field, chevrons suppress the noise at low frequencies with increasing penetration, but for higher polar angles, while they continue to suppress the low frequency noise, at higher frequencies the trend is found to reverse. The noise measured in the near field close to the jet edge is composed of two components: acoustic and hydrodynamic. Of these two components, the chevrons are found to reduce the hydrodynamic component in comparison with the acoustic one. (paper)

  7. Flow-throttling orifice nozzle

    International Nuclear Information System (INIS)

    Sletten, H.L.

    1975-01-01

    A series-parallel-flow type throttling apparatus to restrict coolant flow to certain fuel assemblies of a nuclear reactor is comprised of an axial extension nozzle of the fuel assembly. The nozzle has a series of concentric tubes with parallel-flow orifice holes in each tube. Flow passes from a high pressure plenum chamber outside the nozzle through the holes in each tube in series to the inside of the innermost tube where the coolant, having dissipated most of its pressure, flows axially to the fuel element. (U.S.)

  8. Fluid flow nozzle energy harvesters

    Science.gov (United States)

    Sherrit, Stewart; Lee, Hyeong Jae; Walkemeyer, Phillip; Winn, Tyler; Tosi, Luis Phillipe; Colonius, Tim

    2015-04-01

    Power generation schemes that could be used downhole in an oil well to produce about 1 Watt average power with long-life (decades) are actively being developed. A variety of proposed energy harvesting schemes could be used to extract energy from this environment but each of these has their own limitations that limit their practical use. Since vibrating piezoelectric structures are solid state and can be driven below their fatigue limit, harvesters based on these structures are capable of operating for very long lifetimes (decades); thereby, possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. An initial survey [1] identified that spline nozzle configurations can be used to excite a vibrating piezoelectric structure in such a way as to convert the abundant flow energy into useful amounts of electrical power. This paper presents current flow energy harvesting designs and experimental results of specific spline nozzle/ bimorph design configurations which have generated suitable power per nozzle at or above well production analogous flow rates. Theoretical models for non-dimensional analysis and constitutive electromechanical model are also presented in this paper to optimize the flow harvesting system.

  9. Chevron Texaco wants Kazakh oil to flow through Slovakia

    International Nuclear Information System (INIS)

    Janoska, J.

    2004-01-01

    Chevron Texaco is offering Slovakia an option for the diversification of its oil stocks. It plans to use the Druzba pipeline to transport about 3 million tons of Kazakhstan oil. Most of it should be delivered to the refinery in Czech Kralupy. Pipeline administrator, the company Transpetrol, rejects the proposal and argues that adjusting the pipeline designed for heavy Russian oil to allow the transmission of light oil would cost over SKK 2 billion (Eur 50.04 million). Transpetrol is managed by Russian concern Yukos. Russian oil companies view Caspian oil as competition and the reaction of Transpetrol only follows in line with this attitude. It may sound paradoxical, but letting Caspian oil flow through the Transpetrol pipelines would help Russian concerns expand to Western European markets. The refinery in Kralupy is connected to the IKL pipeline, which connects the Czech Republic to the German network close to the German refinery in Ingolstadt. The one-way pipeline that the Czech used to decrease their dependency on Russian oil and the Druzba pipeline in the nineties would remain unused and discussions about an investment in a change of flow direction to allow the transport of oil to Germany would take on an entirely new dimension. The interest of Chevron may therefore indicate major changes in the European oil distribution network. If the flow direction of the IKL pipeline were to change, it would not only be possible to transport Caspian oil, but also Russian oil. What's more, both US and Western European companies have their sights set on Czech and German refineries that get their oil form the Caspian region and they are also interested in capital entry to Russian oil concerns. This scenario is likely to come true in the case of Yukos

  10. Nozzle flow calculation for real gases

    International Nuclear Information System (INIS)

    Bier, K.; Ehrler, F.; Hartz, U.; Kissau, G.

    1977-01-01

    The flow of CHF 2 Cl vapor (refrigerant R 22) through a Laval nozzle of annular geometry has been investigated in the region near the saturation line with stagnation pressures up to 85 per cent of the critical pressure. Static pressure profiles measured along the nozzle axis were found in good agreement with profiles calculated for one-dimensional isentropic flow of the real gas the thermal properties of which were derived from an equation of state proposed previously by Rombusch. Minor deviations between measured and calculated static pressure curves occur in the supersonic part of the mozzle, especially when supersaturated states of the vapour are passed. These deviations can be attributed to uncertainties in the calculation of the enthalpy and to a small influence of the static pressure probe. An additional investigation was concerned with an approximate calculation of the nozzle flow of real gases. In this approximation the well known relations of ideal gas dynamics are applied, the ratio of specific heats for the ideal gas being replaced, however, by a suitably adapted isentropic exponent, which can be determined e.g. from measured values of the Laval pressure or of the mass flow. For pressure ratios p/po between 1 and approximately 0.1, corresponding to Mach numbers up to approximately 2.2, all the interesting properties of the investigated flow of CHF 2 Cl vapour are approximated within a few per cent. (orig.) [de

  11. Flow energy piezoelectric bimorph nozzle harvester

    Science.gov (United States)

    Sherrit, Stewart; Lee, Hyeong Jae; Walkemeyer, Phillip; Hasenoehrl, Jennifer; Hall, Jeffrey L.; Colonius, Tim; Tosi, Luis Phillipe; Arrazola, Alvaro; Kim, Namhyo; Sun, Kai; Corbett, Gary

    2014-04-01

    There is a need for a long-life power generation scheme that could be used downhole in an oil well to produce 1 Watt average power. There are a variety of existing or proposed energy harvesting schemes that could be used in this environment but each of these has its own limitations. The vibrating piezoelectric structure is in principle capable of operating for very long lifetimes (decades) thereby possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. In order to determine the feasibility of using piezoelectrics to produce suitable flow energy harvesting, we surveyed experimentally a variety of nozzle configurations that could be used to excite a vibrating piezoelectric structure in such a way as to enable conversion of flow energy into useful amounts of electrical power. These included reed structures, spring mass-structures, drag and lift bluff bodies and a variety of nozzles with varying flow profiles. Although not an exhaustive survey we identified a spline nozzle/piezoelectric bimorph system that experimentally produced up to 3.4 mW per bimorph. This paper will discuss these results and present our initial analyses of the device using dimensional analysis and constitutive electromechanical modeling. The analysis suggests that an order-of-magnitude improvement in power generation from the current design is possible.

  12. A fundamental study of a variable critical nozzle flow

    International Nuclear Information System (INIS)

    Kim, Jea Hyung; Kim, Heuy Dong; Park, Kyung Am

    2003-01-01

    The mass flow rate of gas flow through critical nozzle depends on the nozzle supply conditions and the cross-sectional area at the nozzle throat. In order that the critical nozzle can be operated at a wide range of supply conditions, the nozzle throat diameter should be controlled to change the flow passage area. This can be achieved by means of a variable critical nozzle. In the present study, both experimental and computational works are performed to develop variable critical nozzle. A cone-cylinder with a diameter of d is inserted into conventional critical nozzle. It can move both upstream and downstream, thereby changing the cross-sectional area of the nozzle throat. Computational work using the axisymmetric, compressible Navier-Stokes equations is carried out to simulate the variable critical nozzle flow. An experiment is performed to measure the mass flow rate through variable critical nozzle. The present computational results are in close agreement with measured ones. The boundary layer displacement and momentum thickness are given as a function of Reynolds number. An empirical equation is obtained to predict the discharge coefficient of variable critical nozzle

  13. Mechanical Chevrons and Fluidics for Advanced Military Aircraft Noise Reduction

    Science.gov (United States)

    2011-03-01

    when viewed as an animation (movie). Representative still-frames from the movies are shown in Figs. 12 and 13. Apart from the features of the flow...Martens, Far-Field Acoustic Investigation into Chevron Nozzle Mechanisms and Trends, AIAA Journal, Vol.43, no.1, pp.87-95, 2004. 10. Panda , J

  14. Reverse flow through a large scale multichannel nozzle

    International Nuclear Information System (INIS)

    Duignan, M.R.; Nash, C.A.

    1992-01-01

    A database was developed for the flow of water through a scaled nozzle of a Savannah River Site reactor inlet plenum. The water flow in the nozzle was such that it ranged from stratified to water solid conditions. Data on the entry of air into the nozzle and plenum as a function of water flow are of interest in loss-of-coolant studies. The scaled nozzle was 44 cm long, had an entrance diameter of 95 mm, an exit opening of 58 mm x 356 mm, and an exit hydraulic diameter approximately equal to that of the inlet. Within the nozzle were three flow-straightening vanes which divided the flow path into four channels. All data were taken at steady-state and isothermal (300 K ± 1.5 K) conditions. During the reverse flow of water through the nozzle the point at which air begins to enter was predicted within 90% by a critical weir-flow calculation. The point of air entry into the plenum itself was found to be a function of flow conditions

  15. Design, fabrication, and testing of a SMA hybrid composite jet engine chevron

    Science.gov (United States)

    Turner, Travis L.; Cabell, Randolph H.; Cano, Roberto J.; Fleming, Gary A.

    2006-01-01

    Control of jet noise continues to be an important research topic. Exhaust nozzle chevrons have been shown to reduce jet noise, but parametric effects are not well understood. Additionally, thrust loss due to chevrons at cruise suggests significant benefit from deployable chevrons. The focus of this study is development of an active chevron concept for the primary purpose of parametric studies for jet noise reduction in the laboratory and technology development to leverage for full scale systems. The active chevron concept employed in this work consists of a laminated composite structure with embedded shape memory alloy (SMA) actuators, termed a SMA hybrid composite (SMAHC). The actuators are embedded on one side of the middle surface such that thermal excitation generates a moment and deflects the structure. A brief description of the chevron design is given followed by details of the fabrication approach. Results from bench top tests are presented and correlated with numerical predictions from a model for such structures that was recently implemented in MSC.Nastran and ABAQUS. Excellent performance and agreement with predictions is demonstrated. Results from tests in a representative flow environment are also presented. Excellent performance is again achieved for both open- and closed-loop tests, the latter demonstrating control to a specified immersion into the flow. The actuation authority and immersion performance is shown to be relatively insensitive to nozzle pressure ratio (NPR). Very repeatable immersion control with modest power requirements is demonstrated.

  16. Characteristics of Multiplexed Grooved Nozzles for High Flow Rate Electrospray

    International Nuclear Information System (INIS)

    Kim, Kyoung Tae; Kim, Woo Jin; Kim, Sang Soo

    2007-01-01

    The electrospray operated in the cone-jet mode can generate highly charged micro droplets in an almost uniform size at flow rates. Therefore, the multiplexing system which can retain the characteristics of the cone-jet mode is inevitable for the electrospray application. This experiment reports the multiplexed grooved nozzle system with the extractor. The effects of the grooves and the extractor on the performance of the electrospray were evaluated through experiments. Using the grooved nozzle, the stable cone-jet mode can be achieved at the each groove in the grooved mode. Furthermore, the number of nozzles per unit area is increased by the extractor. The multiplexing density is 12 jets per cm 2 at 30 mm distance from the nozzle tip to the ground plate. The multiplexing system for the high flow rate electrospray is realized with the extractor which can diminish the space charge effect without sacrificing characteristics of the cone-jet mode

  17. Extending cavitation models to subcooled and superheated nozzle flow

    International Nuclear Information System (INIS)

    Schmidt, D.P.; Corradini, M.L.

    1997-01-01

    Existing models for cavitating flow are extended to apply to discharge of hot liquid through nozzles. Two types of models are considered: an analytical model and a two-dimensional numerical model. The analytical model of cavitating nozzle flow is reviewed and shown to apply to critical nozzle flow where the liquid is subcooled with respect to the downstream conditions. In this model the liquid and vapor are assumed to be in thermodynamic equilibrium. The success of this analytical model suggests that hydrodynamic effects dominate the subcooled nozzle flow. For more detailed predictions an existing multi-dimensional cavitation model based on hydrodynamic non-equilibrium is modified to apply to discharge of hot liquid. Non-equilibrium rate data from experimental measurements are used to close the equations. The governing equations are solved numerically in time and in two spatial dimensions on a boundary fitted grid. Results are shown for flow through sharp nozzles, and the coefficient of discharge is found to agree with experimental measurements for both subcooled and flashing fluid. (author)

  18. Critical flashing flows in nozzles with subcooled inlet conditions

    International Nuclear Information System (INIS)

    Abuaf, N.; Jones, O.C. Jr.; Wu, B.J.C.

    1983-01-01

    Examination of a large number of experiments dealing with flashing flows in converging and converging-diverging nozzles reveals that knowledge of the flashing inception point is the key to the prediction of critical flow rates. An extension of the static flashing inception correlation of Jones [16] and Alamgir and Lienhard [17] to flowing systems has allowed the determination of the location of flashing inception in nozzle flows with subcooled inlet conditions. It is shown that in all the experiments examined with subcooled inlet regardless of the degree of inlet subcooling, flashing inception invariably occurred very close to the throat. A correlation is given to predict flashing inception in both pipes and nozzles which matches all data available, but is lacking verification in intermediate nozzle geometries where turbulence may be important. A consequence of this behavior is that the critical mass flux may be correlated to the pressure difference between the nozzle inlet and flashing inception, through a single phase liquid discharge coefficient and an accurate prediction of the flashing inception pressure at the throat. Comparison with the available experiments indicate that the predicted mass fluxes are within 5 percent of the measurements

  19. Fluid Structure Interaction in a Cold Flow Test and Transient CFD Analysis of Out-of-Round Nozzles

    Science.gov (United States)

    Ruf, Joseph; Brown, Andrew; McDaniels, David; Wang, Ten-See

    2010-01-01

    This viewgraph presentation describes two nozzle fluid flow interactions. They include: 1) Cold flow nozzle tests with fluid-structure interaction at nozzle separated flow; and 2) CFD analysis for nozzle flow and side loads of nozzle extensions with various out-of-round cases.

  20. Flow Energy Piezoelectric Bimorph Nozzle Harvester

    Science.gov (United States)

    Sherrit, Stewart (Inventor); Walkemeyer, Phillip E. (Inventor); Hall, Jeffrey L. (Inventor); Lee, Hyeong Jae (Inventor); Colonius, Tim (Inventor); Tosi, Phillipe (Inventor); Kim, Namhyo (Inventor); Sun, Kai (Inventor); Corbett, Thomas Gary (Inventor); Arrazola, Alvaro Jose (Inventor)

    2016-01-01

    A flow energy harvesting device having a harvester pipe includes a flow inlet that receives flow from a primary pipe, a flow outlet that returns the flow into the primary pipe, and a flow diverter within the harvester pipe having an inlet section coupled to the flow inlet, a flow constriction section coupled to the inlet section and positioned at a midpoint of the harvester pipe and having a spline shape with a substantially reduced flow opening size at a constriction point along the spline shape, and an outlet section coupled to the constriction section. The harvester pipe may further include a piezoelectric structure extending from the inlet section through the constriction section and point such that the fluid flow past the constriction point results in oscillatory pressure amplitude inducing vibrations in the piezoelectric structure sufficient to cause a direct piezoelectric effect and to generate electrical power for harvesting.

  1. Calibration of nozzle for air mass flow measurement

    Science.gov (United States)

    Uher, Jan; Kanta, Lukáš

    2017-09-01

    The effort to make calibration measurement of mass flow through a nozzle was not satisfying. Traversing across the pipe radius with Pitot probe was done. The presence of overshoot behind the bend in the pipe was found. The overshoot led to an asymmetric velocity profile.

  2. Magnetogasdynamic Flow Acceleration in a Scramjet Nozzle

    National Research Council Canada - National Science Library

    Harrington, Brian

    2004-01-01

    .... The parameters of conductivity pattern and load factor are varied in both inviscid and viscous flow regimes with the intent of increasing axial force exerted on the flow through a scramjet accelerator...

  3. Vortex flow and cavitation in diesel injector nozzles

    Science.gov (United States)

    Andriotis, A.; Gavaises, M.; Arcoumanis, C.

    Flow visualization as well as three-dimensional cavitating flow simulations have been employed for characterizing the formation of cavitation inside transparent replicas of fuel injector valves used in low-speed two-stroke diesel engines. The designs tested have incorporated five-hole nozzles with cylindrical as well as tapered holes operating at different fixed needle lift positions. High-speed images have revealed the formation of an unsteady vapour structure upstream of the injection holes inside the nozzle volume, which is referred to as . Computation of the flow distribution and combination with three-dimensional reconstruction of the location of the strings inside the nozzle volume has revealed that strings are found at the core of recirculation zones; they originate either from pre-existing cavitation sites forming at sharp corners inside the nozzle where the pressure falls below the vapour pressure of the flowing liquid, or even from suction of outside air downstream of the hole exit. Processing of the acquired images has allowed estimation of the mean location and probability of appearance of the cavitating strings in the three-dimensional space as a function of needle lift, cavitation and Reynolds number. The frequency of appearance of the strings has been correlated with the Strouhal number of the vortices developing inside the sac volume; the latter has been found to be a function of needle lift and hole shape. The presence of strings has significantly affected the flow conditions at the nozzle exit, influencing the injected spray. The cavitation structures formed inside the injection holes are significantly altered by the presence of cavitation strings and are jointly responsible for up to 10% variation in the instantaneous fuel injection quantity. Extrapolation using model predictions for real-size injectors operating at realistic injection pressures indicates that cavitation strings are expected to appear within the time scales of typical injection

  4. Gas flows in radial micro-nozzles with pseudo-shocks

    Science.gov (United States)

    Kiselev, S. P.; Kiselev, V. P.; Zaikovskii, V. N.

    2017-12-01

    In the present paper, results of an experimental and numerical study of supersonic gas flows in radial micro-nozzles are reported. A distinguishing feature of such flows is the fact that two factors, the nozzle divergence and the wall friction force, exert a substantial influence on the flow structure. Under the action of the wall friction force, in the micro-nozzle there forms a pseudo-shock that separates the supersonic from subsonic flow region. The position of the pseudo-shock can be evaluated from the condition of flow blockage in the nozzle exit section. A detailed qualitative and quantitative analysis of gas flows in radial micro-nozzles is given. It is shown that the gas flow in a micro-nozzle is defined by the complicated structure of the boundary layer in the micro-nozzle, this structure being dependent on the width-to-radius ratio of the nozzle and its inlet-to-outlet pressure ratio.

  5. Three Dimensional Steady Subsonic Euler Flows in Bounded Nozzles

    OpenAIRE

    Chen, Chao; Xie, Chunjing

    2013-01-01

    In this paper, we study the existence and uniqueness of three dimensional steady Euler flows in rectangular nozzles when prescribing normal component of momentum at both the entrance and exit. If, in addition, the normal component of the voriticity and the variation of Bernoulli's function at the exit are both zero, then there exists a unique subsonic potential flow when the magnitude of the normal component of the momentum is less than a critical number. As the magnitude of the normal compon...

  6. Heat and fluid flow properties of circular impinging jet with a low nozzle to plate spacing. Improvement by nothched nozzle; Nozzle heibankan kyori ga chiisai baai no enkei shototsu funryu no ryudo dennetsu tokusei. Kirikaki nozzle ni yoru kaizen kojo

    Energy Technology Data Exchange (ETDEWEB)

    Shakouchih, T. [Mie University, Mie (Japan). Faculty of Engineering; Matsumoto, A.; Watanabe, A.

    2000-10-25

    It is well known that as decreasing the nozzle to plate spacing considerably the heat transfer coefficient of circular impinging jet, which impinges to the plate normally, increases remarkably. At that time, the flow resistance of nozzle-plate system also increases rapidly. In this study, in order to reduce the flow resistance and to enhance the heat transfer coefficient of the circular impinging jet with a considerably low nozzle to plate spacing, a special nozzle with notches is proposed, and considerable improvement of the flow and heat transfer properties are shown. The mechanism of enhancement of the heat transfer properties is also discussed. (author)

  7. Three-Dimensional Flow Behavior Inside the Submerged Entry Nozzle

    Science.gov (United States)

    Real-Ramirez, Cesar Augusto; Carvajal-Mariscal, Ignacio; Sanchez-Silva, Florencio; Cervantes-de-la-Torre, Francisco; Diaz-Montes, Jesus; Gonzalez-Trejo, Jesus

    2018-05-01

    According to various authors, the surface quality of steel depends on the dynamic conditions that occur within the continuous casting mold's upper region. The meniscus, found in that upper region, is where the solidification process begins. The liquid steel is distributed into the mold through a submerged entry nozzle (SEN). In this paper, the dynamic behavior inside the SEN is analyzed by means of physical experiments and numerical simulations. The particle imaging velocimetry technique was used to obtain the vector field in different planes and three-dimensional flow patterns inside the SEN volume. Moreover, large eddy simulation was performed, and the turbulence model results were used to understand the nonlinear flow pattern inside the SEN. Using scaled physical and numerical models, quasi-periodic behavior was observed due to the interaction of two three-dimensional vortices that move inside the SEN lower region located between the exit ports of the nozzle.

  8. Nozzle Flow with Vibrational Nonequilibrium. Ph.D. Thesis

    Science.gov (United States)

    Landry, John Gary

    1995-01-01

    Flow of nitrogen gas through a converging-diverging nozzle is simulated. The flow is modeled using the Navier-Stokes equations that have been modified for vibrational nonequilibrium. The energy equation is replaced by two equations. One equation accounts for energy effects due to the translational and rotational degrees of freedom, and the other accounts for the affects due to the vibrational degree of freedom. The energy equations are coupled by a relaxation time which measures the time required for the vibrational energy component to equilibrate with the translational and rotational energy components. An improved relaxation time is used in this thesis. The equations are solved numerically using the Steger-Warming flux vector splitting method and the Implicit MacCormack method. The results show that uniform flow is produced outside of the boundary layer. Nonequilibrium exists in both the converging and diverging nozzle sections. The boundary layer region is characterized by a marked increase in translational-rotational temperature. The vibrational temperature remains frozen downstream of the nozzle, except in the boundary layer.

  9. Experimental investigation of a two-phase nozzle flow

    International Nuclear Information System (INIS)

    Kedziur, F.; John, H.; Loeffel, R.; Reimann, J.

    1980-07-01

    Stationary two-phase flow experiments with a convergent nozzle are performed. The experimental results are appropriate to validate advanced computer codes, which are applied to the blowdown-phase of a loss-of-coolant accident (LOCA). The steam-water experiments present a broad variety of initial conditions: the pressure varies between 2 and 13 MPa, the void fraction between 0 (subcooled) and about 80%, a great number of critical as well as subcritical experiments with different flow pattern is investigated. Additional air-water experiments serve for the separation of phase transition effects. The transient acceleration of the fluid in the LOCA-case is simulated by a local acceleration in the experiment. The layout of the nozzle and the applied measurement technique allow for a separate testing of blowdown-relevant, physical models and the determination of empirical model parameters, respectively. The measured quantities are essentially the mass flow rate, quality, axial pressure and temperature profiles as well as axial and radial density/void profiles obtained by a γ-ray absorption device. Moreover, impedance probes and a pitot probe are used. Observed phenomena like a flow contraction, radial pressure and void profiles as well as the appearance of two chocking locations are described, because their examination is rather instructive about the refinement of a program. The experimental facilities as well as the data of 36 characteristic experiments are documented. (orig.) [de

  10. Analysis and design of optimized truncated scarfed nozzles subject to external flow effects

    Science.gov (United States)

    Shyne, Rickey J.; Keith, Theo G., Jr.

    1990-01-01

    Rao's method for computing optimum thrust nozzles is modified to study the effects of external flow on the performance of a class of exhaust nozzles. Members of this class are termed scarfed nozzles. These are two-dimensional, nonsymmetric nozzles with a flat lower wall. The lower wall (the cowl) is truncated in order to save weight. Results from a parametric investigation are presented to show the effects of the external flowfield on performance.

  11. INVESTIGATION OF FLOW BEHAVIOR IN MINIMUM QUANTITY LUBRICATION NOZZLE FOR END MILLING PROCESSES

    Directory of Open Access Journals (Sweden)

    M.S. Najiha

    2012-12-01

    Full Text Available Minimum quantity lubrication (MQL is a sustainable manufacturing technique that has replaced conventional flooded lubrication methods and dry machining. In the MQL technique, the lubricant is sprayed onto the friction surfaces through nozzles through small pneumatically-operated pumps. This paper presents an investigation into the flow behavior of the lubricant and air mixture under certain pressures at the tip of a nozzle specially designed for MQL. The nozzle used is an MQL stainless steel nozzle, 6.35 mm in diameter. Computational fluid dynamics is used to determine the flow pattern at the tip of the nozzle where the lubricant and compressed air are mixed to form a mist. The lubricant volume flow is approximately 0.08 ml/cycle of the pump. A transient, pressure-based, three-dimensional analysis is performed with a viscous, realizable k-ε model. The results are obtained in the form of vector plots and flow fields. The flow mixing at the tip of the nozzle is wholly shown through the flow fields and vector plots. This study provides an insight into the flow distribution at the tip of the nozzle for a certain pressure to aid modifications in the design of the nozzle for future MQL studies. It attainable aids to determine the correct pressure for the air jet at the nozzle tip.

  12. EXAMPLE OF FLOW MODELLING CHARACTERISTICS IN DIESEL ENGINE NOZZLE

    Directory of Open Access Journals (Sweden)

    Dušan KOLARIČ

    2016-03-01

    Full Text Available Modern transport is still based on vehicles powered by internal combustion engines. Due to stricter ecological requirements, the designers of engines are continually challenged to develop more environmentally friendly engines with the same power and performance. Unfortunately, there are not any significant novelties and innovations available at present which could significantly change the current direction of the development of this type of propulsion machines. That is why the existing ones should be continually developed and improved or optimized their performance. By optimizing, we tend to minimize fuel consumption and lower exhaust emissions in order to meet the norms defined by standards (i.e. Euro standards. Those propulsion engines are actually developed to such extent that our current thinking will not be able to change their basic functionality, but possible opportunities for improvement, especially the improvement of individual components, could be introduced. The latter is possible by computational fluid dynamics (CFD which can relatively quickly and inexpensively produce calculations prior to prototyping and implementation of accurate measurements on the prototype. This is especially useful in early stages of development or at optimization of dimensional small parts of the object where the physical execution of measurements is impossible or very difficult. With advances of computational fluid dynamics, the studies on the nozzles and outlet channel injectors have been relieved. Recently, the observation and better understanding of the flow in nozzles at large pressure and high velocity is recently being possible. This is very important because the injection process, especially the dispersion of jet fuel, is crucial for the combustion process in the cylinder and consequently for the composition of exhaust gases. And finally, the chemical composition of the fuel has a strong impact on the formation of dangerous emissions, too. The

  13. Two-phase flow in a diverging nozzle

    International Nuclear Information System (INIS)

    Wadle, M.

    1986-05-01

    Stationary two-phase flow experiments were performed with steam-water and air-water mixtures in a well-instrumented horizontal diverging nozzle. The test section consisted of a constant diameter tube, the friction-section, followed by an expansion, the diffusor, which has a tanh-contour and finally another constant diameter tube. The diameter ratio sigma=D1/D2 is 16/80. For the steam-water experiments the flow parameters were: 0 2 and for air-water mixtures (0 2 ). The initial conditions were varied to achieve subcritical and critical mass flow rates. A new model for the pressure recovery in an abrupt expansion is presented. It is based on the superficial velocity concept and agrees well with the steam-water and the water-air experimental data as well as with the experiments of other authors. The experiments were also calculated with the two-phase code DUESE. The Drift-Flux models in this code as well as the constitutive correlations and their empirical constants could be tested. It is shown, that a 1D Drift-Flux code can handle the highly transient flow in the diffusor if the proper drift model is used. In a 1D simulation it is only necessary that the computational flow area is expanded to its full width within an axial length which is equivalent to the real contour. (orig./GL) [de

  14. Three dimensional steady subsonic Euler flows in bounded nozzles

    Science.gov (United States)

    Chen, Chao; Xie, Chunjing

    The existence and uniqueness of three dimensional steady subsonic Euler flows in rectangular nozzles were obtained when prescribing normal component of momentum at both the entrance and exit. If, in addition, the normal component of the voriticity and the variation of Bernoulli's function at the entrance are both zero, then there exists a unique subsonic potential flow when the magnitude of the normal component of the momentum is less than a critical number. As the magnitude of the normal component of the momentum approaches the critical number, the associated flows converge to a subsonic-sonic flow. Furthermore, when the normal component of vorticity and the variation of Bernoulli function are both small, the existence and uniqueness of subsonic Euler flows with non-zero vorticity are established. The proof of these results is based on a new formulation for the Euler system, a priori estimate for nonlinear elliptic equations with nonlinear boundary conditions, detailed study for a linear div-curl system, and delicate estimate for the transport equations.

  15. The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow

    KAUST Repository

    Elbaz, Ayman M.; Zayed, M.F.; Samy, M.; Roberts, William L.; Mansour, Mohy S.

    2015-01-01

    The stability limits, the stabilization mechanism, and the flow field structure of highly stabilized partially premixed methane flames in a concentric flow conical nozzle burner with air co-flow have been investigated and presented in this work

  16. Interior flow and near-nozzle spray development in a marine-engine diesel fuel injector

    Science.gov (United States)

    Hult, J.; Simmank, P.; Matlok, S.; Mayer, S.; Falgout, Z.; Linne, M.

    2016-04-01

    A consolidated effort at optically characterising flow patterns, in-nozzle cavitation, and near-nozzle jet structure of a marine diesel fuel injector is presented. A combination of several optical techniques was employed to fully transparent injector models, compound metal-glass and full metal injectors. They were all based on a common real-scale dual nozzle hole geometry for a marine two-stroke diesel engine. In a stationary flow rig, flow velocities in the sac-volume and nozzle holes were measured using PIV, and in-nozzle cavitation visualized using high-resolution shadowgraphs. The effect of varying cavitation number was studied and results compared to CFD predictions. In-nozzle cavitation and near-nozzle jet structure during transient operation were visualized simultaneously, using high-speed imaging in an atmospheric pressure spray rig. Near-nozzle spray formation was investigated using ballistic imaging. Finally, the injector geometry was tested on a full-scale marine diesel engine, where the dynamics of near-nozzle jet development was visualized using high-speed shadowgraphy. The range of studies focused on a single common geometry allows a comprehensive survey of phenomena ranging from first inception of cavitation under well-controlled flow conditions to fuel jet structure at real engine conditions.

  17. Nature of convection-stabilized dc arcs in dual-flow nozzle geometry

    International Nuclear Information System (INIS)

    Serbetci, I.; Nagamatsu, H.T.

    1990-01-01

    In this paper, an experimental investigation of the steady-state low-current air arcs in a dual-flow nozzle system is presented. First, the cold flow with no arc as determined for various nozzle geometries, i.e., two- and three-dimensional and orifice nozzles, and nozzle pressure ratios. Supersonic flow separation and oblique and detached shock waves were observed in the flow field. Using a finite-element computer program, the Mach number contours were determined in the flow field for various nozzle-gap spacings and pressure ratios. In addition, the dc arc voltage and current measurements were made for an electrode gap spacing of ∼ 5.5 cm and current levels of I ∼ 25, 50, and 100 A for the three nozzle geometries. The arc voltage and arc power increased rapidly as the flow speed increased from zero to sonic velocity at the nozzle throat. The shock waves in the converging-diverging nozzles resulted in a decrease in the overall resistance by about 15 percent

  18. INVESTIGATION OF FLOW BEHAVIOR IN MINIMUM QUANTITY LUBRICATION NOZZLE FOR END MILLING PROCESSES

    OpenAIRE

    M.S. Najiha; M.M.Rahman; A.R. Yusoff; K. Kadirgama

    2012-01-01

    Minimum quantity lubrication (MQL) is a sustainable manufacturing technique that has replaced conventional flooded lubrication methods and dry machining. In the MQL technique, the lubricant is sprayed onto the friction surfaces through nozzles through small pneumatically-operated pumps. This paper presents an investigation into the flow behavior of the lubricant and air mixture under certain pressures at the tip of a nozzle specially designed for MQL. The nozzle used is an MQL stainless steel...

  19. Laminar and turbulent nozzle-jet flows and their acoustic near-field

    International Nuclear Information System (INIS)

    Bühler, Stefan; Obrist, Dominik; Kleiser, Leonhard

    2014-01-01

    We investigate numerically the effects of nozzle-exit flow conditions on the jet-flow development and the near-field sound at a diameter-based Reynolds number of Re D = 18 100 and Mach number Ma = 0.9. Our computational setup features the inclusion of a cylindrical nozzle which allows to establish a physical nozzle-exit flow and therefore well-defined initial jet-flow conditions. Within the nozzle, the flow is modeled by a potential flow core and a laminar, transitional, or developing turbulent boundary layer. The goal is to document and to compare the effects of the different jet inflows on the jet flow development and the sound radiation. For laminar and transitional boundary layers, transition to turbulence in the jet shear layer is governed by the development of Kelvin-Helmholtz instabilities. With the turbulent nozzle boundary layer, the jet flow development is characterized by a rapid changeover to a turbulent free shear layer within about one nozzle diameter. Sound pressure levels are strongly enhanced for laminar and transitional exit conditions compared to the turbulent case. However, a frequency and frequency-wavenumber analysis of the near-field pressure indicates that the dominant sound radiation characteristics remain largely unaffected. By applying a recently developed scaling procedure, we obtain a close match of the scaled near-field sound spectra for all nozzle-exit turbulence levels and also a reasonable agreement with experimental far-field data

  20. Numerical Analysis of Pelton Nozzle Jet Flow Behavior Considering Elbow Pipe

    Science.gov (United States)

    Chongji, Zeng; Yexiang, Xiao; Wei, Xu; Tao, Wu; Jin, Zhang; Zhengwei, Wang; Yongyao, Luo

    2016-11-01

    In Pelton turbine, the dispersion of cylindrical jet have a great influence on the energy interaction of jet and buckets. This paper simulated the internal flow of nozzle and the downstream free jet flow at 3 different needle strokes. The nozzle model consists of the elbow pipe and the needle rod which supported by 4 ribs. Homogenous model and SST k-ω model were adopted to simulate the unsteady two-phase jet flow. The development of free flow, including a contraction process followed by an expansion process, was analysed detailed as well as the influence of the nozzle geometry on the jet flow pattern. The increase of nozzle opening results in a more dispersion jet, which means a higher hydraulic loss. Upstream bend and ribs induce the secondary flow in the jet and decrease the jet concentration.

  1. Numerical analysis of choked converging nozzle flows with surface ...

    Indian Academy of Sciences (India)

    Choked converging nozzle flow and heat transfer characteristics are numerically investigated by means of a recent computational model that integrates the axisymmetric continuity, state, momentum and energy equations. To predict the combined effects of nozzle geometry, friction and heat transfer rates, analyses are ...

  2. Pengaruh Variasi Lip Thickness pada Nozzle Terpancung terhadap Karakteristik Api Pembakaran Difusi Concentric Jet Flow

    Directory of Open Access Journals (Sweden)

    Elka Faizal

    2016-05-01

    Full Text Available Nozzle shape greatly influence turbulence between the fuel, air and formation of flow recirculation zone to produce a homogeneous mixing and get a near-perfect combustion. The recirculation zone is area that caused by flow rate breakdown, causing vortex and backflow around the end of nozzle. This backflow that hold up while lowering the flame so the flow rate of fuel and air mixture maintained lower or equal with flame speed. This study used variation of lip thickness of truncated nozzle 0, 4, 8, 12, and 16 mm.To obtain flame stability, fuel velocity and air velocity were variated. Thermocouples were used to measure flame temperature and its distribution. The results showed that stability of concentric jet diffusion flame flow increased with narrow lip thickness on a truncated nozzle. The wider stability area obtained in 4 mm lip thickness. In addition, temperature on diffusion flames concentric jet flow also more evenly distributed evenly with size of the nozzle lip thickness. The highest temperature and temperature distribution in the horizontal direction were occured in in the nozzle with lip thickness of 0 mm. A shadowgrapgh visualization was also used to identify phenomena of the nozzle exit flow.

  3. Three Dimensional Viscous Flow Field in an Axial Flow Turbine Nozzle Passage

    Science.gov (United States)

    Ristic, D.; Lakshminarayana, B.

    1997-01-01

    The objective of this investigation is experimental and computational study of three dimensional viscous flow field in the nozzle passage of an axial flow turbine stage. The nozzle passage flow field has been measured using a two sensor hot-wire probe at various axial and radial stations. In addition, two component LDV measurements at one axial station (x/c(sum m) = 0.56) were performed to measure the velocity field. Static pressure measurements and flow visualization, using a fluorescent oil technique, were also performed to obtain the location of transition and the endwall limiting streamlines. A three dimensional boundary layer code, with a simple intermittency transition model, was used to predict the viscous layers along the blade and endwall surfaces. The boundary layers on the blade surface were found to be very thin and mostly laminar, except on the suction surface downstream of 70% axial chord. Strong radial pressure gradient, especially close to the suction surface, induces strong cross flow components in the trailing edge regions of the blade. On the end-walls the boundary layers were much thicker, especially near the suction corner of the casing surface, caused by secondary flow. The secondary flow region near the suction-casing surface corner indicates the presence of the passage vortex detached from the blade surface. The corner vortex is found to be very weak. The presence of a closely spaced rotor downstream (20% of the nozzle vane chord) introduces unsteadiness in the blade passage. The measured instantaneous velocity signal was filtered using FFT square window to remove the periodic unsteadiness introduced by the downstream rotor and fans. The filtering decreased the free stream turbulence level from 2.1% to 0.9% but had no influence on the computed turbulence length scale. The computation of the three dimensional boundary layers is found to be accurate on the nozzle passage blade surfaces, away from the end-walls and the secondary flow region. On

  4. Nozzle flow and atomization characteristics of ethanol blended biodiesel fuel

    Energy Technology Data Exchange (ETDEWEB)

    Park, Su Han; Suh, Hyun Kyu; Lee, Chang Sik [Department of Mechanical Engineering, Graduate School of Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791 (Korea)

    2010-01-15

    This study was conducted to investigate the injection and atomization characteristics of biodiesel-ethanol blended fuel. The injection performance of biodiesel-ethanol blended fuel was analyzed from the injection rate characteristics using the injection rate measuring system, and the effective injection velocity and effective spray diameter using the nozzle flow model. Moreover, the atomization characteristics, such as local and overall SMD distributions, overall axial velocity and droplet arrival time were analyzed and compared with these from diesel and biodiesel fuels to obtain the atomization characteristics of biodiesel-ethanol blended fuel. It was revealed that ethanol fuel affects the decrease of the peak injection rate and the shortening of the injection delay due to the decrease of fuel properties, such as fuel density and dynamic viscosity. In addition, the ethanol addition improved the atomization performance of biodiesel fuel, because the ethanol blended fuel has a low kinematic viscosity and surface tension, then that has more active interaction with the ambient gas, compared to BD100. (author)

  5. Two-way coupled simulation of a flow laden with metallic particulates in overexpanded TIC nozzle

    International Nuclear Information System (INIS)

    Moshfegh, Abouzar; Shams, Mehrzad; Ebrahimi, Reza; Farnia, Mohammad Ali

    2009-01-01

    A simulation of non-reacting dilute gas-solid flow in a truncated ideal contour nozzle with consideration of external stream interactions is performed. The Eulerian-Lagrangian approach involving a two-way momentum and thermal coupling between gas and particles phases is also adopted. Of interests are to investigate the effects of particles diameter and mass flow fraction on the flow pattern, Mach number, pressure and temperature contours and their distributions along the nozzle centerline and wall. The main goal is to determine the separation point quantitatively when the particles characteristics change. Particles sample trajectories are illustrated throughout the flow field and a qualitative discussion on the way that physical properties of the nozzle exit flow and particles trajectories oscillate is prepared. The existence of solid particulates delays the separation prominently in the cases studied. The bigger particles and the higher particles mass flow fractions respectively advance and delay the separation occurrence. The particles trajectories oscillate when they expose to the crisscrossing (or diamond-shape) shock waves generated outside the nozzle to approach the exit jet conditions to the ambient. The simulation code is validated and verified, respectively, against a one-phase 2D convergent-divergent nozzle flow and a two-phase Jet Propulsion Laboratory nozzle flow, and acceptable agreements are achieved.

  6. On nitrogen condensation in hypersonic nozzle flows: Numerical method and parametric study

    KAUST Repository

    Lin, Longyuan; Cheng, Wan; Luo, Xisheng; Qin, Fenghua

    2013-01-01

    A numerical method for calculating two-dimensional planar and axisymmetric hypersonic nozzle flows with nitrogen condensation is developed. The classical nucleation theory with an empirical correction function and the modified Gyarmathy model

  7. Laboratory Observation of a Plasma-Flow-State Transition from Diverging to Stretching a Magnetic Nozzle.

    Science.gov (United States)

    Takahashi, Kazunori; Ando, Akira

    2017-06-02

    An axial magnetic field induced by a plasma flow in a divergent magnetic nozzle is measured when injecting the plasma flow from a radio frequency (rf) plasma source located upstream of the nozzle. The source is operated with a pulsed rf power of 5 kW, and the high density plasma flow is sustained only for the initial ∼100  μsec of the discharge. The measurement shows a decrease in the axial magnetic field near the source exit, whereas an increase in the field is detected at the downstream side of the magnetic nozzle. These results demonstrate a spatial transition of the plasma-flow state from diverging to stretching the magnetic nozzle, where the importance of both the Alfvén and ion Mach numbers is shown.

  8. A computational investigation on the influence of the use of elliptical orifices on the inner nozzle flow and cavitation development in diesel injector nozzles

    International Nuclear Information System (INIS)

    Molina, S.; Salvador, F.J.; Carreres, M.; Jaramillo, D.

    2014-01-01

    Highlights: • The influence of elliptical orifices on the inner nozzle flow is compared. • Five nozzles with different elliptical and circular orifices are simulated. • Differences in the flow coefficients and cavitation morphology are observed. • Horizontal axis orifices are ease to cavitate, with a higher discharge coefficient. • A better mixing process quality is expected for the horizontal major axis nozzles. - Abstract: In this paper a computational study was carried out in order to investigate the influence of the use of elliptical orifices on the inner nozzle flow and cavitation development. With this aim, a large number of injection conditions have been simulated and analysed for 5 different nozzles: four nozzles with different elliptical orifices and one standard nozzle with circular orifices. The four elliptical nozzles differ from each other in the orientation of the major axis (vertical or horizontal) and in the eccentricity value, but keeping the same outlet section in all cases. The comparison has been made in terms of mass flow, momentum flux and other important non-dimensional parameters which help to describe the behaviour of the inner nozzle flow: discharge coefficient (C d ), area coefficient (C a ) and velocity coefficient (C v ). The simulations have been done with a code able to simulate the flow under either cavitating or non-cavitating conditions. This code has been previously validated using experimental measurements over the standard nozzle with circular orifices. The main results of the investigation have shown how the different geometries modify the critical cavitation conditions as well as the discharge coefficient and the effective velocity. In particular, elliptical geometries with vertically oriented major axis are less prone to cavitate and have a lower discharge coefficient, whereas elliptical geometries with horizontally oriented major axis are more prone to cavitate and show a higher discharge coefficient

  9. BWR fuel assembly bottom nozzle with one-way coolant flow valve

    International Nuclear Information System (INIS)

    Taleyarkhan, R.P.

    1987-01-01

    In a nuclear reactor having a flow of coolant/moderator fluid therein, at least one fuel assembly installed in the fluid flow, the fuel assembly is described comprising in combination: a bundle of elongated fuel rods disposed in side-by-side relationship so as to form an array of spaced fuel rods; an outer tubular flow channel surrounding the fuel rods so as to direct the flow of coolant/moderator fluid along the fuel rods; bottom and top nozzles mounted at opposite ends of the flow channel and having an inlet and outlet respectively for allowing entry and exit of the flow of coolant/moderator fluid into and from the flow channel and along the fuel rods therein; and a coolant flow direction control device operatively disposed in the bottom nozzle so as to open the inlet thereof to the flow of coolant/moderator fluid in an inflow direction into the flow channel through the bottom nozzle inlet but close the inlet to the flow of coolant/moderator fluid from the flow channel through the bottom nozzle inlet upon reversal of coolant/moderator fluid flow from the inflow direction

  10. Study for discharge coefficient of flow nozzles. Prediction by using numerical simulation

    International Nuclear Information System (INIS)

    Ikeda, Hiroshi; Sakai, Norio; Yamamoto, Yasushi; Arai, Kenji; Matsumoto, Masaaki

    2008-01-01

    In nuclear plant, as water feeding into reactor have much effect on thermal power of plant, it is important to measure accurately the flow rate of water. Flow nozzle is on of typical differential pressure type flow meters and the discharge coefficient is used to calculate the flow rate. This coefficient is given by actual experiment and theory. We studied the theoretical assumption of the discharge coefficient curve using numerical simulation and evaluated the effect of flow nozzle configuration on the coefficient numerically and experimentally. As the result, numerical simulation can predict the discharge coefficient of theoretical curve within 0.3%. And we found that the throat length and throat tapping location of flow nozzle have much effect on the coefficient. (author)

  11. The influence of cavitation on the flow characteristics of liquid nitrogen through spray nozzles: A CFD study

    Science.gov (United States)

    Xue, Rong; Ruan, Yixiao; Liu, Xiufang; Cao, Feng; Hou, Yu

    2017-09-01

    Spray cooling with cryogen could achieve lower temperature level than refrigerant spray. The internal flow conditions within spray nozzles have crucial impacts on the mass flow rate, particle size, spray angle and spray penetration, thereby influencing the cooling performance. In this paper, CFD simulations based on mixture model are performed to study the cavitating flow of liquid nitrogen in spray nozzles. The cavitation model is verified using the experimental results of liquid nitrogen flow over hydrofoil. The numerical models of spray nozzle are validated against the experimental data of the mass flow rate of liquid nitrogen flow through different types of nozzles including the pressure swirl nozzle and the simple convergent nozzle. The numerical studies are performed under a wide range of pressure difference and inflow temperature, and the vapor volume fraction distribution, outlet vapor quality, mass flow rate and discharge coefficient are obtained. The results show that the outlet diameter, the pressure difference, and the inflow temperature significantly influence the mass flow rate of spray nozzles. The increase of the inflow temperature leads to higher saturation pressure, higher cavitation intensity, and more vapor at nozzle outlet, which can significantly reduce mass flow rate. While the discharge coefficient is mainly determined by the inflow temperature and has little dependence on the pressure difference and outlet diameter. Based on the numerical results, correlations of discharge coefficient are proposed for pressure swirl nozzle and simple convergent nozzles, respectively, and the deviation is less than 20% for 93% of data.

  12. Numerical Simulation of Reactive Flows in Overexpanded Supersonic Nozzle with Film Cooling

    Directory of Open Access Journals (Sweden)

    Mohamed Sellam

    2015-01-01

    Full Text Available Reignition phenomena occurring in a supersonic nozzle flow may present a crucial safety issue for rocket propulsion systems. These phenomena concern mainly rocket engines which use H2 gas (GH2 in the film cooling device, particularly when the nozzle operates under over expanded flow conditions at sea level or at low altitudes. Consequently, the induced wall thermal loads can lead to the nozzle geometry alteration, which in turn, leads to the appearance of strong side loads that may be detrimental to the rocket engine structural integrity. It is therefore necessary to understand both aerodynamic and chemical mechanisms that are at the origin of these processes. This paper is a numerical contribution which reports results from CFD analysis carried out for supersonic reactive flows in a planar nozzle cooled with GH2 film. Like the experimental observations, CFD simulations showed their ability to highlight these phenomena for the same nozzle flow conditions. Induced thermal load are also analyzed in terms of cooling efficiency and the results already give an idea on their magnitude. It was also shown that slightly increasing the film injection pressure can avoid the reignition phenomena by moving the separation shock towards the nozzle exit section.

  13. Nuclear research reactor IEA-R1 heat exchanger inlet nozzle flow - a preliminary study

    International Nuclear Information System (INIS)

    Angelo, Gabriel; Andrade, Delvonei Alves de; Fainer, Gerson; Angelo, Edvaldo

    2009-01-01

    As a computational fluid mechanics training task, a preliminary model was developed. ANSYS-CFX R code was used in order to study the flow at the inlet nozzle of the heat exchanger of the primary circuit of the nuclear research reactor IEA-R1. The geometry of the inlet nozzle is basically compounded by a cylinder and two radial rings which are welded on the shell. When doing so there is an offset between the holes through the shell and the inlet nozzle. Since it is not standardized by TEMA, the inlet nozzle was chosen for a preliminary study of the flow. Results for the proposed model are presented and discussed. (author)

  14. Characterization of the cavitating flow in converging-diverging nozzle based on experimental investigations

    Directory of Open Access Journals (Sweden)

    Rudolf Pavel

    2014-03-01

    Full Text Available Cavitation phenomena occuring in converging-diverging nozzle (Venturi tube are described in the paper. A closed test circuit with possibility to control both flow rate and static pressure level were used. Loss coefficient was evaluated for different sigma numbers resulting in full „static“ characterization of the nozzle. Visualizations of the cavitation pattern development were acquired and matched with evolution of the loss coefficient. Three cavitation regimes are described: partial cavitation, fully developed cavitation, supercavitation.

  15. Experimental study and theoretical modelling of two-phase flow in a converging diverging nozzle

    International Nuclear Information System (INIS)

    Selmer-Olsen, Stale

    1991-01-01

    A theoretical and experimental study of high quality two-phase flows in converging-diverging nozzles is presented. The main objectives are the prediction of critical (choked) flow rates and the evolution of characteristic parameters towards the nozzle outlet. First, a thorough analysis of available models shows the importance of a correct modelling of the mechanical and thermal interactions between the gas and liquid phases. As a second step, a purely dispersed flow model is considered. The solution algorithm which is utilized describes accurately the critical (choked) flow conditions as well as the topology of the solutions. The dispersed flow model accounts for effects on the gas flow rate of the upstream and the downstream pressures, the liquid flow rate and the nozzle geometry. The pressure profile along the nozzle and the location of the critical cross-section are also well predicted. The flow is shown to switch from critical to sub-critical when the liquid flow rate is increased, all other control parameters at the inlet and the outlet maintained. This new finding is interpreted as a result of the possible location of the critical cross-section anywhere in the diverging part of the nozzle. Moreover, the experiments show that the critical (choked) gas flow rate depends on the inlet configuration of gas/liquid. In the third step, a careful analysis of the data is used as a basis for proposing a new dispersed-annular flow model. This model accounts for the liquid flowing both as a liquid film and as entrained droplets in the core, non-developed flow is accounted for as well as flow separation in the diffuser. Finally, advanced local measuring techniques of pressure, film thickness and film velocity have been developed in the course of the work. In particular film thickness measurements allowed the development of the flow structure to be understood. (author) [fr

  16. An investigation of transient nature of the cavitating flow in injector nozzles

    International Nuclear Information System (INIS)

    He, Zhixia; Zhong, Wenjun; Wang, Qian; Jiang, Zhaochen; Fu, Yanan

    2013-01-01

    In diesel engines, the cavitating flow in nozzles greatly affects the fuel atomization characteristics and then the subsequent combustion and exhaust emissions. In this paper, with the needle lift curve on the basis of injection rate experimental data, a moving mesh generation strategy was applied for 3D simulation of the nozzle cavitating flow. Based on the third-generation synchrotrons of Shanghai Synchrotron Radiation facility (SSRF), a high-precision three-dimension structure of testing nozzle with detailed internal geometry information was obtained using X-ray radiography for a more accurate simulation. A flow visualization experiment system with a transparent scaled-up vertical multi-hole injector nozzle tip was setup. The experimental data was obtained to make a comparison to validate the calculated results and good qualitative agreement was shown between them. Afterward, the effects of needle movement on development of the cavitating flow and flow characteristics parameters were investigated. Finally, the influence of fuel temperature on development of the cavitating flow was also studied. Research of the flow characteristics for the diesel and biodiesel revealed that the flow characteristics of the biodiesel with a temperature rise of between 50 K and 60 K in injector nozzles will be similar to those of the diesel fuel. -- Highlights: ► The detailed geometry information was obtained using X-ray radiography. ► A visualization experiment system was setup for validating the numerical models. ► The detailed cavitating flow in nozzles can be gotten with a moving mesh. ► The flow characteristics between the diesel and biodiesel fuel are investigated

  17. Fuel density effect on near nozzle flow field in small laminar coflow diffusion flames

    KAUST Repository

    Xiong, Yuan

    2015-01-01

    Flow characteristics in small coflow diffusion flames were investigated with a particular focus on the near-nozzle region and on the buoyancy force exerted on fuels with densities lighter and heavier than air (methane, ethylene, propane, and n-butane). The flow-fields were visualized through the trajectories of seed particles. The particle image velocimetry technique was also adopted for quantitative velocity field measurements. The results showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle, emphasizing the importance of the relative density of the fuel to that of the air on the flow-field. Nozzle heating influenced the near-nozzle flow-field particularly among lighter fuels (methane and ethylene). Numerical simulations were also conducted, focusing specifically on the effect of specifying inlet boundary conditions for fuel. The results showed that a fuel inlet boundary with a fully developed velocity profile for cases with long tubes should be specified inside the fuel tube to permit satisfactory prediction of the flow-field. The calculated temperature fields also indicated the importance of the selection of the location of the inlet boundary, especially in testing various combustion models that include soot in small coflow diffusion flames. © 2014 The Combustion Institute.

  18. Cold Flow Determination of the Internal Flow Environment Around the Submerged TVC Nozzle for the Space Shuttle SRM

    Science.gov (United States)

    Whitesides, R. H.; Ghosh, A.; Jenkins, S. L.; Bacchus, D. L.

    1989-01-01

    A series of subscale cold flow tests was performed to quantify the gas flow characteristics at the aft end of the Space Shuttle Solid Rocket Motor. This information was used to support the analyses of the redesigned nozzle/case joint. A portion of the thermal loads at the joint are due to the circumferential velocities and pressure gradients caused primarily by the gimbaling of the submerged nose TVC nozzle. When the nozzle centerline is vectored with respect to the motor centerline, asymmetries are set up in the flow field under the submerged nozzle and immediately adjacent to the nozzle/case joint. Specific program objectives included: determination of the effects of nozzle gimbal angle and propellant geometry on the circumferential flow field; measurement of the static pressure and gas velocities in the vicinity of the nozzle/case joint; use of scaling laws to apply the subscale cold flow data to the full scale SRM; and generation of data for use in validation of 3-D computational fluid dynamic, CFD, models of the SRM flow field. These tests were conducted in the NASA Marshall Space Flight Center Airflow Facility with a 7.5 percent scale model of the aft segment of the SRM. Static and dynamic pressures were measured in the model to quantify the flow field. Oil flow data was also acquired to obtain qualitative visual descriptions of the flow field. Nozzle gimbal angles of 0, 3.5, and 7 deg were used with propellant grain configurations corresponding to motor burn times of 0, 9, 19, and 114 seconds. This experimental program was successful in generating velocity and pressure gradient data for the flow field around the submerged nose nozzle of the Space Shuttle SRM at various burn times and gimbal angles. The nature of the flow field adjacent to the nozzle/case joint was determined with oil droplet streaks, and the velocity and pressure gradients were quantified with pitot probes and wall static pressure measurements. The data was applied to the full scale SRM thru

  19. State-to-state modeling of non-equilibrium air nozzle flows

    Science.gov (United States)

    Nagnibeda, E.; Papina, K.; Kunova, O.

    2018-05-01

    One-dimensional non-equilibrium air flows in nozzles are studied on the basis of the state-to-state description of vibrational-chemical kinetics. Five-component mixture N2/O2/NO/N/O is considered taking into account Zeldovich exchange reactions of NO formation, dissociation, recombination and vibrational energy transitions. The equations for vibrational and chem-ical kinetics in a flow are coupled to the conservation equations of momentum and total energy and solved numerically for different conditions in a nozzle throat. The vibrational distributions of nitrogen and oxygen molecules, number densities of species as well as the gas temperature and flow velocity along a nozzle axis are analysed using the detailed state-to-state flow description and in the frame of the simplified one-temperature thermal equilibrium kinetic model. The comparison of the results showed the influence of non-equilibrium kinetics on macroscopic nozzle flow parameters. In the state-to-state approach, non-Boltzmann vibrational dis-tributions of N2 and O2 molecules with a plateau part at intermediate levels are found. The results are found with the use of the complete and simplified schemes of reactions and the impact of exchange reactions, dissociation and recombination on variation of vibrational level populations, mixture composition, gas velocity and temperature along a nozzle axis is shown.

  20. Vanishing Viscosity Approach to the Compressible Euler Equations for Transonic Nozzle and Spherically Symmetric Flows

    Science.gov (United States)

    Chen, Gui-Qiang G.; Schrecker, Matthew R. I.

    2018-04-01

    We are concerned with globally defined entropy solutions to the Euler equations for compressible fluid flows in transonic nozzles with general cross-sectional areas. Such nozzles include the de Laval nozzles and other more general nozzles whose cross-sectional area functions are allowed at the nozzle ends to be either zero (closed ends) or infinity (unbounded ends). To achieve this, in this paper, we develop a vanishing viscosity method to construct globally defined approximate solutions and then establish essential uniform estimates in weighted L p norms for the whole range of physical adiabatic exponents γ\\in (1, ∞) , so that the viscosity approximate solutions satisfy the general L p compensated compactness framework. The viscosity method is designed to incorporate artificial viscosity terms with the natural Dirichlet boundary conditions to ensure the uniform estimates. Then such estimates lead to both the convergence of the approximate solutions and the existence theory of globally defined finite-energy entropy solutions to the Euler equations for transonic flows that may have different end-states in the class of nozzles with general cross-sectional areas for all γ\\in (1, ∞) . The approach and techniques developed here apply to other problems with similar difficulties. In particular, we successfully apply them to construct globally defined spherically symmetric entropy solutions to the Euler equations for all γ\\in (1, ∞).

  1. On nitrogen condensation in hypersonic nozzle flows: Numerical method and parametric study

    KAUST Repository

    Lin, Longyuan

    2013-12-17

    A numerical method for calculating two-dimensional planar and axisymmetric hypersonic nozzle flows with nitrogen condensation is developed. The classical nucleation theory with an empirical correction function and the modified Gyarmathy model are used to describe the nucleation rate and the droplet growth, respectively. The conservation of the liquid phase is described by a finite number of moments of the size distribution function. The moment equations are then combined with the Euler equations and are solved by the finite-volume method. The numerical method is first validated by comparing its prediction with experimental results from the literature. The effects of nitrogen condensation on hypersonic nozzle flows are then numerically examined. The parameters at the nozzle exit under the conditions of condensation and no-condensation are evaluated. For the condensation case, the static pressure, the static temperature, and the amount of condensed fluid at the nozzle exit decrease with the increase of the total temperature. Compared with the no-condensation case, both the static pressure and temperature at the nozzle exit increase, and the Mach number decreases due to the nitrogen condensation. It is also indicated that preheating the nitrogen gas is necessary to avoid the nitrogen condensation even for a hypersonic nozzle with a Mach number of 5 operating at room temperatures. © 2013 Springer-Verlag Berlin Heidelberg.

  2. Fluorescence Imaging of Rotational and Vibrational Temperature in a Shock Tunnel Nozzle Flow

    Science.gov (United States)

    Palma, Philip C.; Danehy, Paul M.; Houwing, A. F. P.

    2003-01-01

    Two-dimensional rotational and vibrational temperature measurements were made at the nozzle exit of a free-piston shock tunnel using planar laser-induced fluorescence. The Mach 7 flow consisted predominantly of nitrogen with a trace quantity of nitric oxide. Nitric oxide was employed as the probe species and was excited at 225 nm. Nonuniformities in the distribution of nitric oxide in the test gas were observed and were concluded to be due to contamination of the test gas by driver gas or cold test gas.The nozzle-exit rotational temperature was measured and is in reasonable agreement with computational modeling. Nonlinearities in the detection system were responsible for systematic errors in the measurements. The vibrational temperature was measured to be constant with distance from the nozzle exit, indicating it had frozen during the nozzle expansion.

  3. Investigation of the cavitating flow in injector nozzles for diesel and biodiesel

    Science.gov (United States)

    Zhong, Wenjun; He, Zhixia; Wang, Qian; Jiang, Zhaochen; Fu, Yanan

    2013-07-01

    In diesel engines, the cavitating flow in nozzles greatly affects the fuel atomization characteristics and then the subsequent combustion and exhaust emissions. At present the biodiesel is a kind of prospective alternative fuel in diesel engines, the flow characteristics for the biodiesel fuel need to be investigated. In this paper, based on the third-generation synchrotrons of Shanghai Synchrotron Radiation facility (SSRF), a high-precision three-dimension structure of testing nozzle with detailed internal geometry information was obtained using X-ray radiography for a more accurate physical model. A flow visualization experiment system with a transparent scaled-up vertical multi-hole injector nozzle tip was setup. A high resolution and speed CCD camera equipped with a long distance microscope device was used to acquire flow images of diesel and biodiesel fuel, respectively. Then, the characteristics of cavitating flow and their effects on the fuel atomization characteristics were investigated. The experimental results show that the nozzle cavitating flow of both the diesel and biodiesel fuel could be divided into four regimes: turbulent flow, cavitation inception, development of cavitation and hydraulic flip. The critical pressures of both the cavitating flow and hydraulic flip of biodiesel are higher than those of diesel. The spray cone angle increases as the cavitation occurs, but it decreases when the hydraulic flip appears. Finally, it can be concluded that the Reynolds number decreases with the increase of cavitation number, and the discharge coefficient increases with the increase of cavitation number.

  4. Numerical analysis of critical two-phase flow in a convergent-divergent nozzle

    International Nuclear Information System (INIS)

    Romstedt, P.; Werner, W.

    1985-01-01

    The numerical calculation of critical two-phase flow in a convergent-divergent nozzle is complicated by a singularity of the fluid flow equations at the unknown critical point. This paper describes a method which is able to calculate critical state and its location without any additional assumptions. The critical state is identified by its mathematical properties: characteristics and solvability of linear systems with singular matrix. Because the numerically evaluable mathematical properties are only necessary conditions for the existence of critical flow, some physical ''compatibility-criteria'' (flow velocity equals two-phase sonic velocity, critical flow is independent of downstream flow state variations) are used as a substitute for mathematically sufficient conditions. Numerical results are shown for the critical flow in a LOBI nozzle; the two-phase flow is described by a model with equal phase velocities and thermodynamic non-equilibrium

  5. Three layer model analysis on two-phase critical flow through a converging nozzle

    International Nuclear Information System (INIS)

    Ochi, J.; Ayukawa, K.

    1991-01-01

    A three layer model is proposed for a two-phase critical flow through a converging nozzle in this paper. Most previous analyses of the two phase flow have been based on a homogeneous or a separated flow model as the conservation equations. These results were found to have large deviations from the actual measurements for two phase critical flows. The presented model is based on the assumption that a flow consists of three layers with a mixing region between gas and liquid phase layers. The effect of gas and liquid fraction occupied in the mixing layer was made clear from the numerical results. The measurements of the critical flow rate and the pressure profiles through a converging nozzle were made with air-water flow. The calculated results of these models are discussed in comparison with the experimental data for the flow rates and the pressure distributions under critical conditions

  6. An analytical evaluation for the pressure drop characteristics of bottom nozzle flow holes

    International Nuclear Information System (INIS)

    Yang, S. G.; Kim, H. J.; Lim, H. T.; Park, E. J.; Jeon, K. L.

    2002-01-01

    An analytical evaluation for the bottom nozzle flow holes was performed to find a best design concept in terms of pressure drop. For this analysis, Computational Fluid Dynamics (CFD), FLUENT 5.5, code was selected as an analytical evaluation tool. The applicability of CFD code was verified by benchmarking study with Vibration Investigation of Small-scale Test Assemblies (VISTA) test data in several flow conditions and typical flow hole shape. From this verification, the analytical data were benchmarked roughly within 17% to the VISTA test data. And, overall trend under various flow conditions looked very similar between both cases. Based on the evaluated results using CFD code, it is concluded that the deburring and multiple chamfer hole features at leading edge are the excellent design concept to decrease pressure drop across bottom nozzle plate. The deburring and multiple chamfer hole features at leading edge on the bottom nozzle plate have 12% and 17% pressure drop benefit against a single chamfer hole feature on the bottom nozzle plate, respectively. These design features are meaningful and applicable as a low pressure drop design concept of bottom nozzle for Pressurized Water Reactor (PWR) fuel assembly

  7. Advanced Supersonic Nozzle Concepts: Experimental Flow Visualization Results Paired With LES

    Science.gov (United States)

    Berry, Matthew; Magstadt, Andrew; Stack, Cory; Gaitonde, Datta; Glauser, Mark; Syracuse University Team; The Ohio State University Team

    2015-11-01

    Advanced supersonic nozzle concepts are currently under investigation, utilizing multiple bypass streams and airframe integration to bolster performance and efficiency. This work focuses on the parametric study of a supersonic, multi-stream jet with aft deck. The single plane of symmetry, rectangular nozzle, displays very complex and unique flow characteristics. Flow visualization techniques in the form of PIV and schlieren capture flow features at various deck lengths and Mach numbers. LES is compared to the experimental results to both validate the computational model and identify limitations of the simulation. By comparing experimental results to LES, this study will help create a foundation of knowledge for advanced nozzle designs in future aircraft. SBIR Phase II with Spectral Energies, LLC under direction of Barry Kiel.

  8. Droplet phase characteristics in liquid-dominated steam--water nozzle flow

    International Nuclear Information System (INIS)

    Alger, T.W.

    1978-01-01

    An experimental study was undertaken to determine the droplet size distribution, the droplet spatial distribution and the mean droplet velocity in low-quality, steam-water flow from a rectangular cross-section, converging-diverging nozzle. A unique forward light scattering technique was developed for droplet size distribution measurements. Droplet spatial variations were investigated using light transmission measurements, and droplet velocities were measured with a laser-Doppler velocimeter (LDV) system incorporating a confocal Fabry-Perot interferometer. Nozzle throat radius of curvature and height were varied to investigte their effects on droplet size. Droplet size distribution measurements yielded a nominal Sauter mean droplet diameter of 1.7 μm and a nominal mass-mean droplet diameter of 2.4 μm. Neither the throat radius of curvature nor the throat height were found to have a significant effect upon the nozzle exit droplet size. The light transmission and LDV measurement results confirmed both the droplet size measurements and demonstrated high spatial uniformity of the droplet phase within the nozzle jet flow. One-dimensional numerical calculations indicated that both the dynamic breakup (thermal equilibrium based on a critical Weber number of 6.0) and the boiling breakup (thermal nonequilibrium based on average droplet temperature) models predicted droplet diameters on the order of 7.5 μm, which are approximately equal to the maximum stable droplet diameters within the nozzle jet flow

  9. Numerical Study of Controlling Jet Flow and Noise using Pores on Nozzle Inner Wall

    Science.gov (United States)

    Lin, Jian; Shi, Zhixiao; Lai, Huanxin

    2018-04-01

    In this paper, the feasibility of controlling the subsonic jet flow and its noise using pores of blind holes added on the nozzle inner wall is explored numerically. These pores are intended to introduce disturbances to the shear layer so as to change the flow mixing. This passive strategy has not been attempted so far. A convergent nozzle with a cylindrical extension is selected as the baseline case. Three nozzles with pores on the inner wall are set up. Validations of the numerical settings are carried out, then the compressible turbulent jets at the exit Mach number M j = 0.6 in the four nozzles are calculated by large eddy simulations (LES), while the radiated sounds are predicted by the FW-H acoustic analogy. The results show that the blind holes have produced some effects on weakening the turbulence intensity in the shear layer. Comparison reveals that both temporal and spatial correlations of the turbulent fluctuations in the modified cases are suppressed to some extent. Meanwhile, the porous nozzles are shown to suppress the pairing of vortices and enhance the flow mixing, and therefore, the development of shear layer and the fragmentation of large scale vortices are accelerated.

  10. In-nozzle flow and spray characteristics for mineral diesel, Karanja, and Jatropha biodiesels

    International Nuclear Information System (INIS)

    Agarwal, Avinash Kumar; Som, Sibendu; Shukla, Pravesh Chandra; Goyal, Harsh; Longman, Douglas

    2015-01-01

    Highlights: • In-nozzle flow characterization for biodiesel sprays. • Comparison of experimental spray parameters and nozzle hole simulations. • Effect of Karanja and Jatropha biodiesel on in-nozzle cavitation. • Cavitation formation investigation with diesel and biodiesels. • Nozzle hole outlet fuel velocity profile determination for test fuels. - Abstract: Superior spray behavior of fuels in internal combustion engines lead to improved combustion and emission characteristics therefore it is necessary to investigate fuel spray behavior of new alternative fuels. This study discusses the evolution of the in-nozzle orifice parameters of a numerical simulation and the evolution of spray parameters of fuel spray in a constant-volume spray chamber during an experiment. This study compares mineral diesel, biodiesels (Karanja-and Jatropha-based), and their blends with mineral diesel. The results show that mineral diesel provides superior atomization and evaporation behavior compared to the biodiesel test fuels. Karanja biodiesel provides superior atomization and evaporation characteristics compared to Jatropha biodiesel. The qualitative comparison of simulation and experimental results in tandem shows that nozzle-hole design is a critical parameter for obtaining optimum spray behavior in the engine combustion chamber

  11. Numerical investigation of the variable nozzle effect on the mixed flow turbine performance characteristics

    Science.gov (United States)

    Meziri, B.; Hamel, M.; Hireche, O.; Hamidou, K.

    2016-09-01

    There are various matching ways between turbocharger and engine, the variable nozzle turbine is the most significant method. The turbine design must be economic with high efficiency and large capacity over a wide range of operational conditions. These design intents are used in order to decrease thermal load and improve thermal efficiency of the engine. This paper presents an original design method of a variable nozzle vane for mixed flow turbines developed from previous experimental and numerical studies. The new device is evaluated with a numerical simulation over a wide range of rotational speeds, pressure ratios, and different vane angles. The compressible turbulent steady flow is solved using the ANSYS CFX software. The numerical results agree well with experimental data in the nozzleless configuration. In the variable nozzle case, the results show that the turbine performance characteristics are well accepted in different open positions and improved significantly in low speed regime and at low pressure ratio.

  12. THE APPLICATION OF LASERS IN MEASUREMENT OF FLUID FLOW THROUGH DRILLING BIT NOZZLES

    Directory of Open Access Journals (Sweden)

    Radenko Drakulić

    1993-12-01

    Full Text Available Two optical methods based on laser and video technology and digital signal and image processing techniques - Laser Doppler velocimetry (LDV and Particle image velocimetry (PIV were applied in highly accurate fluid flow measurement. Their application in jet velocity measurement of flows through drilling bit nozzles is presented. The role of nozzles in drilling technology together with procedures and tests performed on their optimization are reviewed. In addition, some experimental results for circular nozzle obtained both with LDV and PIV are elaborated. The experimental set-up and the testing procedure arc briefly discussed, as well as potential improvements in the design. Possible other applications of LDV and PIV in the domain of petroleum engineering are suggested (the paper is published in Croatian.

  13. Isentropic Gas Flow for the Compressible Euler Equation in a Nozzle

    Science.gov (United States)

    Tsuge, Naoki

    2013-08-01

    We study the motion of isentropic gas in a nozzle. Nozzles are used to increase the thrust of engines or to accelerate a flow from subsonic to supersonic. Nozzles are essential parts for jet engines, rocket engines and supersonicwind tunnels. In the present paper, we consider unsteady flow, which is governed by the compressible Euler equation, and prove the existence of global solutions for the Cauchy problem. For this problem, the existence theorem has already been obtained for initial data away from the sonic state, (Liu in Commun Math Phys 68:141-172, 1979). Here, we are interested in the transonic flow, which is essential for engineering and physics. Although the transonic flow has recently been studied (Tsuge in J Math Kyoto Univ 46:457-524, 2006; Lu in Nonlinear Anal Real World Appl 12:2802-2810, 2011), these papers assume monotonicity of the cross section area. Here, we consider the transonic flow in a nozzle with a general cross section area. When we prove global existence, the most difficult point is obtaining a bounded estimate for approximate solutions. To overcome this, we employ a new invariant region that depends on the space variable. Moreover, we introduce a modified Godunov scheme. The corresponding approximate solutions consist of piecewise steady-state solutions of an auxiliary equation, which yield a desired bounded estimate. In order to prove their convergence, we use the compensated compactness framework.

  14. Numerical simulation of internal and near-nozzle flow of a gasoline direct injection fuel injector

    Science.gov (United States)

    Saha, Kaushik; Som, Sibendu; Battistoni, Michele; Li, Yanheng; Quan, Shaoping; Senecal, Peter Kelly

    2015-12-01

    A numerical study of two-phase flow inside the nozzle holes and the issuing spray jets for a multi-hole direct injection gasoline injector has been presented in this work. The injector geometry is representative of the Spray G nozzle, an eight-hole counterbore injector, from, the Engine Combustion Network (ECN). Simulations have been carried out for the fixed needle lift. Effects of turbulence, compressibility and, non-condensable gases have been considered in this work. Standard k—ɛ turbulence model has been used to model the turbulence. Homogeneous Relaxation Model (HRM) coupled with Volume of Fluid (VOF) approach has been utilized to capture the phase change phenomena inside and outside the injector nozzle. Three different boundary conditions for the outlet domain have been imposed to examine non-flashing and evaporative, non-flashing and non-evaporative, and flashing conditions. Inside the nozzle holes mild cavitation-like and in the near-nozzle region flash boiling phenomena have been predicted in this study when liquid fuel is subjected to superheated ambiance. Noticeable hole to hole variation has been also observed in terms of mass flow rates for all the holes under both flashing and non-flashing conditions.

  15. Development of supersonic plasma flows by use of a magnetic nozzle and an ICRF heating

    Energy Technology Data Exchange (ETDEWEB)

    Inutake, M.; Ando, A.; Hattori, K.; Tobari, H.; Hosokawa, Y.; Sato, R.; Hatanaka, M.; Harata, K. [Tohoku Univ., Dept. of Electrical Engineering, Sendai (Japan)

    2004-07-01

    A high-beta, supersonic plasma flow plays a crucial role in MHD phenomena in space and fusion plasmas. There are a few experimental researches on production and control of a fast flowing plasma in spite of a growing significance in the magnetized-plasma flow dynamics. A magneto-plasma-dynamic arc-jet (MPDA) is one of promising devices to produce a supersonic plasma flow and has been utilized as an electric propulsion device with a higher specific impulse and a relatively larger thrust. We have improved the performance of an MPDA to produce a quasi-steady plasma flow with a transonic and supersonic Mach number in a highly-ionized state. There are two methods in order to control an ion-acoustic Mach number of the plasma flow exhausted from an MPDA: one is to use a magnetic Laval nozzle to convert a thermal energy to a flow energy and the other is a combined system of an ion heating and a divergent magnetic nozzle. The former is an analogous method to a compressible air flow and the latter is the method proposed in an advanced thruster for a manned interplanetary space mission. We have clarified the plasma flow characteristics in various shapes of a magnetic field configuration. It was demonstrated that the Mach number of the plasma flow could increase up to almost 3 in a divergent magnetic nozzle field. This paper reports recent results on the flow field improvements: one is on a magnetic-Laval-nozzle effects observed at the muzzle region of the MPDA, and the other is on ICRF (ion-cyclotron-range of frequency) heating of a supersonic plasma by use of a helical antenna. (authors)

  16. Testing and qualification of CIRCE venturi-nozzle flow meter for large scale experiments

    International Nuclear Information System (INIS)

    Ambrosini, W.; Forgione, N.; Oriolo, F.; Tarantino, M.; Agostini, P.; Benamati, G.; Bertacci, G.; Elmi, N.; Alemberti, A.; Cinotti, L.; Scaddozzo, G.

    2005-01-01

    This paper is focused on the tests carried out at the ENEA Brasimone Centre for the qualification of a large Venturi-Nozzle flow meter operating in Lead Bismuth Eutectic (LBE). Such flow meter has been selected to provide flow rate measurements during the thermal-hydraulic tests that will be performed on the experimental facility CIRCE. This large-scale facility is installed at the ENEA Brasimone Centre for studying the fluid-dynamics and operating behaviour of ADS reactor plants, as well as to qualify several components intended to be used in the LBE technology. The Venturi-Nozzle flow meter has been supplied by the Euromisure s.r.l., together with the calculated theoretical characteristic equation. The results obtained by the tests performed allowed to qualify this theoretical curve supplied by the manufacturer, that presents a very good agreement especially at high flow rate values. (authors)

  17. Flow regime effects on non-cavitating injection nozzles over spray behavior

    Energy Technology Data Exchange (ETDEWEB)

    Payri, R., E-mail: rpayri@mot.upv.e [CMT-Motores Termicos, Universidad Politecnica de Valencia, Camino de Vera s/n, Valencia E-46022 (Spain); Salvador, F.J.; Gimeno, J.; Novella, R. [CMT-Motores Termicos, Universidad Politecnica de Valencia, Camino de Vera s/n, Valencia E-46022 (Spain)

    2011-02-15

    This paper deals with the influence of flow regime (laminar, transition or turbulent) on the internal flow behavior, and how it affects the spray development in diesel nozzles. In particular, the research described here aims at studying and quantifying the internal flow regime effects on the spray behavior. With this purpose, internal flow results, based on mass flow rate and momentum flux measurements performed on three different tapered nozzles and which helped to determine the flow regime, has been taken into account as a point of departure for the spray behavior analysis. Thus, in this work, spray macroscopic visualization tests have been performed and analyzed which clearly revealed a change in the behavior of the angle and penetration of the spray related to the change of the flow nature. Moreover, with all the experimental data available, it has been possible to relate macroscopic parameters of the spray with those describing the internal flow (momentum and effective velocity) or the geometry of the nozzle (length or diameter) through correlations.

  18. Numerical study for two phase flow in the near nozzle region of turbine combustors

    International Nuclear Information System (INIS)

    Pervez, K.; Mushtaq, S.

    1999-01-01

    In the present study flow conditions in the near nozzle region of the combustion chamber have been investigated. There exists two-phase flow in this region. The overall performance and pollutant formation in the combustion chamber have been investigated. There exists two-phase flow in this region. The overall performance and pollutant formation in the combustion zone largely depends on the spray field in the near nozzle region the studies are conducted to determined the effects of multi jets on the flow pattern in the near nozzle region The phase doppler particle analyzer (PDPA) has been used to measure the velocities and sizes of the droplets. The flow field of two-phase liquid drop-air jets is formed from three injectors arranged in t line. Furthermore the two-phase flow field has been analyzed numerically also. The numerical analysis consists of two computational models, namely (i) 3 non-evaporating two-phase jets, (II) 3 evaporating two phase jets. The Eulerian-Eulerian approach in incorporated in both the numerical models. Since the flow is turbulent, a two-equation model (k-Epsilon) is implemented in the numerical analysis. Numerical solution of the conservation equation is obtained using PHOENICS computer code. Boundary conditions are provided from the experimental measurements. Numerical domain for the two models of the analysis starts at some distance (about 10 diameters of the injector orifice) where the atomization process is complete and droplet size and velocity could be measured experimentally. (author)

  19. Indirect Combustion Noise: Noise Generation by Accelerated Vorticity in a Nozzle Flow

    Directory of Open Access Journals (Sweden)

    Nancy Kings

    2010-09-01

    Full Text Available The noise generation by accelerated vorticity waves in a nozzle flow was investigated in a model experiment. This noise generation mechanism belongs, besides entropy noise, to the indirect combustion noise phenomena. Vorticity as well as entropy fluctuations, originating from the highly turbulent combustion zone, are convected with the flow and produce noise during their acceleration in the outlet nozzle of the combustion chamber. In the model experiment, noise generation of accelerated vorticity fluctuations was achieved. The vorticity fluctuations in the tube flow were produced by injecting temporally additional air into the mean flow. As the next step, a parametric study was conducted to determine the major dependencies of the so called vortex noise. A quadratic dependency of the vortex noise on the injected air amount was found. In order to visualise and classify the artificially generated vorticity structures, planar velocity measurements have been conducted applying Particle Image Velocimetry (PIV.

  20. Prediction of sonic flow conditions at drill bit nozzles to minimize complications in UBD

    Energy Technology Data Exchange (ETDEWEB)

    Guo, B.; Ghalambor, A. [Louisiana Univ., Lafayette, LA (United States); Al-Bemani, A.S. [Sultan Qaboos Univ. (Oman)

    2002-06-01

    Sonic flow at drill bit nozzles can complicate underbalanced drilling (UBD) operations, and should be considered when choosing bit nozzles and fluid injection rates. The complications stem from pressure discontinuity and temperature drop at the nozzle. UBD refers to drilling operations where the drilling fluid pressures in the borehole are maintained at less than the pore pressure in the formation rock in the open-hole section. UBD has become a popular drilling method because it offers minimal lost circulation and reduces formation damage. This paper presents an analytical model for calculating the critical pressure ratio where two-phase sonic flow occurs. In particular, it describes how Sachdeva's two-phase choke model can be used to estimate the critical pressure ratio at nozzles that cause sonic flow. The critical pressure ratio charts can be coded in spreadsheets. The critical pressure ratio depends on the in-situ volumetric gas content, or gas-liquid ratio, which depends on gas injection and pressure. 6 refs., 2 tabs., 5 figs.

  1. Fuel nozzle assembly

    Science.gov (United States)

    Johnson, Thomas Edward [Greer, SC; Ziminsky, Willy Steve [Simpsonville, SC; Lacey, Benjamin Paul [Greer, SC; York, William David [Greer, SC; Stevenson, Christian Xavier [Inman, SC

    2011-08-30

    A fuel nozzle assembly is provided. The assembly includes an outer nozzle body having a first end and a second end and at least one inner nozzle tube having a first end and a second end. One of the nozzle body or nozzle tube includes a fuel plenum and a fuel passage extending therefrom, while the other of the nozzle body or nozzle tube includes a fuel injection hole slidably aligned with the fuel passage to form a fuel flow path therebetween at an interface between the body and the tube. The nozzle body and the nozzle tube are fixed against relative movement at the first ends of the nozzle body and nozzle tube, enabling the fuel flow path to close at the interface due to thermal growth after a flame enters the nozzle tube.

  2. Five-hole pitot probe measurements of swirl, confinement and nozzle effects on confined turbulent flow

    Science.gov (United States)

    Lilley, D. G.; Scharrer, G. L.

    1984-01-01

    The results of a time-mean flow characterization of nonswirling and swirling inert flows in a combustor are reported. The five-hole pitot probe technique was used in axisymmetric test sections with expansion ratios of 1 and 1.5. A prominent corner recirculation zone identified in nonswirling expanding flows decreased in size with swirling flows. The presence of a downstream nozzle led to an adverse pressure gradient at the wall and a favorable gradient near the centerline. Reducing the expansion ratio reduced the central recirculation length. No significant effect was introduced in the flowfield by a gradual expansion.

  3. Numerical investigation of over expanded flow behavior in a single expansion ramp nozzle

    Science.gov (United States)

    Mousavi, Seyed Mahmood; Pourabidi, Reza; Goshtasbi-Rad, Ebrahim

    2018-05-01

    The single expansion ramp nozzle is severely over-expanded when the vehicle is at low speed, which hinders its ability to provide optimal configurations for combined cycle engines. The over-expansion leads to flow separation as a result of shock wave/boundary-layer interaction. Flow separation, and the presence of shocks themselves, result in a performance loss in the single expansion ramp nozzle, leading to reduced thrust and increased pressure losses. In the present work, the unsteady two dimensional compressible flow in an over expanded single expansion ramp nozzle has been investigated using finite volume code. To achieve this purpose, the Reynolds stress turbulence model and full multigrid initialization, in addition to the Smirnov's method for examining the errors accumulation, have been employed and the results are compared with available experimental data. The results show that the numerical code is capable of predicting the experimental data with high accuracy. Afterward, the effect of discontinuity jump in wall temperature as well as the length of straight ramp on flow behavior have been studied. It is concluded that variations in wall temperature and length of straight ramp change the shock wave boundary layer interaction, shock structure, shock strength as well as the distance between Lambda shocks.

  4. Effect of fuel temperature on the methanol spray and nozzle internal flow

    International Nuclear Information System (INIS)

    Chen, Zhifang; Yao, Anren; Yao, Chunde; Yin, Zenghui; Xu, Han; Geng, Peilin; Dou, Zhancheng; Hu, Jiangtao; Wu, Taoyang; Ma, Ming

    2017-01-01

    Highlights: • Cavitation region increases with the increasing of methanol temperature. • The nozzle exit velocity increases with the increasing of methanol temperature. • The discharge coefficient decreases with the increasing of methanol temperature. • Droplet SMD reduces when methanol temperature increases measured by PDPA system. • Droplet velocity has the maximum value when methanol temperature is 60 °C. - Abstract: The increasing of fuel temperature can reduce the droplet size and have an advantage of improving spray atomization, while investigations of the effect of temperature on the methanol injector internal flow and external spray is rare. Firstly, a detailed three dimensional numerical simulations of nozzle internal flow have been conducted to probe into the cavitation in methanol injector nozzles, and then an experimental study has been carried out to investigate the droplet size and velocity of methanol spray at various temperatures using the Phase Doppler Particle Analyzer (PDPA) detecting system. And results show that the region of cavitations in nozzle orifice enlarges as methanol temperature and injection pressure increases, and the temperature for 'super-cavitation' occurring decreases gradually with the increasing of injection pressure. Moreover, the nozzle exit velocity, discharge coefficient and cavitations number were also analyzed. However, the discharge coefficient reduces nearly equal under various pressure when the methanol temperature is higher than 60 °C. In addition, the Sauter Mean Diameter (SMD) and velocity of methanol droplet were also analyzed, and found that the droplet velocity reaches the maximum value when the methanol temperature is 60 °C.

  5. Structure of the gas-liquid annular two-phase flow in a nozzle section

    International Nuclear Information System (INIS)

    Yoshida, Kenji; Kataoka, Isao; Ohmori, Syuichi; Mori, Michitsugu

    2006-01-01

    Experimental studies on the flow behavior of gas-liquid annular two-phase flow passing through a nozzle section were carried out. This study is concerned with the central steam jet injector for a next generation nuclear reactor. In the central steam jet injector, steam/water annular two-phase flow is formed at the mixing nozzle. To make an appropriate design and to establish the high-performance steam injector system, it is very important to accumulate the fundamental data of the thermo-hydro dynamic characteristics of annular flow passing through a nozzle section. On the other hand, the transient behavior of multiphase flow, in which the interactions between two-phases occur, is one of the most interesting scientific issues and has attracted research attention. In this study, the transient gas-phase turbulence modification in annular flow due to the gas-liquid phase interaction is experimentally investigated. The annular flow passing through a throat section is under the transient state due to the changing cross sectional area of the channel and resultantly the superficial velocities of both phases are changed compared with a fully developed flow in a straight pipe. The measurements for the gas-phase turbulence were precisely performed by using a constant temperature hot-wire anemometer, and made clear the turbulence structure such as velocity profiles, fluctuation velocity profiles. The behavior of the interfacial waves in the liquid film flow such as the ripple or disturbance waves was also observed. The measurements for the liquid film thickness by the electrode needle method were also performed to measure the base film thickness, mean film thickness, maximum film thickness and wave height of the ripple or the disturbance waves. (author)

  6. The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow

    KAUST Repository

    Elbaz, Ayman M.

    2015-08-29

    The stability limits, the stabilization mechanism, and the flow field structure of highly stabilized partially premixed methane flames in a concentric flow conical nozzle burner with air co-flow have been investigated and presented in this work. The stability map of partial premixed flames illustrates that the flames are stable between two extinction limits. A low extinction limit when partial premixed flames approach non-premixed flame conditions, and a high extinction limit, with the partial premixed flames approach fully premixed flame conditions. These two limits showed that the most stable flame conditions are achieved at a certain degree of partial premixed. The stability is improved by adding air co-flow. As the air co-flow velocity increases the most stable flames are those that approach fully premixed. The turbulent flow field of three flames at 0, 5, 10 m/s co-flow velocity are investigated using Stereo Particle Image Velocimetry (SPIV) in order to explore the improvement of the flame stability due to the use of air co-flow. The three flames are all at a jet equivalence ratio (Φj) of 2, fixed level of partial premixing and jet Reynolds number (Rej) of 10,000. The use of co-flow results in the formation of two vortices at the cone exit. These vortices act like stabilization anchors for the flames to the nozzle tip. With these vortices in the flow field, the reaction zone shifts toward the reduced turbulence intensity at the nozzle rim of the cone. Interesting information about the structure of the flow field with and without co-flow are identified and reported in this work.

  7. The characterisation of diesel nozzle flow using high speed imaging of elastic light scattering

    OpenAIRE

    Lockett, R. D.; Liverani, L.; Thaker, D.; Jeshani, M.; Tait, N. P.

    2013-01-01

    Two identical, conventional six-hole, valve-covered orifice (VCO) diesel injectors have been modified in order to provide optical access to the region below the needle, and the nozzle-flow passages. This has been achieved through the removal of the metal tips, and their replacement with transparent acrylic tips of identical geometry. \\ud \\ud These two identical injectors were employed in order to offer comparability between the measurements. One of them had a dark, anodised inner surface at t...

  8. Influence of biofuels on the internal flow in diesel injector nozzles

    OpenAIRE

    Salvador, F.J.; Martínez López, Jorge; Romero Bauset, José Vicente; Roselló, M.D.

    2011-01-01

    [EN] In this paper, the behavior of the internal nozzle flow of a standard diesel fuel has been compared against a biodiesel fuel (soybean oil) at cavitating and non-cavitating conditions, using a homogeneous equilibrium model. The model takes into account the compressibility of both phases (liquid and vapour) and use a barotropic equation of state which relates pressure and density to calculate the growth of cavitation. Furthermore, turbulence effects have been introduced using a RNG k- ¿ mo...

  9. Visualization of Atomization Gas Flow and Melt Break-up Effects in Response to Nozzle Design

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver; Rieken, Joel; Meyer, John; Byrd, David; Heidloff, Andy

    2011-04-01

    Both powder particle size control and efficient use of gas flow energy are highly prized goals for gas atomization of metal and alloy powder to minimize off-size powder inventory (or 'reverb') and excessive gas consumption. Recent progress in the design of close-coupled gas atomization nozzles and the water model simulation of melt feed tubes were coupled with previous results from several types of gas flow characterization methods, e.g., aspiration measurements and gas flow visualization, to make progress toward these goals. Size distribution analysis and high speed video recordings of gas atomization reaction synthesis (GARS) experiments on special ferritic stainless steel alloy powders with an Ar+O{sub 2} gas mixture were performed to investigate the operating mechanisms and possible advantages of several melt flow tube modifications with one specific gas atomization nozzle. In this study, close-coupled gas atomization under closed wake gas flow conditions was demonstrated to produce large yields of ultrafine (dia.<20 {mu}m) powders (up to 32%) with moderate standard deviations (1.62 to 1.99). The increased yield of fine powders is consistent with the dual atomization mechanisms of closed wake gas flow patterns in the near-field of the melt orifice. Enhanced size control by stabilized pre-filming of the melt with a slotted trumpet bell pour tube was not clearly demonstrated in the current experiments, perhaps confounded by the influence of the melt oxidation reaction that occurred simultaneously with the atomization process. For this GARS variation of close-coupled gas atomization, it may be best to utilize the straight cylindrical pour tube and closed wake operation of an atomization nozzle with higher gas mass flow to promote the maximum yields of ultrafine powders that are preferred for the oxide dispersion strengthened alloys made from these powders.

  10. Oscillations of the fluid flow and the free surface in a cavity with a submerged bifurcated nozzle

    International Nuclear Information System (INIS)

    Kalter, R.; Tummers, M.J.; Kenjereš, S.; Righolt, B.W.; Kleijn, C.R.

    2013-01-01

    Highlights: • Self-sustained oscillations in a thin cavity with submerged nozzle were observed. • Three flow regimes are detected depending on nozzle depth and inlet velocity. • The three flow regimes have been summarized in a flow regime map. • PIV measurements are performed to link free surface behavior to the bulk-flow. • We report a close correlation between jet-behavior and free surface dynamics. -- Abstract: The free surface dynamics and sub-surface flow behavior in a thin (height and width much larger than thickness), liquid filled, rectangular cavity with a submerged bifurcated nozzle were investigated using free surface visualization and particle image velocimetry (PIV). Three regimes in the free surface behavior were identified, depending on nozzle depth and inlet velocity. For small nozzle depths, an irregular free surface is observed without clear periodicities. For intermediate nozzle depths and sufficiently high inlet velocities, natural mode oscillations consistent with gravity waves are present, while at large nozzle depths long term self-sustained asymmetric oscillations occur. For the latter case, time-resolved PIV measurements of the flow below the free surface indicated a strong oscillation of the direction with which each of the two jets issue from the nozzle. The frequency of the jet oscillation is identical to the free surface oscillation frequency. The two jets oscillate in anti-phase, causing the asymmetric free surface oscillation. The jets interact through a cross-flow in the gaps between the inlet channel and the front and back walls of the cavity

  11. Propagation of temperature disturbances in bounded flows downstream of a nozzle block

    International Nuclear Information System (INIS)

    Krebs, L.

    1979-12-01

    The early detection of cooling disturbances in a fuel element of a sodium cooled reactor is a must for safety reasons. One possibility of achieving this goal is by measuring and analyzing the coolant temperature at the fuel element outlet. Assessment of the potential of this method requires knowledge of the flow phenomena downstream of the fuel element. As a fluid dynamics model of a fuel element a nozzle block is used, the bores of which correspond to the subchannels between the fuel rods. The studies are conducted in water which has kinematic properties comparable to those of sodium. The velocity and temperature fields downstream of the nozzle block are examined for two REYNOLDS numbers. To simulate a disturbed cooling condition, water with a temperature higher by ΔT anti T = 10 K is injected through one subchannel of the nozzle block. At the same time, the volume injected is varied. The central channel and one side channel close to the wall are selected as injection sites. Statisticl analysis of the measured velocity and temperature signals covers the following parameters: Linear averages, intensities, probability densities, spectral power densities, autocorrelation functions, integral turbulence lengths, dissipation lengths, dissipation, skewness and flatness values. On the basis of FOURIER's differential equation of heat conduction a theoretical model is developed to describe both the average temperature field and the intensity field in the flow downstream of the nozzle block. Comparison of measurements and calculations furnishes good agreement and indicates that extrapolation of the model to sodium as a fluid is possible. Supplementary to the measurements and calculations details of the water test rig and the anemometer measuring system used for velocity and temperature measurements are shown in the Appendix. (orig.) 891 GL/orig. 892 KN [de

  12. Cavitation characteristics of multihole diesel-fuel nozzles in high-speed oil flows. Diesel kikan yo nenryo tako nozzle no abura cavitation tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Yokota, M. (Shimonoseki Univ. of Fisheris, Yamaguchi (Japan)); Ito, Y. (Hachinohe Inst. of Tech., Aomori (Japan)); Aoki, H. (Xexel-Gleason U.S.A. Inc., New York (U.S.A))

    1991-07-25

    Recently, since higher velocity and higher pressure are required for diesel injection systems, cavitation behaviors in high velocity oil flows are strongly interested in such as 100 to 500 m/s for oil flow velocity and less than the cavitation factor {sigma} of 0.01. In this paper, oil cavitation characteristics at the injection part of multihole nozzles, especially on the flow characteristics, were studied systematically using fuel injection multihole nozzles for an actual use. As a result, it was clarified that subcavitation area (sub C), transition area, and supercavitation area (SC) could be existing in C{sub d}-{sigma} relation, which was similar to that specified cavitation conditions could be exisiting in the actual working area of multihole nozzles. And it was also clarified that flow coefficient C{sub d} relied on Reynolds number R{sub e} in the transition of {sigma}{ge}{sigma}{sub cr} and in {sub C} area, and mainly relied on {sigma} in SC area of {sigma}<{sigma}{sub cr}. Moreover, it was also confirmed that such tendency was similar to the one of the two-dimensional contraction of an area. 22 refs., 10 figs., 1 tab.

  13. Three-dimensional analysis of internal flow characteristics in the injection nozzle tip of direct-injection diesel engines; Sanjigen suchi kaiseki ni yoru DI diesel kikan no nenryo funsha nozzle nai ryudo tokusei no kaimei

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, H; Matsui, Y; Kimura, S [Nissan Motor Co. Ltd. Tokyo (Japan)

    1997-10-01

    To reduce the exhaust emissions and fuel consumption of direct-injection diesel engines, it is essential to optimize the fuel injection equipment closely related to combustion and emission characteristics. In this study, three-dimensional computation has been applied to investigate the effects of the injection nozzle specifications (e.g., sac volume, round shape at the inlet of the nozzle hole) and needle tip deviation on internal flow characteristics. The computational results revealed that the effects of the nozzle specifications and needle tip deviation with a smaller needle lift on internal flow characteristics and a general approach to optimize the injection nozzle specifications were obtained. 3 refs., 10 figs., 1 tab.

  14. Computational Fluid Dynamic (CFD) analysis of axisymmetric plume and base flow of film/dump cooled rocket nozzle

    Science.gov (United States)

    Tucker, P. K.; Warsi, S. A.

    1993-01-01

    Film/dump cooling a rocket nozzle with fuel rich gas, as in the National Launch System (NLS) Space Transportation Main Engine (STME), adds potential complexities for integrating the engine with the vehicle. The chief concern is that once the film coolant is exhausted from the nozzle, conditions may exist during flight for the fuel-rich film gases to be recirculated to the vehicle base region. The result could be significantly higher base temperatures than would be expected from a regeneratively cooled nozzle. CFD analyses were conduced to augment classical scaling techniques for vehicle base environments. The FDNS code with finite rate chemistry was used to simulate a single, axisymmetric STME plume and the NLS base area. Parallel calculations were made of the Saturn V S-1 C/F1 plume base area flows. The objective was to characterize the plume/freestream shear layer for both vehicles as inputs for scaling the S-C/F1 flight data to NLS/STME conditions. The code was validated on high speed flows with relevant physics. This paper contains the calculations for the NLS/STME plume for the baseline nozzle and a modified nozzle. The modified nozzle was intended to reduce the fuel available for recirculation to the vehicle base region. Plumes for both nozzles were calculated at 10kFT and 50kFT.

  15. Assessment of NASA and RAE viscous-inviscid interaction methods for predicting transonic flow over nozzle afterbodies

    Science.gov (United States)

    Putnam, L. E.; Hodges, J.

    1983-01-01

    The Langley Research Center of the National Aeronautics and Space Administration and the Royal Aircraft Establishment have undertaken a cooperative program to conduct an assessment of their patched viscous-inviscid interaction methods for predicting the transonic flow over nozzle afterbodies. The assessment was made by comparing the predictions of the two methods with experimental pressure distributions and boattail pressure drag for several convergent circular-arc nozzle configurations. Comparisons of the predictions of the two methods with the experimental data showed that both methods provided good predictions of the flow characteristics of nozzles with attached boundary layer flow. The RAE method also provided reasonable predictions of the pressure distributions and drag for the nozzles investigated that had separated boundary layers. The NASA method provided good predictions of the pressure distribution on separated flow nozzles that had relatively thin boundary layers. However, the NASA method was in poor agreement with experiment for separated nozzles with thick boundary layers due primarily to deficiencies in the method used to predict the separation location.

  16. Effect of jet nozzle geometry on flow and heat transfer performance of vortex cooling for gas turbine blade leading edge

    International Nuclear Information System (INIS)

    Du, Changhe; Li, Liang; Wu, Xin; Feng, Zhenping

    2016-01-01

    Highlights: • We establish a suitable vortex chamber model for gas turbine blade leading edge. • Mechanism of vortex cooling is further discussed and presented. • Influences of jet nozzle geometry on vortex cooling characteristics are researched. • This paper focuses on assessment of flow field and thermal performance for different jet nozzle aspect ratio and area. - Abstract: In this paper, 3D viscous steady Reynolds Averaged Navier–Stokes (RANS) equations are utilized to investigate the influence of jet nozzle geometry on flow and thermal behavior of vortex cooling for gas turbine blades. Comparison between calculation with different turbulence models and the experimental data is conducted, and results show that the standard k-ω model provides the best accuracy. The grid independence analysis is performed to obtain the proper mesh number. First, the mechanism of vortex cooling is further discussed, and the pronounced impact of kinetic turbulence intensity, thin thermal boundary layer, violent radial convection and complex vortices on enhanced heat transfer performance is confirmed. Then, seven jet nozzle aspect ratios and seven jet nozzle to chamber cross section area ratios are selected to research the flow field and thermal characteristics of vortex cooling focusing on the streamline, static pressure ratio, total pressure loss ratio and Nusselt number. It is presented that the jet nozzle aspect ratio and jet nozzle to chamber cross section area ratio both impose a significant effect on the flow and thermal parameters. The averaged Nusselt number decreases at first and then increases with the increasing jet nozzle aspect ratio, reaching highest when aspect ratio equals to 1. The effect of area ratio on averaged Nusselt number is complex. Finally, the heat transfer results in this study are compared with other previous works. Results indicate that good agreement with previous data is achieved, and the enhanced thermal behavior may be acquired by

  17. A CFD model for the IEA-R1 reactor neat exchanger inlet nozzle flow

    International Nuclear Information System (INIS)

    Andrade, Delvonei A.; Angelo, Gabriel; Gainer, Gerson; Angelo, Edvaldo; Umbehaun, Pedro E.; Torres, Walmir M.; Sabundjian, Gaiane; Macedo, Luiz A.; Belchior Junior, Antonio; Conti, Thadeu N.; Watanabe, Bruno C.; Sakai, Caio C.

    2011-01-01

    A previous preliminary model of the IEA-R1 heat exchanger inlet nozzle flow was developed and published in the International Nuclear Atlantic Conference-INAC-2009. A new model was created based on the preliminary one. It was improved concerning the actual heat exchanger tube bundle geometry. This became a very special issue. Difficulties with the size of the numerical mesh came out pointing to our computational system limits. New CFD calculations with this improved model were performed using ANSYS-CFX. In this paper, we present this model and discuss the results. (author)

  18. A CFD model for the IEA-R1 reactor neat exchanger inlet nozzle flow

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Delvonei A.; Angelo, Gabriel; Gainer, Gerson; Angelo, Edvaldo; Umbehaun, Pedro E.; Torres, Walmir M.; Sabundjian, Gaiane; Macedo, Luiz A.; Belchior Junior, Antonio; Conti, Thadeu N.; Watanabe, Bruno C.; Sakai, Caio C., E-mail: delvonei@ipen.b, E-mail: gfainer@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    A previous preliminary model of the IEA-R1 heat exchanger inlet nozzle flow was developed and published in the International Nuclear Atlantic Conference-INAC-2009. A new model was created based on the preliminary one. It was improved concerning the actual heat exchanger tube bundle geometry. This became a very special issue. Difficulties with the size of the numerical mesh came out pointing to our computational system limits. New CFD calculations with this improved model were performed using ANSYS-CFX. In this paper, we present this model and discuss the results. (author)

  19. Numerical Simulation of Non-Equilibrium Two-Phase Wet Steam Flow through an Asymmetric Nozzle

    Directory of Open Access Journals (Sweden)

    Miah Md Ashraful Alam

    2017-11-01

    Full Text Available The present study reported of the numerical investigation of a high-speed wet steam flow through an asymmetric nozzle. The spontaneous non-equilibrium homogeneous condensation of wet steam was numerically modeled based on the classical nucleation theory and droplet growth rate equation combined with the field conservations within the computational fluid dynamics (CFD code of ANSYS Fluent 13.0. The equations describing droplet formations and interphase change were solved sequentially after solving the main flow conservation equations. The calculations were carried out assuming the flow two-dimensional, compressible, turbulent, and viscous. The SST k-ω model was used for modeling the turbulence within an unstructured mesh solver. The validation of numerical model was accomplished, and the results showed a good agreement between the numerical simulation and experimental data. The effect of spontaneous non-equilibrium condensation on the jet and shock structures was revealed, and the condensation shown a great influence on the jet structure.

  20. Experimental study of micron size droplets in a two phase flow in a converging - diverging nozzle

    International Nuclear Information System (INIS)

    Jurski, Kristine

    1997-01-01

    The fluid present in a pressurized vessel in normal operation is generally a mono-phase one. In accidental regime (a breach for example), a two-phase (ring and/or dispersed) flow appears and the flow is submitted to large accelerations when passing through the breach, and is then dispersed in the atmosphere. This research thesis reports an experimental simulation of an accident by generating, through a discharge of an upstream vessel into a downstream vessel, a strongly accelerated gaseous-liquid two-phase flow, with an essentially dispersed configuration in a convergent-divergent nozzle. In order to characterize the speed and diameter evolution of the dispersed liquid phase, the author reports a comparative study of two different liquid aerosols: micron-size droplets of di-octyl phthalate (DOP) of known concentration and diameter, and water droplets obtained by heterogeneous spontaneous condensation [fr

  1. Highly stabilized partially premixed flames of propane in a concentric flow conical nozzle burner with coflow

    KAUST Repository

    Elbaz, Ayman M.

    2018-01-11

    Partially premixed turbulent flames with non-homogeneous jet of propane were generated in a concentric flow conical nozzle burner in order to investigate the effect of the coflow on the stability and flame structure. The flame stability is first mapped and then high-speed stereoscopic particle image velocimetry, SPIV, plus OH planar laser-induced fluorescence, OH-PLIF, measurements were conducted on a subset of four flames. The jet equivalence ratio Φ = 2, Jet exit Reynolds number Re = 10,000, and degree of premixing are kept constant for the selected flames, while the coflow velocity, Uc, is progressively changed from 0 to 15 m/s. The results showed that the flame is stable between two extinction limits of mixture inhomogeneity, and the optimum stability is obtained at certain degree of mixture inhomogeneity. Increasing Φ, increases the span between these two extinction limits, while these limits converge to a single point (corresponding to optimum mixture inhomogeneity) with increasing Re. Regardless the value of Φ, increasing the coflow velocity improves the flame stability. The correlation between recessed distance of the burner tubes and the fluctuation of the mixture fraction, Δξ, shows that at Δξ around 40% of the flammability limits leads to optimum flame stability. The time averaged SPIV results show that the coflow induces a big annular recirculation zone surrounds the jet flames. The size and the location of this zone is seen to be sensitive to Uc. However, the instantaneous images show the existence of a small vortical structure close to the shear layer, where the flame resides there in the case of no-coflow. These small vertical structures are seen playing a vital role in the flame structure, and increasing the flame corrugation close to the nozzle exit. Increasing the coflow velocity expands the central jet at the expense of the jet velocity, and drags the flame in the early flame regions towards the recirculation zone, where the flame tracks

  2. Large-eddy simulation of cavitating nozzle flow and primary jet break-up

    Energy Technology Data Exchange (ETDEWEB)

    Örley, F., E-mail: felix.oerley@aer.mw.tum.de; Trummler, T.; Mihatsch, M. S.; Schmidt, S. J.; Adams, N. A. [Institute of Aerodynamics and Fluid Mechanics, Technische Universität München, Boltzmannstr. 15, 85748 Garching bei München (Germany); Hickel, S. [Institute of Aerodynamics and Fluid Mechanics, Technische Universität München, Boltzmannstr. 15, 85748 Garching bei München (Germany); Chair of Computational Aerodynamics, Faculty of Aerospace Engineering, TU Delft, Kluyverweg 1, 2629 HS Delft (Netherlands)

    2015-08-15

    We employ a barotropic two-phase/two-fluid model to study the primary break-up of cavitating liquid jets emanating from a rectangular nozzle, which resembles a high aspect-ratio slot flow. All components (i.e., gas, liquid, and vapor) are represented by a homogeneous mixture approach. The cavitating fluid model is based on a thermodynamic-equilibrium assumption. Compressibility of all phases enables full resolution of collapse-induced pressure wave dynamics. The thermodynamic model is embedded into an implicit large-eddy simulation (LES) environment. The considered configuration follows the general setup of a reference experiment and is a generic reproduction of a scaled-up fuel injector or control valve as found in an automotive engine. Due to the experimental conditions, it operates, however, at significantly lower pressures. LES results are compared to the experimental reference for validation. Three different operating points are studied, which differ in terms of the development of cavitation regions and the jet break-up characteristics. Observed differences between experimental and numerical data in some of the investigated cases can be caused by uncertainties in meeting nominal parameters by the experiment. The investigation reveals that three main mechanisms promote primary jet break-up: collapse-induced turbulent fluctuations near the outlet, entrainment of free gas into the nozzle, and collapse events inside the jet near the liquid-gas interface.

  3. Droplet size and velocity at the exit of a nozzle with two-component near critical and critical flow

    International Nuclear Information System (INIS)

    Lemonnier, H.; Camelo-Cavalcanti, E.S.

    1993-01-01

    Two-component critical flow modelling is an important issue for safety studies of various hazardous industrial activities. When the flow quality is high, the critical flow rate prediction is sensitive to the modelling of gas droplet mixture interfacial area. In order to improve the description of these flows, experiments were conducted with air-water flows in converging nozzles. The pressure was 2 and 4 bar and the gas mass quality ranged between 100% and 20%. The droplets size and velocity have been measured close to the outlet section of a nozzle with a 10 mm diameter throat. Subcritical and critical conditions were observed. These data are compared with the predictions of a critical flow model which includes an interfacial area model based on the classical ideas of Hinze and Kolmogorov. (authors). 9 figs., 12 refs

  4. Base Flow and Heat Transfer Characteristics of a Four-Nozzle Clustered Rocket Engine: Effect of Nozzle Pressure Ratio

    Science.gov (United States)

    Nallasamy, R.; Kandula, M.; Duncil, L.; Schallhorn, P.

    2010-01-01

    The base pressure and heating characteristics of a four-nozzle clustered rocket configuration is studied numerically with the aid of OVERFLOW Navier-Stokes code. A pressure ratio (chamber pressure to freestream static pressure) range of 990 to 5,920 and a freestream Mach number range of 2.5 to 3.5 are studied. The qualitative trends of decreasing base pressure with increasing pressure ratio and increasing base heat flux with increasing pressure ratio are correctly predicted. However, the predictions for base pressure and base heat flux show deviations from the wind tunnel data. The differences in absolute values between the computation and the data are attributed to factors such as perfect gas (thermally and calorically perfect) assumption, turbulence model inaccuracies in the simulation, and lack of grid adaptation.

  5. System and method having multi-tube fuel nozzle with differential flow

    Science.gov (United States)

    Hughes, Michael John; Johnson, Thomas Edward; Berry, Jonathan Dwight; York, William David

    2017-01-03

    A system includes a multi-tube fuel nozzle with a fuel nozzle body and a plurality of tubes. The fuel nozzle body includes a nozzle wall surrounding a chamber. The plurality of tubes extend through the chamber, wherein each tube of the plurality of tubes includes an air intake portion, a fuel intake portion, and an air-fuel mixture outlet portion. The multi-tube fuel nozzle also includes a differential configuration of the air intake portions among the plurality of tubes.

  6. Molecular dynamics study of Ar flow and He flow inside carbon nanotube junction as a molecular nozzle and diffuser

    Directory of Open Access Journals (Sweden)

    Itsuo Hanasaki, Akihiro Nakatani and Hiroshi Kitagawa

    2004-01-01

    Full Text Available A carbon nanotube junction consists of two connected nanotubes with different diameters. It has been extensively investigated as a molecular electronic device since carbon nanotubes can be metallic and semiconductive, depending on their structure. However, a carbon nanotube junction can also be viewed as a nanoscale nozzle andv diffuser. Here, we focus on the nanotube junction from the perspective of an intersection between machine, material and device. We have conducted a molecular dynamics simulation of the molecular flow inside a modeled (12,12–(8,8 nanotube junction. A strong gravitational field and a periodic boundary condition are applied in the flow direction. We investigated dense-Ar flows and dense-He flows while controlling the temperature of the nanotube junction. The results show that Ar atoms tend to be near to the wall and the density of the Ar is higher in the wide (12,12 nanotube than in the narrow (8,8 nanotube, while it is lower in the wide tube when no flow occurs. The streaming velocities of both the Ar and the He are higher in the narrow nanotube than in the wide nanotube, but the velocity of the Ar is higher than the velocity of the He and the temperature of the flowing Ar is higher than the temperature of the He when the same magnitude of gravitational field is applied.

  7. Effect of the mixing fields on the stability and structure of turbulent partially premixed flames in a concentric flow conical nozzle burner

    KAUST Repository

    Mansour, Mohy S.; Elbaz, Ayman M.; Roberts, William L.; Senosy, Mohamed S.; Zayed, Mohamed F.; Juddoo, Mrinal; Masri, Assaad R.

    2016-01-01

    of partially premixed methane flames. The mixing field in a concentric flow conical nozzle (CFCN) burner with well-controlled mechanism of the mixing is investigated using Rayleigh scattering technique. The flame stability, structure and flow field of some

  8. Internal Nozzle Flow Simulations of Gasoline-Like Fuels under Diesel Operating Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Torelli, R.; Som, S.; Pei, Y.; Zhang, Yu; Traver, Michael

    2017-05-15

    Spray formation in internal combustion engines with direct injection is strictly correlated with internal nozzle flow characteristics, which are in turn influenced by fuel physical properties and injector needle motion. This paper pre-sents a series of 3D simulations that model the in-nozzle flow in a 5-hole mini-sac diesel injector. Two gasoline-like naphtha fuels, namely full-range and light naphtha, were tested under operating conditions typical of diesel applica-tions and were compared with n-dodecane, selected from a palette used as diesel surrogates. Validated methodolo-gies from our previous work were employed to account for realistic needle motion. The multi-phase nature of the problem was described by the mixture model assumption with the Volume of Fluid method. Cavitation effects were included by means of the Homogeneous Relaxation Model and turbulence closure was achieved with the Standard k-ε model in an Unsteady Reynolds-Averaged Navier-Stokes formulation. The results revealed that injector perfor-mance and propensity to cavitation are influenced by the fuel properties. Analyses of several physical quantities were carried out to highlight the fuel-to-fuel differences in terms of mass flow rate, discharge coefficients, and fuel vapor volume fraction inside the orifices. A series of parametric investigations was also performed to assess the fuel response to varied fuel injection temperature, injection pressure, and cross-sectional orifice area. For all cases, the strict correlation between cavitation magnitude and saturation pressure was confirmed. Owing to their higher volatil-ity, the two gasoline-like fuels were characterized by higher cavitation across all the simulated conditions. Occur-rence of cavitation was mostly found at the needle seat and at the orifice inlets during the injection event’s transient, when very small gaps exist between the needle and its seat. This behavior tended to disappear at maximum needle lift, where cavitation was

  9. Flow characteristics and heat transfer performances of a semi-confined impinging array of jets: effect of nozzle geometry

    Energy Technology Data Exchange (ETDEWEB)

    Dano, B.P.E.; Liburdy, J.A. [Oregon State Univ., Corvallis, OR (United States). Dept. of Mechanical Engineering; Kanokjaruvijit, Koonlaya [Imperial College, London (United Kingdom). Dept. of Mechanical Engineering

    2005-02-01

    The flow and heat transfer characteristics of confined jet array impingement with crossflow is investigated. Discrete impingement pressure measurements are used to obtain the jet orifice discharge flow coefficient. Digital particle image velocimetry (DPIV) and flow visualization are used to determine the flow characteristics. Two thermal boundary conditions at the impinging surface are presented: an isothermal surface, and a uniform heat flux, where thermocouple and thermochromic liquid crystal methods were used, respectively, to determine the local heat transfer coefficient. Two nozzle geometries are studied, circular and cusped ellipse. Based on the interaction with the jet impingement at the surface, the crossflow is shown to influence the heat transfer results. The two thermal boundary conditions differ in overall heat transfer correlation with the jet Reynolds number. Detailed velocity data show that the flow development from the cusped ellipse nozzle affects the wall region flow more than the circular nozzle, as influenced by the crossflow interactions. The overall heat transfer for the uniform heat flux boundary condition is found to increase for the cusped ellipse orifice. (Author)

  10. A study on nozzle flow and spray characteristics of piezo injector for next generation high response injection

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Wook [Korea Institue of Machinery and Materials, Daejeon (Korea, Republic of); Min, Kyoung Doug [Seoul National University, Seoul (Korea, Republic of)

    2006-06-15

    Most diesel injector, which is currently used in high-pressure common rail fuel injection system of diesel engine, is driven by the solenoid coil energy for its needle movement. The main disadvantage of this solenoid-driven injector is a high power consumption, high power loss through solenoid coil and relatively fixed needle response's problem. In this study, a prototype piezo-driven injector, as a new injector mechanism driven by piezoelectric energy based on the concept of inverse piezo-electric effect, has been designed and fabricated to know the effect of piezo-driven injection processes on the diesel spray structure and internal nozzle flow. Firstly we investigated the spray characteristics in a constant volume chamber pressurized by nitrogen gas using the back diffusion light illumination method for high-speed temporal photography and also analyzed the inside nozzle flow by a fully transient simulation with cavitation model using VOF(Volume Of Fraction) method. The numerical calculation has been performed to simulate the cavitating flow of 3-dimensional real size single hole nozzle along the injection duration. Results were compared between a conventional solenoid-driven injector and piezo-driven injector, both equipped with the same micro-sac multi-hole injection nozzle. The experimental results show that the piezo-driven injector has short injection delay and a faster spray development and produces higher injection velocity than the solenoid-driven injector. And the predicted simulation results with the degree of cavitation's generation inside nozzle for faster needle response in a piezo-driven injector were reflected to spray development in agreement with the experimental spray images.

  11. A study on nozzle flow and spray characteristics of piezo injector for next generation high response injection

    International Nuclear Information System (INIS)

    Lee, Jin Wook; Min, Kyoung Doug

    2006-01-01

    Most diesel injector, which is currently used in high-pressure common rail fuel injection system of diesel engine, is driven by the solenoid coil energy for its needle movement. The main disadvantage of this solenoid-driven injector is a high power consumption, high power loss through solenoid coil and relatively fixed needle response's problem. In this study, a prototype piezo-driven injector, as a new injector mechanism driven by piezoelectric energy based on the concept of inverse piezo-electric effect, has been designed and fabricated to know the effect of piezo-driven injection processes on the diesel spray structure and internal nozzle flow. Firstly we investigated the spray characteristics in a constant volume chamber pressurized by nitrogen gas using the back diffusion light illumination method for high-speed temporal photography and also analyzed the inside nozzle flow by a fully transient simulation with cavitation model using VOF(Volume Of Fraction) method. The numerical calculation has been performed to simulate the cavitating flow of 3-dimensional real size single hole nozzle along the injection duration. Results were compared between a conventional solenoid-driven injector and piezo-driven injector, both equipped with the same micro-sac multi-hole injection nozzle. The experimental results show that the piezo-driven injector has short injection delay and a faster spray development and produces higher injection velocity than the solenoid-driven injector. And the predicted simulation results with the degree of cavitation's generation inside nozzle for faster needle response in a piezo-driven injector were reflected to spray development in agreement with the experimental spray images

  12. Chevron closing base wedge bunionectomy.

    Science.gov (United States)

    Bruyn, J M

    1993-01-01

    The Chevron-base wedge Association for Osteosynthesis fixated bunionectomy provides a stable, aggressive correction of the severe hallux abducto valgus deformity. It is intended for the bunion requiring a double osteotomy in order to adequately reduce both intermetatarsal and proximal articular facet angle with minimal shortening and elevation. This article presents the rationale for the procedure, technique, and a 4-year follow-up of six patients with eight Chevron-base wedge bunionectomies.

  13. Numerical Investigation on Aerodynamic and Combustion Performance of Chevron Mixer Inside an Afterburner.

    Science.gov (United States)

    Yong, Shan; JingZhou, Zhang; Yameng, Wang

    2014-11-01

    To improve the performance of the afterburner for the turbofan engine, an innovative type of mixer, namely, the chevron mixer, was considered to enhance the mixture between the core flow and the bypass flow. Computational fluid dynamics (CFD) simulations investigated the aerodynamic performances and combustion characteristics of the chevron mixer inside a typical afterburner. Three types of mixer, namely, CC (chevrons tilted into core flow), CB (chevrons tilted into bypass flow), and CA (chevrons tilted into core flow and bypass flow alternately), respectively, were studied on the aerodynamic performances of mixing process. The chevrons arrangement has significant effect on the mixing characteristics and the CA mode seems to be advantageous for the generation of the stronger streamwise vortices with lower aerodynamic loss. Further investigations on combustion characteristics for CA mode were performed. Calculation results reveal that the local temperature distribution at the leading edge section of flame holder is improved under the action of streamwise vortices shedding from chevron mixers. Consequently, the combustion efficiency increased by 3.5% compared with confluent mixer under the same fuel supply scheme.

  14. The use of nested chevron rails in a distributed energy store railgun

    Science.gov (United States)

    Marshall, R. A.

    1984-03-01

    It is pointed out that the large amounts of energy required by electromagnetic launchers will necessitate that energy stores be distributed along their length. The nested chevron rail construction will make it possible for a railgun launcher to be produced in which most of the switching requirements for the launcher/energy store system will be met automatically. Each nested chevron-shaped conductor will be electrically insulated from its neighbors, and each opposing chevron pair (one on each rail) will be connected to the terminals of one energy store (Marshall, 1982). It is explained that as the projectile moves down the railgun the chevrons and associated energy stores at first are unaffected by the approach. At this time the inductors can be charged, and any other preliminary operation can be performed. When the armature comes into contact with the Nth chevron, charge begins to flow from the Nth energy storage system; it flows through one chevron, into the armature, out of the armature into the other chevron, and from that chevron back to the energy storage system.

  15. Firefighter Nozzle Reaction

    DEFF Research Database (Denmark)

    Chin, Selena K.; Sunderland, Peter B.; Jomaas, Grunde

    2017-01-01

    to anchor forces, the hose becomes straight. The nozzle reaction is found to equal the jet momentum flow rate, and it does not change when an elbow connects the hose to the nozzle. A forward force must be exerted by a firefighter or another anchor that matches the forward force that the jet would exert...... on a perpendicular wall. Three reaction expressions are derived, allowing it to be determined in terms of hose diameter, jet diameter, flow rate, and static pressure upstream of the nozzle. The nozzle reaction predictions used by the fire service are 56% to 90% of those obtained here for typical firefighting hand...

  16. Effect of Orifice Nozzle Design and Input Power on Two-Phase Flow and Mass Transfer Characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hei Cheon [Chonnam Nat’l Univ., Gwangju (Korea, Republic of)

    2016-04-15

    It is necessary to investigate the input power as well as the mass transfer characteristics of the aeration process in order to improve the energy efficiency of an aerobic water treatment. The objective of this study is to experimentally investigate the effect of orifice nozzle design and input power on the flow and mass transfer characteristics of a vertical two-phase flow. The mass ratio, input power, volumetric mass transfer coefficient, and mass transfer efficiency were calculated using the measured data. It was found that as the input power increases the volumetric mass transfer coefficient increases, while the mass ratio and mass transfer efficiency decrease. The mass ratio, volumetric mass transfer coefficient, and mass transfer efficiency were higher for the orifice configuration with a smaller orifice nozzle area ratio. An empirical correlation was proposed to estimate the effect of mass ratio, input power, and Froude number on the volumetric mass transfer coefficient.

  17. Behaviour of a pressure vessel nozzle with thermo-sleeve under thermal loading induced by stratified flow

    International Nuclear Information System (INIS)

    Kussmaul, K.; Mayinger, W.; Diem, H.; Katzenmeier, G.

    1993-01-01

    Startup at low reactor power may give rise to stratified flow conditions in pipes of boiling water and pressurized water reactors. Stratified flow regimes cause a steep temperature gradient between the cold and the hot fluid layer. This temperature gradient produces high axial stresses which, in the case of intermittent feeding of cold water and an appropriate number of repetitions, in principle may initiate cracking in the feedwater pipe and close to the feeding nozzle. Thermosleeves have been installed in a number of reactors to mitigate thermally induced stresses; they reduce the intensity of thermal transients by means of an insulating fluid annulus developing between the sleeve and the nozzle, in order to measure the temperature and stress gradients occurring in the region of the nozzle edge, the so-called TEMS experiments were carried out under realistic operating conditions, and with different cold water levels within the framework of German research activities in the field of reactor safety at the HDR test facility. The experiments served to simulate the physics phenomena by means of a FE-program and to verify the computational approach by comparisons of measurements and calculations

  18. Altitude Compensating Nozzle

    Science.gov (United States)

    Ruf, Joseph H.; Jones, Daniel

    2015-01-01

    The dual-bell nozzle (fig. 1) is an altitude-compensating nozzle that has an inner contour consisting of two overlapped bells. At low altitudes, the dual-bell nozzle operates in mode 1, only utilizing the smaller, first bell of the nozzle. In mode 1, the nozzle flow separates from the wall at the inflection point between the two bell contours. As the vehicle reaches higher altitudes, the dual-bell nozzle flow transitions to mode 2, to flow full into the second, larger bell. This dual-mode operation allows near optimal expansion at two altitudes, enabling a higher mission average specific impulse (Isp) relative to that of a conventional, single-bell nozzle. Dual-bell nozzles have been studied analytically and subscale nozzle tests have been completed.1 This higher mission averaged Isp can provide up to a 5% increase2 in payload to orbit for existing launch vehicles. The next important step for the dual-bell nozzle is to confirm its potential in a relevant flight environment. Toward this end, NASA Marshall Space Flight Center (MSFC) and Armstrong Flight Research Center (AFRC) have been working to develop a subscale, hot-fire, dual-bell nozzle test article for flight testing on AFRC's F15-D flight test bed (figs. 2 and 3). Flight test data demonstrating a dual-bell ability to control the mode transition and result in a sufficient increase in a rocket's mission averaged Isp should help convince the launch service providers that the dual-bell nozzle would provide a return on the required investment to bring a dual-bell into flight operation. The Game Changing Department provided 0.2 FTE to ER42 for this effort in 2014.

  19. Pitot pressure measurements in flow fields behind circular-arc nozzles with exhaust jets at subsonic free-stream Mach numbers. [langley 16 foot transonic tunnel

    Science.gov (United States)

    Mason, M. L.; Putnam, L. E.

    1979-01-01

    The flow field behind a circular arc nozzle with exhaust jet was studied at subsonic free stream Mach numbers. A conical probe was used to measure the pitot pressure in the jet and free stream regions. Pressure data were recorded for two nozzle configurations at nozzle pressure ratios of 2.0, 2.9, and 5.0. At each set of test conditions, the probe was traversed from the jet center line into the free stream region at seven data acquisition stations. The survey began at the nozzle exit and extended downstream at intervals. The pitot pressure data may be applied to the evaluation of computational flow field models, as illustrated by a comparison of the flow field data with results of inviscid jet plume theory.

  20. Firefighter Nozzle Reaction

    DEFF Research Database (Denmark)

    Chin, Selena K.; Sunderland, Peter B.; Jomaas, Grunde

    2017-01-01

    Nozzle reaction and hose tension are analyzed using conservation of fluid momentum and assuming steady, inviscid flow and a flexible hose in frictionless contact with the ground. An expression that is independent of the bend angle is derived for the hose tension. If this tension is exceeded owing...... to anchor forces, the hose becomes straight. The nozzle reaction is found to equal the jet momentum flow rate, and it does not change when an elbow connects the hose to the nozzle. A forward force must be exerted by a firefighter or another anchor that matches the forward force that the jet would exert...... on a perpendicular wall. Three reaction expressions are derived, allowing it to be determined in terms of hose diameter, jet diameter, flow rate, and static pressure upstream of the nozzle. The nozzle reaction predictions used by the fire service are 56% to 90% of those obtained here for typical firefighting hand...

  1. Simulation of a flow spontaneously condensed moist steam in Laval nozzles

    International Nuclear Information System (INIS)

    Avetisyan, A.R.; Alipchenkov, V.M.; Zajchik, L.I.

    2002-01-01

    The method for simulating the evolution of the drops distribution by size in the course of commonly proceeding processes of nucleation (spontaneous condensation), heterogeneous condensation) evaporation and coagulation is proposed. The results of the analysis of the initial moisture effect on the steam spontaneous condensation in the transonic nozzles are presented. The availability of the minima in the output moisture dependences on the drops initial moisture and size is the most interesting result of the initial moisture effect on the spontaneous condensation in the Laval nozzles [ru

  2. Pennzoil to acquire part of Chevron's production

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This paper reports that Pennzoil Co., Houston, will exchange 48% of its $2.2 billion investment in Chevron Corp. for a chunk of chevron's U.S. producing leases. The trade is to involve a tax free exchange of 15.75 million chevron Corp. shares held by Pennzoil for all the stock of Chevron PBC Inc., a Chevron unit owning Gulf of Mexico, Gulf Coast, Permian basin, and other U.S. oil and gas producing leases. Sixty percent of the acquired reserves are in the Gulf of Mexico and Gulf Coast where Pennzoil's operations are concentrated, and 60% of the acquired reserves consist of natural gas, mirroring Pennzoil's reserve ratios

  3. An analysis of the shielding gas flow from a coaxial conical nozzle during high power CO2 laser welding

    International Nuclear Information System (INIS)

    Ancona, Antonio; Sibillano, Teresa; Lugara, Pietro Mario; Gonnella, Giuseppe; Pascazio, Giuseppe; Maffione, Donato

    2006-01-01

    An experimental and theoretical study on the role of the nitrogen gas stream, exiting from a conventional conical nozzle tip during a laser welding process, has been carried out. A mathematical model has been used, based on the Navier-Stokes equations which express fundamental conservation laws of mass, momentum and energy for a compressible fluid. Numerical simulations of the gas stream colliding onto a plane surface have been performed showing the effects of variations of inlet gas pressure, nozzle exit diameter and standoff distance on the density and Mach number contours, axis pressure of the gas jet and plate pressure produced on the workpiece surface. Laser welding experiments have been performed on carbon and stainless steel specimens, by varying the process parameters in the same range as in the simulations and keeping constant the incident power and the travel speed. Two different gas stream regimes were found, namely sonic and subsonic, which were experimentally verified to produce cutting and welding conditions, respectively. Weld performances have been evaluated in terms of bead width, penetration depth and melted area. Nozzle standoff distance was found to have a negligible influence, while the exit diameter and the flow rate significantly affect the weld results. The numerical predictions allowed an explanation of the experimental results yielding useful suggestions for enhancing the weld quality, acting simply on the shielding gas parameters

  4. Influence of Fluid–Thermal–Structural Interaction on Boundary Layer Flow in Rectangular Supersonic Nozzles

    Directory of Open Access Journals (Sweden)

    Kalyani Bhide

    2018-03-01

    Full Text Available The aim of this work is to highlight the significance of Fluid–Thermal–Structural Interaction (FTSI as a diagnosis of existing designs, and as a means of preliminary investigation to ensure the feasibility of new designs before conducting experimental and field tests. The novelty of this work lies in the multi-physics simulations, which are, for the first time, performed on rectangular nozzles. An existing experimental supersonic rectangular converging/diverging nozzle geometry is considered for multi-physics 3D simulations. A design that has been improved by eliminating the sharp throat is further investigated to evaluate its structural integrity at design Nozzle Pressure Ratio (NPR 3.67 and off-design (NPR 4.5 conditions. Static structural analysis is performed by unidirectional coupling of pressure loads from steady 3D Computational Fluid Dynamics (CFD and thermal loads from steady thermal conduction simulations, such that the simulations represent the experimental set up. Structural deformation in the existing design is far less than the boundary layer thickness, because the impact of Shock wave Boundary Layer Interaction (SBLI is not as severe. FTSI demonstrates that the discharge coefficient of the improved design is 0.99, and its structural integrity remains intact at off-design conditions. This proves the feasibility of the improved design. Although FTSI influence is shown for a nozzle, the approach can be applied to any product design cycle, or as a prelude to building prototypes.

  5. Analysis of Flow Evolution and Thermal Instabilities in the Near-Nozzle Region of a Free Plane Laminar Jet

    Directory of Open Access Journals (Sweden)

    Hector Barrios-Piña

    2015-01-01

    Full Text Available This work focuses on the evolution of a free plane laminar jet in the near-nozzle region. The jet is buoyant because it is driven by a continuous addition of both buoyancy and momentum at the source. Buoyancy is given by a temperature difference between the jet and the environment. To study the jet evolution, numerical simulations were performed for two Richardson numbers: the one corresponding to a temperature difference slightly near the validity of the Boussinesq approximation and the other one corresponding to a higher temperature difference. For this purpose, a time dependent numerical model is used to solve the fully dimensional Navier-Stokes equations. Density variations are given by the ideal gas law and flow properties as dynamic viscosity and thermal conductivity are considered nonconstant. Particular attention was paid to the implementation of the boundary conditions to ensure jet stability and flow rates control. The numerical simulations were also reproduced by using the Boussinesq approximation to find out more about its pertinence for this kind of flows. Finally, a stability diagram is also obtained to identify the onset of the unsteady state in the near-nozzle region by varying control parameters of momentum and buoyancy. It is found that, at the onset of the unsteady state, momentum effects decrease almost linearly when buoyancy effects increase.

  6. Investigation of a two-phase nozzle flow and validation of several computer codes by the experimental data

    International Nuclear Information System (INIS)

    Kedziur, F.

    1980-03-01

    Stationary experiments with a convergent nozzle are performed in order to validate advanced two-phase computer codes, which find application in the blowdown-phase of a loss-of-coolant accident (LOCA). The steam/water flow presents a broad variety of initial conditions: The pressure varies between 2 and 13 MPa, the void fraction between 0 (subcooled) and about 80%, a great number of subcritical as well as critical experiments with different flow pattern is investigated. Additional air/water experiments serve for the separation of phase transition effects. The transient acceleration of the fluid in the LOCA-case is simulated by a local acceleration in the experiments. The layout of the nozzle and the applied measurement technique allow for a separate testing of physical models and the determination of empirical model parameters, respectively: In the four codes DUESE, DRIX-20, RELAP4/MOD6 and STRUYA the models - if they exist - for slip between the phases, thermodynamic non-equilibrium, pipe friction and critical mass flow rate are validated and criticised in comparison with the experimental data, and the corresponding model parameters are determined. The parameters essentially are a function of the void fraction. (orig.) [de

  7. Investigation the effects of injection pressure and compressibility and nozzle entry in diesel injector nozzle’s flow

    Directory of Open Access Journals (Sweden)

    Seyed mohammadjavad Zeidi

    2015-04-01

    Full Text Available Investigating nozzle’s orifice flow is challenging both experimentally and theoretically. This paper focuses on simulating flow inside diesel injector nozzle via Ansys fluent v15. Validation is performed with experimental results from Winkhofler et al (2001. Several important parameters such as mass flow rate, velocity profiles and pressure profiles are used for this validation. Results include the effects of contraction inside nozzle’s orifice, effect of compressibility; effect of injection pressures and several orifice entries are also simulated in this study. For considering the effect of compressibility a user defined function used in this simulation. Cavitation model which is used in this simulation is Singhal et al. cavitation model. Presto discretization method is used for Pressure equation and second upwind discretization method is used for Momentum equation. Converging Singhal et al. cavitation model is very challenging and it needs several efforts and simulations.

  8. Transition of cavitating flow to supercavitation within Venturi nozzle – hysteresis investigation

    OpenAIRE

    Jiří Kozák; Pavel Rudolf; Rostislav Huzlík; Martin Hudec; Radomír Chovanec; Ondřej Urban; Blahoslav Maršálek; Eliška Maršálková; František Pochylý; David Štefan

    2017-01-01

    Cavitation is usually considered as undesirable phenomena. On the other hand, it can be utilized in many applications. One of the technical applications is using cavitation in water treatment, where hydrodynamic cavitation seems to be effective way how to reduce cyanobacteria within large bulks of water. The main scope of this paper is investigation of the cavitation within Venturi nozzle during the transition from fully developed cavitation to supercavitation regime and vice versa. Dynamics ...

  9. Cold water injection nozzles

    International Nuclear Information System (INIS)

    Kura, Masaaki; Maeda, Masamitsu; Endo, Takio.

    1979-01-01

    Purpose: To inject cold water in a reactor without applying heat cycles to a reactor container and to the inner wall of a feedwater nozzle by securing a perforated plate at the outlet of the cold water injection nozzle. Constitution: A disc-like cap is secured to the final end of a return nozzle of a control rod drive. The cap prevents the flow of a high temperature water flowing downward in the reactor from entering into the nozzle. The cap is perforated with a plurality of bore holes for injecting cold water into the reactor. The cap is made to about 100 mm in thickness so that the cold water passing through the bore holes is heated by the heat conduction in the cap. Accordingly, the flow of high temperature water flowing downwardly in the reactor is inhibited by the cap from backward flowing into the nozzle. Moreover, the flow of the cold water in the nozzle is controlled and rectified when passed through the bore holes in the cap and then injected into the reactor. (Yoshino, Y.)

  10. Influence of transit water flow rate on its dispensation and on inflow through nozzles in pressure pipeline under action of external pressure

    Science.gov (United States)

    Cherniuk, V. V.; Riabenko, O. A.; Ivaniv, V. V.

    2017-12-01

    The influence of transit flow rate of water upon operative of the equipped with nozzles pressure pipeline is experimentally investigated. External pressure, which varies in the range of 1465-2295 mm, acted upon the pipeline. The angle β between vectors of velocities of the stream in the pipeline and jets which branch off through nozzles were given the value: 0° ; 45° ; 90° ; 135° ; 180°. The diameter of the pipeline was of D=20.18 mm, the diameter of nozzles d=6.01 mm. The distances between the nozzles were 180 mm, and the number of them 11. The value of the transit flow rate at input into the pipeline varied from 4.05 to 130.20 cm3 / s. The increase in flow rate of the transit flux Qtr caused increase in non-uniformity of distribution of operating heads and increase in flow rate of water along the pipeline over the segment of its dispensation. On the segment of collecting of water, inverse tendency was observed. The number of nozzles through which water became to be dispensed increased with the increase in Qtr.

  11. Numerical study of the SSME nozzle flow fields during transient operations: A comparison of the animated results with test

    Science.gov (United States)

    Wang, Ten-See; Dumas, Catherine

    1993-01-01

    A computational fluid dynamics (CFD) model has been applied to study the transient flow phenomena of the nozzle and exhaust plume of the Space Shuttle Main Engine (SSME), fired at sea level. The CFD model is a time accurate, pressure based, reactive flow solver. A six-species hydrogen/oxygen equilibrium chemistry is used to describe the chemical-thermodynamics. An adaptive upwinding scheme is employed for the spatial discretization, and a predictor, multiple corrector method is used for the temporal solution. Both engine start-up and shut-down processes were simulated. The elapse time is approximately five seconds for both cases. The computed results were animated and compared with the test. The images for the animation were created with PLOT3D and FAST and then animated with ABEKAS. The hysteresis effects, and the issues of free-shock separation, restricted-shock separation and the end-effects were addressed.

  12. A Study on the Nonmetallic Inclusion Motions in a Swirling Flow Submerged Entry Nozzle in a New Cylindrical Tundish Design

    Science.gov (United States)

    Ni, Peiyuan; Ersson, Mikael; Jonsson, Lage Tord Ingemar; Jönsson, Pär Göran

    2018-04-01

    Different sizes and shapes of nonmetallic inclusions in a swirling flow submerged entry nozzle (SEN) placed in a new tundish design were investigated by using a Lagrangian particle tracking scheme. The results show that inclusions in the current cylindrical tundish have difficulties remaining in the top tundish region, since a strong rotational steel flow exists in this region. This high rotational flow of 0.7 m/s provides the required momentum for the formation of a strong swirling flow inside the SEN. The results show that inclusions larger than 40 µm were found to deposit to a smaller extent on the SEN wall compared to smaller inclusions. The reason is that these large inclusions have Separation number values larger than 1. Thus, the swirling flow causes these large size inclusions to move toward the SEN center. For the nonspherical inclusions, large size inclusions were found to be deposited on the SEN wall to a larger extent, compared to spherical inclusions. More specifically, the difference of the deposited inclusion number is around 27 pct. Overall, it was found that the swirling flow contains three regions, namely, the isotropic core region, the anisotropic turbulence region and the near-wall region. Therefore, anisotropic turbulent fluctuations should be taken into account when the inclusion motion was tracked in this complex flow. In addition, many inclusions were found to deposit at the SEN inlet region. The plotted velocity distribution shows that the inlet flow is very chaotic. A high turbulent kinetic energy value of around 0.08 m2/s2 exists in this region, and a recirculating flow was also found here. These flow characteristics are harmful since they increase the inclusion transport toward the wall. Therefore, a new design of the SEN inlet should be developed in the future, with the aim to modify the inlet flow so that the inclusion deposition is reduced.

  13. Axisymmetric thrust-vectoring nozzle performance prediction

    International Nuclear Information System (INIS)

    Wilson, E. A.; Adler, D.; Bar-Yoseph, P.Z

    1998-01-01

    Throat-hinged geometrically variable converging-diverging thrust-vectoring nozzles directly affect the jet flow geometry and rotation angle at the nozzle exit as a function of the nozzle geometry, the nozzle pressure ratio and flight velocity. The consideration of nozzle divergence in the effective-geometric nozzle relation is theoretically considered here for the first time. In this study, an explicit calculation procedure is presented as a function of nozzle geometry at constant nozzle pressure ratio, zero velocity and altitude, and compared with experimental results in a civil thrust-vectoring scenario. This procedure may be used in dynamic thrust-vectoring nozzle design performance predictions or analysis for civil and military nozzles as well as in the definition of initial jet flow conditions in future numerical VSTOL/TV jet performance studies

  14. A Physical Model to Study the Effects of Nozzle Design on Dispersed Two-Phase Flows in a Slab Mold Casting Ultra-Low-Carbon Steels

    Science.gov (United States)

    Salazar-Campoy, María M.; Morales, R. D.; Nájera-Bastida, A.; Calderón-Ramos, Ismael; Cedillo-Hernández, Valentín; Delgado-Pureco, J. C.

    2018-04-01

    The effects of nozzle design on dispersed, two-phase flows of the steel-argon system in a slab mold are studied using a water-air model with particle image velocimetry and ultrasound probe velocimetry techniques. Three nozzle designs were tested with the same bore size and different port geometries, including square (S), special bottom design with square ports (U), and circular (C). The meniscus velocities of the liquid increase two- or threefold in two-phase flows regarding one-phase flows using low flow rates of the gas phase. This effect is due to the dragging effects on bubbles by the liquid jets forming two-way coupled flows. Liquid velocities (primary phase) along the narrow face of the mold also are higher for two-phase flows. Flows using nozzle U are less dependent on the effects of the secondary phase (air). The smallest bubble sizes are obtained using nozzle U, which confirms that bubble breakup is dependent on the strain rates of the fluid and dissipation of kinetic energy in the nozzle bottom and port edges. Through dimensionless analysis, it was found that the bubble sizes are inversely proportional to the dissipation rate of the turbulent kinetic energy, ɛ 0.4. A simple expression involving ɛ, surface tension, and density of metal is derived to scale up bubble sizes in water to bubble sizes in steel with different degrees of deoxidation. The validity of water-air models to study steel-argon flows is discussed. Prior works related with experiments to model argon bubbling in steel slab molds under nonwetting conditions are critically reviewed.

  15. Transition of cavitating flow to supercavitation within Venturi nozzle - hysteresis investigation

    Science.gov (United States)

    Jiří, Kozák; Pavel, Rudolf; Rostislav, Huzlík; Martin, Hudec; Radomír, Chovanec; Ondřej, Urban; Blahoslav, Maršálek; Eliška, Maršálková; František, Pochylý; David, Štefan

    Cavitation is usually considered as undesirable phenomena. On the other hand, it can be utilized in many applications. One of the technical applications is using cavitation in water treatment, where hydrodynamic cavitation seems to be effective way how to reduce cyanobacteria within large bulks of water. The main scope of this paper is investigation of the cavitation within Venturi nozzle during the transition from fully developed cavitation to supercavitation regime and vice versa. Dynamics of cavitation was investigated using experimental data of pressure pulsations and analysis of high speed videos, where FFT of the pixel intensity and Proper Orthogonal Decomposition (POD) of the records were done to identify dominant frequencies connected with the presence of cavitation. The methodology of the high speed (HS) records semiautomated analysis using the FFT was described. Obtained results were correlated and above that the possible presence of hysteresis was discussed.

  16. Transition of cavitating flow to supercavitation within Venturi nozzle – hysteresis investigation

    Directory of Open Access Journals (Sweden)

    Jiří Kozák

    2017-01-01

    Full Text Available Cavitation is usually considered as undesirable phenomena. On the other hand, it can be utilized in many applications. One of the technical applications is using cavitation in water treatment, where hydrodynamic cavitation seems to be effective way how to reduce cyanobacteria within large bulks of water. The main scope of this paper is investigation of the cavitation within Venturi nozzle during the transition from fully developed cavitation to supercavitation regime and vice versa. Dynamics of cavitation was investigated using experimental data of pressure pulsations and analysis of high speed videos, where FFT of the pixel intensity and Proper Orthogonal Decomposition (POD of the records were done to identify dominant frequencies connected with the presence of cavitation. The methodology of the high speed (HS records semiautomated analysis using the FFT was described. Obtained results were correlated and above that the possible presence of hysteresis was discussed.

  17. Nozzle geometry for organic vapor jet printing

    Science.gov (United States)

    Forrest, Stephen R.; McGraw, Gregory

    2017-10-25

    A first device is provided. The device includes a print head. The print head further includes a first nozzle hermetically sealed to a first source of gas. The first nozzle has an aperture having a smallest dimension of 0.5 to 500 microns in a direction perpendicular to a flow direction of the first nozzle. At a distance from the aperture into the first nozzle that is 5 times the smallest dimension of the aperture of the first nozzle, the smallest dimension perpendicular to the flow direction is at least twice the smallest dimension of the aperture of the first nozzle.

  18. Pitot-Pressure Measurements in Flow Fields Behind a Rectangular Nozzle with Exhaust Jet for Free-Stream Mach Numbers of 0.00, 0.60, and 1.20

    Science.gov (United States)

    Putnam, L. E.; Mercer, C. E.

    1986-01-01

    An investigation has been conducted in the Langley 16-Foot Transonic Tunnel to measure the flow field in and around the jet exhaust from a nonaxisymmetric nozzle configuration. The nozzle had a rectangular exit with a width-to-height ratio of 2.38. Pitot-pressure measurements were made at five longitudinal locations downstream of the nozzle exit. The maximum distance downstream of the exit was about 5 nozzle heights. These measurements were made at free-stream Mach numbers of 0.00, 0.60, and 1.20 with the nozzle operating at a ratio of nozzle total pressure to free-stream static pressure of 4.0. The jet exhaust was simulated with high-pressure air that had an exit total temperature essentially equal to the free-stream total temperature.

  19. Nozzle seal

    International Nuclear Information System (INIS)

    Herman, R.F.

    1977-01-01

    In an illustrative embodiment of the invention, a nuclear reactor pressure vessel, having an internal hoop from which the heated coolant emerges from the reactor core and passes through to the reactor outlet nozzles, is provided with sealing members operatively disposed between the outlet nozzle and the hoop. The sealing members are biased against the pressure vessel and the hoop and are connected by a leak restraining member establishing a leak-proof condition between the inlet and outlet coolants in the region about the outlet nozzle. Furthermore, the flexible responsiveness of the seal assures that the seal will not structurally couple the hoop to the pressure vessel

  20. Nozzle seal

    International Nuclear Information System (INIS)

    Walling, G.A.

    1977-01-01

    In an illustrative embodiment of the invention, a nuclear reactor pressure vessel, having an internal hoop from which the heated coolant emerges from the reactor core and passes through to the reactor outlet nozzles, is provided with sealing rings operatively disposed between the outlet nozzles and the hoop. The sealing rings connected by flexible members are biased against the pressure vessel and the hoop, establishing a leak-proof condition between the inlet and outlet coolants in the region about the outlet nozzle. Furthermore, the flexible responsiveness of the seal assures that the seal will not structurally couple the hoop to the pressure vessel. 4 claims, 2 figures

  1. 3D nozzle flow simulations including state-to-state kinetics calculation

    Science.gov (United States)

    Cutrone, L.; Tuttafesta, M.; Capitelli, M.; Schettino, A.; Pascazio, G.; Colonna, G.

    2014-12-01

    In supersonic and hypersonic flows, thermal and chemical non-equilibrium is one of the fundamental aspects that must be taken into account for the accurate characterization of the plasma. In this paper, we present an optimized methodology to approach plasma numerical simulation by state-to-state kinetics calculations in a fully 3D Navier-Stokes CFD solver. Numerical simulations of an expanding flow are presented aimed at comparing the behavior of state-to-state chemical kinetics models with respect to the macroscopic thermochemical non-equilibrium models that are usually used in the numerical computation of high temperature hypersonic flows. The comparison is focused both on the differences in the numerical results and on the computational effort associated with each approach.

  2. Jet flow issuing from an axisymmetric pipe-cavity-orifice nozzle

    Directory of Open Access Journals (Sweden)

    Broučková Zuzana

    2016-01-01

    Full Text Available An axisymmetric air jet flow is experimentally investigated under passive flow control. The jet issues from a pipe of the inner diameter and length of 10 mm and 150 mm which is equipped with an axisymmetric cavity at the pipe end. The cavity operates as a resonator creating self-sustained acoustic excitations of the jet flow. A mechanism of excitations is rather complex – in comparison with a common Helmholtz resonator. The experiments were performed using flow visualization, microphone measurements and time-mean velocity measurements by the Pitot probe. The power spectral density (PSD and the sound pressure level (SPL were evaluated from microphone measurements. The jet Reynolds number ranged Re = 1600–18 000. Distinguishable peaks in PSD indicated a function of the resonator. Because the most effective acoustic response was found at higher Re, a majority of experiments focused on higher Re regime. The results demonstrate effects of the passive control on the jet behavior. Fluid mixing and velocity decay along the axis is intensified. It causes shortening of the jet transition region. On the other hand, an inverse proportionality of the velocity decay (u ~ 1/x in the fully developed region is not changed. The momentum and kinetic energy fluxes decrease more intensively in the controlled jets in comparison with common jets.

  3. Vorticity and circulation aspects of twin jets in cross-flow for an oblique nozzle arrangement

    Czech Academy of Sciences Publication Activity Database

    Kolář, Václav; Savory, E.; Takao, H.; Todoroki, T.; Okamoto, S.; Toy, N.

    2006-01-01

    Roč. 220, č. 4 (2006), s. 247-252 ISSN 0954-4100 R&D Projects: GA AV ČR IAA2060302 Institutional research plan: CEZ:AV0Z20600510 Keywords : twin jets in cross-flow * vorticity * circulation Subject RIV: BK - Fluid Dynamics Impact factor: 0.143, year: 2006

  4. A Novel Hybrid Approach for Numerical Modeling of the Nucleating Flow in Laval Nozzle and Transonic Steam Turbine Blades

    Directory of Open Access Journals (Sweden)

    Edris Yousefi Rad

    2017-08-01

    Full Text Available In the present research, considering the importance of desirable steam turbine design, improvement of numerical modeling of steam two-phase flows in convergent and divergent channels and the blades of transonic steam turbines has been targeted. The first novelty of this research is the innovative use of combined Convective Upstream Pressure Splitting (CUSP and scalar methods to update the flow properties at each calculation point. In other words, each property (density, temperature, pressure and velocity at each calculation point can be computed from either the CUSP or scalar method, depending on the least deviation criterion. For this reason this innovative method is named “hybrid method”. The next novelty of this research is the use of an inverse method alongside the proposed hybrid method to find the amount of the important parameter z in the CUSP method, which is herein referred to as “CUSP’s convergence parameter”. Using a relatively simple computational grid, firstly, five cases with similar conditions to those of the main cases under study in this research with available experimental data were used to obtain the value of z by the Levenberg-Marquardt inverse method. With this innovation, first, an optimum value of z = 2.667 was obtained using the inverse method and then directly used for the main cases considered in the research. Given that the aim is to investigate the two-dimensional, steady state, inviscid and adiabatic modeling of steam nucleating flows in three different nozzle and turbine blade geometries, flow simulation was performed using a relatively simple mesh and the innovative proposed hybrid method (scalar + CUSP, with the desired value of z = 2.667 . A comparison between the results of the hybrid modeling of the three main cases with experimental data showed a very good agreement, even within shock zones, including the condensation shock region, revealing the efficiency of this numerical modeling method innovation

  5. Simulation of a Downsized FDM Nozzle

    DEFF Research Database (Denmark)

    Hofstätter, Thomas; Pimentel, Rodrigo; Pedersen, David B.

    2015-01-01

    This document discusses the simulat-ion of a downsized nozzle for fused deposition modelling (FDM), namely the E3D HotEnd Extruder with manufactured diameters of 200-400 μm in the nozzle tip. The nozzle has been simulated in terms of heat transfer and fluid flow giving an insight into the physical...

  6. An experimental study on the effects of swirling oxidizer flow and diameter of fuel nozzle on behaviour and light emittance of propane-oxygen non-premixed flame

    Directory of Open Access Journals (Sweden)

    Javareshkian Alireza

    2017-01-01

    Full Text Available In this study, the stability and the light emittance of non-premixed propane-oxygen flames have been experimentally evaluated with respect to swirling oxidizer flow and variations in fuel nozzle diameter. Hence, three types of the vanes with the swirl angles of 30°, 45°, and 60° have been chosen for producing the desired swirling flows. The main aims of this study are to determine the flame behaviour, light emittance, and also considering the effect of variation in fuel nozzle diameter on combustion phenomena such as flame length, flame shape, and soot free length parameter. The investigation into the flame phenomenology was comprised of variations of the oxidizer and fuel flow velocities (respective Reynolds numbers and the fuel nozzle diameter. The results showed that the swirl effect could change the flame luminosity and this way could reduce or increase the maximum value of the flame light emittance in the combustion zone. Therefore, investigation into the flame light emittance can give a good clue for studying the mixing quality of reactants, the flame phenomenology (blue flame or sooty flame, localized extinction, and the combustion intensity in non-premixed flames.

  7. Numerical investigation on effects of nozzle’s geometric parameters on the flow and the cavitation characteristics within injector’s nozzle for a high-pressure common-rail DI diesel engine

    International Nuclear Information System (INIS)

    Sun, Zuo-Yu; Li, Guo-Xiu; Chen, Chuan; Yu, Yu-Song; Gao, Guo-Xi

    2015-01-01

    Highlights: • The cavitation characteristics within nozzle were numerical studied. • The studied nozzle is from high pressure common-rail injection system. • The effects of nozzle’s geometrical parameters were considered. - Abstract: In the present paper, the influences of nozzle’s geometric parameters on the flow and the cavitation characteristics within injector’s nozzle have been numerically investigated on basis of a high-pressure common-rail DI diesel engine. For obtaining more beneficial information, five essential parameters (the pressure difference on the nozzle, circular bead of nozzle’s inlet, orifice coefficient, the ratio of nozzle’s length to orifice’s diameter, and the roughness of orifice’s inner wall) have been investigated. The variation regulations of the flow and the cavitation characteristics induced by the mentioned parameters have been observed and analysed in terms of the distributions of essential physical fields (including statistic pressure field, velocity magnitude field, turbulent kinetic energy field, mass transfer coefficient field, and vapour’s volume fraction field) and the variation regulations of crucial physical parameters (including mass flow rate, flow coefficient, average vapour’s volume fraction, average flow velocity at orifice’s outlet, and average turbulent kinetic energy at orifice’s outlet). The main results obtained in the present investigation have illustrated how the cavitation occurs, develops and extinguishes within nozzle; meanwhile, how each geometric parameter affects the flow and the cavitation characteristics within nozzle have been explored

  8. Multielement suppressor nozzles for thrust augmentation systems.

    Science.gov (United States)

    Lawrence, R. L.; O'Keefe, J. V.; Tate, R. B.

    1972-01-01

    The noise reduction and nozzle performance characteristics of large-scale, high-aspect-ratio multielement nozzle arrays operated at low velocities were determined by test. The nozzles are selected for application to high-aspect-ratio augmentor suppressors to be used for augmentor wing airplanes. Significant improvements in noise characteristics for multielement nozzles over those of round or high-aspect-ratio slot nozzles are obtained. Elliptical noise patterns typical of slot nozzles are presented for high-aspect-ratio multielement nozzle arrays. Additional advantages are available in OASPL noise reduction from the element size and spacing. Augmentor-suppressor systems can be designed for maximum beam pattern directivity and frequency spectrum shaping advantages. Measurements of the nozzle wakes show a correlation with noise level data and frequency spectrum peaks. The noise and jet wake results are compared with existing prediction procedures based on empirical jet flow equations, Lighthill relationships, Strouhal number, and empirical shock-induced screech noise effects.

  9. Numerical investigation on transient flow and cavitation characteristic within nozzle during the oil drainage process for a high-pressure common-rail DI diesel engine

    International Nuclear Information System (INIS)

    Sun, Zuo-Yu; Li, Guo-Xiu; Yu, Yu-Song; Gao, Si-Chao; Gao, Guo-Xi

    2015-01-01

    Highlights: • The flow process within nozzle during oil drainage process were studied. • The effects of needle movement on flow characteristics were studied. • The cavitation characteristics in a transient flow were numerical studied. - Abstract: In the present investigation, the transient developments of flow and cavitation within an injector’s nozzle during the oil drainage process have been studied by numerical method for a high-pressure common-rail DI diesel engine, both the variation regulations of macro parameters (indicating flow characteristics and cavitation characteristics) and the distribution manners of important physical fields (indicating the cavitation evolution in the micro) have been obtained and analyzed. The obtained numerical results indicate that, during the oil drainage process, both mass flow rate and flow coefficient monotonously increase with declining variation rates, both averaged flow velocity and averaged turbulent kinetic energy also monotonously increase; however, to the curve of TKE-needle lift, there exist certain points give abrupt increase. The difference in TKE curve compared to averaged flow velocity is mainly attributed to the sudden variation of cavitation. Based upon the numerical results, the cavitation bubble will not be formed until the needle lift has been raised to a certain position due to the lower flow velocity and the lack of low (even negative) pressure zones. As needle rises, the primary bubbles are formed near the lower corner after nozzle’s entrance; but as needle further rises, the positions at where bubbles are formed have been transferred to the upper corner and then being blow downwards orifice as the increase of flow velocity

  10. Cross-talk effect in electrostatic based capillary array nozzles

    International Nuclear Information System (INIS)

    Choi, Kyung Hyun; Rahman, Khalid; Khan, Arshad; Kim, Dong Soo

    2011-01-01

    Electrohydrodynamic printing is a promising technique for printed electronics application. Most researchers working in this field are using a single nozzle configuration. However, for large area printing a multi-nozzle setup will be required for time and cost effective process. In this paper the influence of electric field and flow-rate on jetting angle on multi-nozzle array has been investigated experimentally. A three nozzle setup has been used in a linear array by using glass capillary as a nozzle with independent voltage applied on each nozzle and independent ink supply. The experiments are performed by changing the nozzle to nozzle gap and the effect on the jetting angle has been investigated. It has been observed that by increasing the applied voltage the jetting angle also increases at fixed flow-rate. In case of increasing the flow-rate, the jetting angle first increases with increase in flow-rate, but as the flow-rate increases at certain level the jetting angle decreases; moreover, at a high flow-rate the cone-jet length starts increasing. Numerical simulation has been performed to have a better understanding of the electric-field with respect to jetting angles. The influence of one nozzle on another nozzle is also investigated by operating the nozzle independently by using different operating cases. The cross-talk effect is also minimized by reducing the nozzle diameter. At 250 μm nozzle diameter the cross-talk effect was negligible for 5 mm nozzle-to-nozzle gap. This study will help in better understanding of the interaction between different nozzles in multi-nozzle cases and better design of the multi-nozzle system by minimizing the effects of adjacent nozzles for multi-nozzle electrohydrodynamic printing system

  11. Nozzle geometry variations on the discharge coefficient

    Directory of Open Access Journals (Sweden)

    M.M.A. Alam

    2016-03-01

    Full Text Available Numerical works have been conducted to investigate the effect of nozzle geometries on the discharge coefficient. Several contoured converging nozzles with finite radius of curvatures, conically converging nozzles and conical divergent orifices have been employed in this investigation. Each nozzle and orifice has a nominal exit diameter of 12.7×10−3 m. A 3rd order MUSCL finite volume method of ANSYS Fluent 13.0 was used to solve the Reynolds-averaged Navier–Stokes equations in simulating turbulent flows through various nozzle inlet geometries. The numerical model was validated through comparison between the numerical results and experimental data. The results obtained show that the nozzle geometry has pronounced effect on the sonic lines and discharge coefficients. The coefficient of discharge was found differ from unity due to the non-uniformity of flow parameters at the nozzle exit and the presence of boundary layer as well.

  12. An analysis of the shielding gas flow from a coaxial conical nozzle during high power CO{sub 2} laser welding

    Energy Technology Data Exchange (ETDEWEB)

    Ancona, Antonio [CNR-INFM Regional Laboratory LIT3, via Orabona 4, 70126 Bari (Italy); Sibillano, Teresa [CNR-INFM Regional Laboratory LIT3, via Orabona 4, 70126 Bari (Italy); Dipartimento Interateneo di Fisica, Universita Degli Studi di Bari, via Orabona 4, 70126 Bari (Italy); Lugara, Pietro Mario [CNR-INFM Regional Laboratory LIT3, via Orabona 4, 70126 Bari (Italy); Dipartimento Interateneo di Fisica, Universita Degli Studi di Bari, via Orabona 4, 70126 Bari (Italy); Gonnella, Giuseppe [Dipartimento Interateneo di Fisica, Universita Degli Studi di Bari, via Orabona 4, 70126 Bari (Italy); Pascazio, Giuseppe [Dipartimento di Ingegneria Meccanica e Gestionale, Politecnico di Bari, via Re David 200, 70125 Bari (Italy); Centro di Eccellenza in Meccanica Computazionale, Politecnico di Bari, via Re David 200, 70125 Bari (Italy); Maffione, Donato [Dipartimento di Ingegneria Meccanica e Gestionale, Politecnico di Bari, via Re David 200, 70125 Bari (Italy); Centro di Eccellenza in Meccanica Computazionale, Politecnico di Bari, via Re David 200, 70125 Bari (Italy)

    2006-02-07

    An experimental and theoretical study on the role of the nitrogen gas stream, exiting from a conventional conical nozzle tip during a laser welding process, has been carried out. A mathematical model has been used, based on the Navier-Stokes equations which express fundamental conservation laws of mass, momentum and energy for a compressible fluid. Numerical simulations of the gas stream colliding onto a plane surface have been performed showing the effects of variations of inlet gas pressure, nozzle exit diameter and standoff distance on the density and Mach number contours, axis pressure of the gas jet and plate pressure produced on the workpiece surface. Laser welding experiments have been performed on carbon and stainless steel specimens, by varying the process parameters in the same range as in the simulations and keeping constant the incident power and the travel speed. Two different gas stream regimes were found, namely sonic and subsonic, which were experimentally verified to produce cutting and welding conditions, respectively. Weld performances have been evaluated in terms of bead width, penetration depth and melted area. Nozzle standoff distance was found to have a negligible influence, while the exit diameter and the flow rate significantly affect the weld results. The numerical predictions allowed an explanation of the experimental results yielding useful suggestions for enhancing the weld quality, acting simply on the shielding gas parameters.

  13. Chevron's Panna Maria mill process description

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Key features of Chevron's Uranium Mill located near Panna Maria, Texas, are described. The mill is designed to process a nominal 2500 dry tons/day of uranium bearing ore containing 15% uncombined moisture. The following operations at the mill are highlighted: ore receiving, grinding, leaching, countercurrent decantation and tailings disposal, filtering, solvent extraction, solvent stripping, precipitation, drying, and packaging

  14. Arcjet nozzle area ratio effects

    Science.gov (United States)

    Curran, Francis M.; Sarmiento, Charles J.; Birkner, Bjorn W.; Kwasny, James

    1990-01-01

    An experimental investigation was conducted to determine the effect of nozzle area ratio on the operating characteristics and performance of a low power dc arcjet thruster. Conical thoriated tungsten nozzle inserts were tested in a modular laboratory arcjet thruster run on hydrogen/nitrogen mixtures simulating the decomposition products of hydrazine. The converging and diverging sides of the inserts had half angles of 30 and 20 degrees, respectively, similar to a flight type unit currently under development. The length of the diverging side was varied to change the area ratio. The nozzle inserts were run over a wide range of specific power. Current, voltage, mass flow rate, and thrust were monitored to provide accurate comparisons between tests. While small differences in performance were observed between the two nozzle inserts, it was determined that for each nozzle insert, arcjet performance improved with increasing nozzle area ratio to the highest area ratio tested and that the losses become very pronounced for area ratios below 50. These trends are somewhat different than those obtained in previous experimental and analytical studies of low Re number nozzles. It appears that arcjet performance can be enhanced via area ratio optimization.

  15. Arcjet Nozzle Area Ratio Effects

    Science.gov (United States)

    Curran, Francis M.; Sarmiento, Charles J.; Birkner, Bjorn W.; Kwasny, James

    1990-01-01

    An experimental investigation was conducted to determine the effect of nozzle area ratio on the operating characteristics and performance of a low power dc arcjet thruster. Conical thoriated tungsten nozzle inserts were tested in a modular laboratory arcjet thruster run on hydrogen/nitrogen mixtures simulating the decomposition products of hydrazine. The converging and diverging sides of the inserts had half angles of 30 and 20 degrees, respectively, similar to a flight type unit currently under development. The length of the diverging side was varied to change the area ratio. The nozzle inserts were run over a wide range of specific power. Current, voltage, mass flow rate, and thrust were monitored to provide accurate comparisons between tests. While small differences in performance were observed between the two nozzle inserts, it was determined that for each nozzle insert, arcjet performance improved with increasing nozzle area ratio to the highest area ratio tested and that the losses become very pronounced for area ratios below 50. These trends are somewhat different than those obtained in previous experimental and analytical studies of low Re number nozzles. It appears that arcjet performance can be enhanced via area ratio optimization.

  16. Assessment of chevron dikes for the enhancement of physical-aquatic habitat within the Middle Mississippi River, USA

    Science.gov (United States)

    Remo, Jonathan W. F.; Khanal, Anish; Pinter, Nicholas

    2013-09-01

    Blunt-nosed chevron dikes, a new invention now being widely constructed on the Middle Mississippi River (MMR), have been justified as a tool for enhancing physical-aquatic habitat. Chevron dikes were initially designed to concentrate flow, induce channel scour, and thus facilitate river navigation. More recently, these structures have been justified, in part, for promoting habitat heterogeneity. The ability of chevrons to create and diversify physical-aquatic habitat, however, has not been empirically evaluated. To assess the ability of chevrons to create and diversify physical-aquatic habitat, we compiled hydrologic and geospatial data for three channel reference conditions along a 2.0 km (∼140 ha) reach of the MMR where three chevrons were constructed in late 2007. We used the hydrologic and hydraulic data to construct detailed 2-D hydrodynamic models for three reference condition: historic (circa 1890), pre-chevron, and post-chevron channel conditions. These models documented changes in depths and flow dynamics for a wide range of in-channel discharges. Depth-velocity habitat classes were used to assess change in physical-aquatic habitat patches and spatial statistical tools in order to evaluate the reach-scale habitat patch diversity. Comparisons of pre- and post-chevron conditions revealed increases in deep to very deep (>3.0 m) areas of slow moving (3.0 m], low velocity [<0.6 m/s]). Chevron construction also created some (0.8-3.8 ha) shallow-water habitat (0-1.5 m depth with a 0-0.6 m/s velocity) for flows ⩽2.0 × MAF and contributed to an 8-35% increase in physical-aquatic-habitat diversity compared to pre-chevron channel conditions. However, modeling of the historic reference condition (less engineered channel, circa 1890) revealed that the historical physical-aquatic-habitat mosaic consisted of a wider and shallower channel with: 45-390% more shallow-water habitat (2.4-11.0 ha) and 22-83% more physical-aquatic-habitat diversity, but little over

  17. Efficiency of using direct-flow burners and nozzles in implementation of dry-bottom ash removal at the TPP-210A boiler furnace

    Science.gov (United States)

    Arkhipov, A. M.; Kanunnikov, A. A.; Kirichkov, V. S.; Prokhorov, V. B.; Fomenko, M. V.; Chernov, S. L.

    2017-02-01

    In reconstruction of operating pulverized coal-fired boilers, one of the main factors is the choice of a method for slag removal: dry bottom ash removal (DBAR) or slag-tap removal (STR). In this case, ecological and economic aspects should be taken into account, and also the early ignition of pulverized coal fuel, the reliability of operation of the furnace walls in the mode without slagging, and the stability of slag removal should be provided. In this work, issues of changeover of the pulverized coal-fired boilers of the TPP-210A type from the STR mode to the DBAR mode are considered. As of today, the main problems during the operation of these boilers are the high emissions of nitrogen oxides together with flue gases into the atmosphere and the appropriated payoffs, a small range of loads available, the necessity of stabilization of the pulverizedcoal flame sustainability by using the highly reactive fuel, large mechanical fuel underburning, etc. Results of studying aerodynamics of a furnace with DBAR obtained in the process of physical simulation are given; technical solutions and preliminary design (configuration of burners and nozzles in the boiler furnace, conceptual design of the pulverized coal burner, configuration of TPP-210A boiler with the low heat liberation of furnace cross-section and volumetric heat release) are set forth, which are associated with the optimization of aerodynamics of furnace volume, when the direct-flow burners and nozzles are used, and with organization of the efficient staged combustion of solid fuel. Two versions of possible modernization of a boiler unit are considered. Under conditions of the planned increase in the steam production capacity, the most promising measures are as follows: the DBAR implementation with reducing heat releases of the cross-section and volume of the furnace approximately by half, the installation of the direct-flow burners and nozzles with injection of recirculation gases into the active combustion

  18. Effect of Shrouding Gas Temperature on Characteristics of a Supersonic Jet Flow Field with a Shrouding Laval Nozzle Structure

    Science.gov (United States)

    Liu, Fuhai; Sun, Dongbai; Zhu, Rong; Li, Yilin

    2018-05-01

    Coherent jet technology was been widely used in the electric arc furnace steelmaking process to protect the kinetic energy of supersonic oxygen jets and achieve a better mixing effect. For this technology, the total temperature distribution of the shrouding jet has a great impact on the velocity of the main oxygen jet. In this article, a supersonic shrouding nozzle using a preheating shrouding jet is proposed to increase the shrouding jet velocity. Both numerical simulation and experimental studies were carried out to analyze its effect on the axial velocity, total temperature and turbulence kinetic energy profiles of the main oxygen jet. Based on these results, it was found that a significant amount of kinetic energy was removed from the main oxygen jet when it passed though the shock wave using a high-temperature shrouding jet, which made the average axial velocity of the coherent jet lower than for a conventional jet in the potential core region. However, the supersonic shrouding nozzle and preheating technology employed for this nozzle design significantly improved the shrouding gas velocity, forming a low-density gas zone at the exit of the main oxygen jet and prolonging the velocity potential core length.

  19. Parametric Study of Sealant Nozzle

    Science.gov (United States)

    Yamamoto, Yoshimi

    It has become apparent in recent years the advancement of manufacturing processes in the aerospace industry. Sealant nozzles are a critical device in the use of fuel tank applications for optimal bonds and for ground service support and repair. Sealants has always been a challenging area for optimizing and understanding the flow patterns. A parametric study was conducted to better understand geometric effects of sealant flow and to determine whether the sealant rheology can be numerically modeled. The Star-CCM+ software was used to successfully develop the parametric model, material model, physics continua, and simulate the fluid flow for the sealant nozzle. The simulation results of Semco sealant nozzles showed the geometric effects of fluid flow patterns and the influences from conical area reduction, tip length, inlet diameter, and tip angle parameters. A smaller outlet diameter induced maximum outlet velocity at the exit, and contributed to a high pressure drop. The conical area reduction, tip angle and inlet diameter contributed most to viscosity variation phenomenon. Developing and simulating 2 different flow models (Segregated Flow and Viscous Flow) proved that both can be used to obtain comparable velocity and pressure drop results, however; differences are seen visually in the non-uniformity of the velocity and viscosity fields for the Viscous Flow Model (VFM). A comprehensive simulation setup for sealant nozzles was developed so other analysts can utilize the data.

  20. Premixed direct injection nozzle

    Science.gov (United States)

    Zuo, Baifang [Simpsonville, SC; Johnson, Thomas Edward [Greer, SC; Lacy, Benjamin Paul [Greer, SC; Ziminsky, Willy Steve [Simpsonville, SC

    2011-02-15

    An injection nozzle having a main body portion with an outer peripheral wall is disclosed. The nozzle includes a plurality of fuel/air mixing tubes disposed within the main body portion and a fuel flow passage fluidly connected to the plurality of fuel/air mixing tubes. Fuel and air are partially premixed inside the plurality of the tubes. A second body portion, having an outer peripheral wall extending between a first end and an opposite second end, is connected to the main body portion. The partially premixed fuel and air mixture from the first body portion gets further mixed inside the second body portion. The second body portion converges from the first end toward said second end. The second body portion also includes cooling passages that extend along all the walls around the second body to provide thermal damage resistance for occasional flame flash back into the second body.

  1. Focusing liquid microjets with nozzles

    International Nuclear Information System (INIS)

    Acero, A J; Ferrera, C; Montanero, J M; Gañán-Calvo, A M

    2012-01-01

    The stability of flow focusing taking place in a converging–diverging nozzle, as well as the size of the resulting microjets, is examined experimentally in this paper. The results obtained in most aspects of the problem are similar to those of the classical plate-orifice configuration. There is, however, a notable difference between flow focusing in nozzles and in the plate-orifice configuration. In the former case, the liquid meniscus oscillates laterally (global whipping) for a significant area of the control parameter plane, a phenomenon never observed when focusing with the plate-orifice configuration. Global whipping may constitute an important drawback of flow focusing with nozzles because it reduces the robustness of the technique. (paper)

  2. Computational study of performance characteristics for truncated conical aerospike nozzles

    Science.gov (United States)

    Nair, Prasanth P.; Suryan, Abhilash; Kim, Heuy Dong

    2017-12-01

    Aerospike nozzles are advanced rocket nozzles that can maintain its aerodynamic efficiency over a wide range of altitudes. It belongs to class of altitude compensating nozzles. A vehicle with an aerospike nozzle uses less fuel at low altitudes due to its altitude adaptability, where most missions have the greatest need for thrust. Aerospike nozzles are better suited to Single Stage to Orbit (SSTO) missions compared to conventional nozzles. In the current study, the flow through 20% and 40% aerospike nozzle is analyzed in detail using computational fluid dynamics technique. Steady state analysis with implicit formulation is carried out. Reynolds averaged Navier-Stokes equations are solved with the Spalart-Allmaras turbulence model. The results are compared with experimental results from previous work. The transition from open wake to closed wake happens in lower Nozzle Pressure Ratio for 20% as compared to 40% aerospike nozzle.

  3. Design and Analyses of High Aspect Ratio Nozzles for Distributed Propulsion Acoustic Measurements

    Science.gov (United States)

    Dippold, Vance F., III

    2016-01-01

    A series of three convergent round-to-rectangular high-aspect ratio nozzles were designed for acoustics measurements. The nozzles have exit area aspect ratios of 8:1, 12:1, and 16:1. With septa inserts, these nozzles will mimic an array of distributed propulsion system nozzles, as found on hybrid wing-body aircraft concepts. Analyses were performed for the three nozzle designs and showed that the flow through the nozzles was free of separated flow and shocks. The exit flow was mostly uniform with the exception of a pair of vortices at each span-wise end of the nozzle.

  4. Investigation of turbines for driving supersonic compressors II : performance of first configuration with 2.2 percent reduction in nozzle flow area / Warner L. Stewart, Harold J. Schum, Robert Y. Wong

    Science.gov (United States)

    Stewart, Warner L; Schum, Harold J; Wong, Robert Y

    1952-01-01

    The experimental performance of a modified turbine for driving a supersonic compressor is presented and compared with the performance of the original configuration to illustrate the effect of small changes in the ratio of nozzle-throat area to rotor-throat area. Performance is based on the performance of turbines designed to operate with both blade rows close to choking. On the basis of the results of this investigation, the ratio of areas is concluded to become especially critical in the design of turbines such as those designed to drive high-speed, high-specific weight-flow compressors where the turbine nozzles and rotor are both very close to choking.

  5. Nozzle airfoil having movable nozzle ribs

    Science.gov (United States)

    Yu, Yufeng Phillip; Itzel, Gary Michael

    2002-01-01

    A nozzle vane or airfoil structure is provided in which the nozzle ribs are connected to the side walls of the vane or airfoil in such a way that the ribs provide the requisite mechanical support between the concave side and convex side of the airfoil but are not locked in the radial direction of the assembly, longitudinally of the airfoil. The ribs may be bi-cast onto a preformed airfoil side wall structure or fastened to the airfoil by an interlocking slide connection and/or welding. By attaching the nozzle ribs to the nozzle airfoil metal in such a way that allows play longitudinally of the airfoil, the temperature difference induced radial thermal stresses at the nozzle airfoil/rib joint area are reduced while maintaining proper mechanical support of the nozzle side walls.

  6. External Cylindrical Nozzle with Controlled Vacuum

    Directory of Open Access Journals (Sweden)

    V. N. Pil'gunov

    2015-01-01

    Full Text Available There is a developed design of the external cylindrical nozzle with a vacuum camera. The paper studies the nozzle controllability of flow rate via regulated connection of the evacuated chamber to the atmosphere through an air throttle. Working capacity of the nozzle with inlet round or triangular orifice are researched. The gap is provided in the nozzle design between the external wall of the inlet orifice and the end face of the straight case in the nozzle case. The presented mathematical model of the nozzle with the evacuated chamber allows us to estimate the expected vacuum amount in the compressed section of a stream and maximum permissible absolute pressure at the inlet orifice. The paper gives experimental characteristics of the fluid flow process through the nozzle for different values of internal diameter of a straight case and an extent of its end face remoteness from an external wall of the inlet orifice. It estimates how geometry of nozzle constructive elements influences on the volume flow rate. It is established that the nozzle capacity significantly depends on the shape of inlet orifice. Triangular orifice nozzles steadily work in the mode of completely filled flow area of the straight case at much more amounts of the limit pressure of the flow. Vacuum depth in the evacuated chamber also depends on the shape of inlet orifice: the greatest vacuum is reached in a nozzle with the triangular orifice which 1.5 times exceeds the greatest vacuum with the round orifice. Possibility to control nozzle capacity through the regulated connection of the evacuated chamber to the atmosphere was experimentally estimated, thus depth of flow rate regulation of the nozzle with a triangular orifice was 45% in comparison with 10% regulation depth of the nozzle with a round orifice. Depth of regulation calculated by a mathematical model appeared to be much more. The paper presents experimental dependences of the flow coefficients of nozzle input orifice

  7. Laval nozzles for cluster-jet targets

    Energy Technology Data Exchange (ETDEWEB)

    Grieser, Silke; Bonaventura, Daniel; Hergemoeller, Ann-Katrin; Hetz, Benjamin; Koehler, Esperanza; Lessmann, Lukas; Khoukaz, Alfons [Institut fuer Kernphysik, Westfaelische Wilhelms-Universitaet Muenster, 48149 Muenster (Germany)

    2016-07-01

    Cluster-jet targets are highly suited for storage ring experiments due to the fact that they provide high and constant beam densities. Therefore, a cluster-jet target is planned to be the first internal target for the PANDA experiment at FAIR. A cluster source generates a continuous flow of cryogenic solid clusters by the expansion of pre-cooled gases within fine Laval nozzles. For the production of clusters the geometry of the nozzle is crucial. The production of such nozzles with their complex inner geometry represents a major technical challenge. The possibility to produce new fine Laval nozzles ensures the operation of cluster-jet targets, e.g. for the PANDA experiment, and opens the way for future investigations on the cluster production process to match the required targets performance. Optimizations on the recently developed production process and the fabrication of new glass nozzles were done. Initial measurements of these nozzles at the PANDA cluster-jet target prototype and the investigation of the cluster beam origin within the nozzle will be presented and discussed. For the future more Laval nozzles with different geometries will be produced and additional measurements with these new nozzles at the PANDA cluster-jet target prototype towards higher performance will be realized.

  8. Effect of Channel Geometry and Properties of a Vapor-Gas Mixture on Volume Condensation in a Flow through a Nozzle

    Science.gov (United States)

    Sidorov, A. A.; Yastrebov, A. K.

    2018-01-01

    A method of direct numerical solution of the kinetic equation for the droplet size distribution function was used for the numerical investigation of volume condensation in a supersonic vapor-gas flow. Distributions of temperature for the gas phase and droplets, degree of supersaturation, pressure, fraction of droplets by weight, the number of droplets per unit mass, and of the nucleation rate along the channel were determined. The influence of nozzle geometry, mixture composition, and temperature dependence of the mixture properties on the investigated process was evaluated. It has been found that the nozzle divergence angle determines the vapor-gas mixture expansion rate: an increase in the divergence angle enhances the temperature decrease rate and the supersaturation degree raise rate. With an increase or decrease in the partial pressure of incondensable gas, the droplet temperature approaches the gas phase temperature or the saturation temperature at the partial gas pressure, respectively. A considerable effect of the temperature dependence of the liquid surface tension and properties on gas phase parameters and the integral characteristics of condensation aerosol was revealed. However, the difference in results obtained with or without considering the temperature dependence of evaporation heat is negligible. The predictions are compared with experimental data of other investigations for two mixtures: a mixture of heavy water vapor with nitrogen (incondensable gas) or n-nonane vapor with nitrogen. The predictions agree quite well qualitatively and quantitatively with the experiment. The comparison of the predictions with numerical results from other publications obtained using the method of moments demonstrates the usefulness of the direct numerical solution method and the method of moments in a wide range of input data.

  9. Design and analysis approach for linear aerospike nozzle

    International Nuclear Information System (INIS)

    Khan, S.U.; Khan, A.A.; Munir, A.

    2014-01-01

    The paper presents an aerodynamic design of a simplified linear aerospike nozzle and its detailed exhaust flow analysis with no spike truncation. Analytical method with isentropic planar flow was used to generate the nozzle contour through MATLAB . The developed code produces a number of outputs comprising nozzle wall profile, flow properties along the nozzle wall, thrust coefficient, thrust, as well as amount of nozzle truncation. Results acquired from design code and numerical analyses are compared for observing differences. The numerical analysis adopted an inviscid model carried out through commercially available and reliable computational fluid dynamics (CFD) software. Use of the developed code would assist the readers to perform quick analysis of different aerodynamic design parameters for the aerospike nozzle that has tremendous scope of application in future launch vehicles. Keyword: Rocket propulsion, Aerospike Nozzle, Control Design, Computational Fluid Dynamics. (author)

  10. Turbocharger with variable nozzle having vane sealing surfaces

    Science.gov (United States)

    Arnold, Philippe [Hennecourt, FR; Petitjean, Dominique [Julienrupt, FR; Ruquart, Anthony [Thaon les Vosges, FR; Dupont, Guillaume [Thaon les Vosges, FR; Jeckel, Denis [Thaon les Vosges, FR

    2011-11-15

    A variable nozzle for a turbocharger includes a plurality of vanes rotatably mounted on a nozzle ring and disposed in a nozzle flow path defined between the nozzle ring and an opposite nozzle wall. Either or both of the faces of the nozzle ring and nozzle wall include(s) at least one step that defines sealing surfaces positioned to be substantially abutted by airfoil surfaces of the vanes in the closed position of the vanes and to be spaced from the airfoil surfaces in positions other than the closed position. This substantial abutment between the airfoil surfaces and the sealing surfaces serves to substantially prevent exhaust gas from leaking past the ends of the airfoil portions. At the same time, clearances between the nozzle ring face and the end faces of the airfoil portions can be sufficiently large to prevent binding of the vanes under all operating conditions.

  11. Pitot survey of exhaust flow field of a 2-D scramjet nozzle at Mach 6 with air or freon and argon used for exhaust simulation

    Science.gov (United States)

    Monta, William J.

    1992-01-01

    A pitot-rake survey of the simulated exhaust of a half-span scramjet nozzle model was conducted in the Langley 20-Inch Mach 6 Tunnel to provide an additional data set for computational fluid dynamics (CFD) code comparisons. A wind-tunnel model was tested with a 26-tube pitot rake that could be manually positioned along the mid-semispan plane of the model. The model configuration had an external expansion surface of 20 degrees and an internal cowl expansion of 12 degrees; tests were also performed with a flow fence. Tests were conducted at a free-stream Reynolds number of approximately 6.5 x 10(exp 6) per foot and a model angle of attack of -0.75 degrees. The two exhaust gas mediums that were tested were air and a Freon 12-argon mixture. Each medium was tested at two jet total pressures at approximately 28 and 14 psia. This document presents the flow-field survey results in graphical as well as tabular form, and several observations concerning the results are discussed. The surveys reveal the major expected flow-field characteristics for each test configuration. For a 50-percent freon 12 and 50-percent argon mixture by volume (Fr-Ar), the exhaust jet pressures were slightly higher than those for air. The addition of a flow fence slightly raised the pitot pressure for the Fr-Ar mixture, but it produced little change for air. For the Fr-Ar exhaust, the plume was larger and the region between the shock wave and plume was smaller.

  12. Cold spray nozzle design

    Science.gov (United States)

    Haynes, Jeffrey D [Stuart, FL; Sanders, Stuart A [Palm Beach Gardens, FL

    2009-06-09

    A nozzle for use in a cold spray technique is described. The nozzle has a passageway for spraying a powder material, the passageway having a converging section and a diverging section, and at least the diverging section being formed from polybenzimidazole. In one embodiment of the nozzle, the converging section is also formed from polybenzimidazole.

  13. Prototype Morphing Fan Nozzle Demonstrated

    Science.gov (United States)

    Lee, Ho-Jun; Song, Gang-Bing

    2004-01-01

    Ongoing research in NASA Glenn Research Center's Structural Mechanics and Dynamics Branch to develop smart materials technologies for aeropropulsion structural components has resulted in the design of the prototype morphing fan nozzle shown in the photograph. This prototype exploits the potential of smart materials to significantly improve the performance of existing aircraft engines by introducing new inherent capabilities for shape control, vibration damping, noise reduction, health monitoring, and flow manipulation. The novel design employs two different smart materials, a shape-memory alloy and magnetorheological fluids, to reduce the nozzle area by up to 30 percent. The prototype of the variable-area fan nozzle implements an overlapping spring leaf assembly to simplify the initial design and to provide ease of structural control. A single bundle of shape memory alloy wire actuators is used to reduce the nozzle geometry. The nozzle is subsequently held in the reduced-area configuration by using magnetorheological fluid brakes. This prototype uses the inherent advantages of shape memory alloys in providing large induced strains and of magnetorheological fluids in generating large resistive forces. In addition, the spring leaf design also functions as a return spring, once the magnetorheological fluid brakes are released, to help force the shape memory alloy wires to return to their original position. A computerized real-time control system uses the derivative-gain and proportional-gain algorithms to operate the system. This design represents a novel approach to the active control of high-bypass-ratio turbofan engines. Researchers have estimated that such engines will reduce thrust specific fuel consumption by 9 percent over that of fixed-geometry fan nozzles. This research was conducted under a cooperative agreement (NCC3-839) at the University of Akron.

  14. Effect of the mixing fields on the stability and structure of turbulent partially premixed flames in a concentric flow conical nozzle burner

    KAUST Repository

    Mansour, Mohy S.

    2016-10-22

    The mixing field is known to be one of the key parameters that affect the stability and structure of partially premixed flames. Data in these flames are now available covering the effects of turbulence, combustion system geometry, level of partially premixing and fuel type. However, quantitative analyses of the flame structure based on the mixing field are not yet available. The aim of this work is to present a comprehensive study of the effects of the mixing fields on the structure and stability of partially premixed methane flames. The mixing field in a concentric flow conical nozzle (CFCN) burner with well-controlled mechanism of the mixing is investigated using Rayleigh scattering technique. The flame stability, structure and flow field of some selected cases are presented using LIF of OH and PIV. The experimental data of the mixing field cover wide ranges of Reynolds number, equivalence ratio and mixing length. The data show that the mixing field is significantly affected by the mixing length and the ratio of the air-to-fuel velocities. The Reynolds number has a minimum effect on the mixing field in high turbulent flow regime and the stability is significantly affected by the turbulence level. The temporal fluctuations of the range of mixture fraction within the mixing field correlate with the flame stability. The highest point of stability occurs at recess distances where fluid mixtures near the jet exit plane are mostly within the flammability limits. This paper provides some correlations between the stability range in mixture fraction space and the turbulence level for different equivalence ratios.

  15. Safety performance evaluation of converging chevron pavement markings : final report.

    Science.gov (United States)

    2014-12-01

    The objectives of this study were (1) to perform a detailed safety analysis of converging chevron : pavement markings, quantifying the potential safety benefits and developing an understanding of the : incident types addressed by the treatment, and (...

  16. CFD Analysis On The Performance Of Wind Turbine With Nozzles

    Directory of Open Access Journals (Sweden)

    Chunkyraj Kh

    2015-08-01

    Full Text Available In this paper an effort has been made in dealing with fluid characteristic that enters a converging nozzle and analysis of the nozzle is carried out using Computational Fluid Dynamics package ANSYS WORKBENCH 14.5. The paper is the continuation of earlier work Analytical and Experimental performance evaluation of Wind turbine with Nozzles. First the CFD analysis will be carried out on nozzle in-front of wind turbine where streamline velocity at the exit volume flow rate in the nozzle and pressure distribution across the nozzle will be studied. Experiments were conducted on the Wind turbine with nozzles and the corresponding power output at different air speed and different size of nozzles were calculated. Different shapes and dimensions with special contours and profiles of nozzles were studied. It was observed that the special contour nozzles have superior outlet velocity and low pressure at nozzle exit the design has maximum Kinetic energy. These indicators conclude that the contraction designed with the new profile is a good enhancing of the nozzle performance.

  17. Through an Annular Turbine Nozzle

    Directory of Open Access Journals (Sweden)

    Rainer Kurz

    1995-01-01

    is located in the gas turbine. The experiments were performed using total pressure probes and wall static pressure taps. The pitch variation modifies the flow field both upstream and downstream of the nozzle, although the experiments show that the effect is localized to the immediate neighborhood of the involved blades. The effects on the wakes and on the inviscid flow are discussed separately. The mean velocities show a strong sensitivity to the changes of the pitch, which is due to a potential flow effect rather than a viscous effect.

  18. Variable volume combustor with aerodynamic fuel flanges for nozzle mounting

    Science.gov (United States)

    McConnaughhay, Johnie Franklin; Keener, Christopher Paul; Johnson, Thomas Edward; Ostebee, Heath Michael

    2016-09-20

    The present application provides a combustor for use with a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles and a fuel injection system for providing a flow of fuel to the micro-mixer fuel nozzles. The fuel injection system may include a number of support struts supporting the fuel nozzles and for providing the flow of fuel therethrough. The fuel injection system also may include a number of aerodynamic fuel flanges connecting the micro-mixer fuel nozzles and the support struts.

  19. Analysis of Nozzle Jet Plume Effects on Sonic Boom Signature

    Science.gov (United States)

    Bui, Trong

    2010-01-01

    An axisymmetric full Navier-Stokes computational fluid dynamics (CFD) study was conducted to examine nozzle exhaust jet plume effects on the sonic boom signature of a supersonic aircraft. A simplified axisymmetric nozzle geometry, representative of the nozzle on the NASA Dryden NF-15B Lift and Nozzle Change Effects on Tail Shock (LaNCETS) research airplane, was considered. The highly underexpanded nozzle flow is found to provide significantly more reduction in the tail shock strength in the sonic boom N-wave pressure signature than perfectly expanded and overexpanded nozzle flows. A tail shock train in the sonic boom signature, similar to what was observed in the LaNCETS flight data, is observed for the highly underexpanded nozzle flow. The CFD results provide a detailed description of the nozzle flow physics involved in the LaNCETS nozzle at different nozzle expansion conditions and help in interpreting LaNCETS flight data as well as in the eventual CFD analysis of a full LaNCETS aircraft. The current study also provided important information on proper modeling of the LaNCETS aircraft nozzle. The primary objective of the current CFD research effort was to support the LaNCETS flight research data analysis effort by studying the detailed nozzle exhaust jet plume s imperfect expansion effects on the sonic boom signature of a supersonic aircraft. Figure 1 illustrates the primary flow physics present in the interaction between the exhaust jet plume shock and the sonic boom coming off of an axisymmetric body in supersonic flight. The steeper tail shock from highly expanded jet plume reduces the dip of the sonic boom N-wave signature. A structured finite-volume compressible full Navier-Stokes CFD code was used in the current study. This approach is not limited by the simplifying assumptions inherent in previous sonic boom analysis efforts. Also, this study was the first known jet plume sonic boom CFD study in which the full viscous nozzle flow field was modeled, without

  20. Advanced exhaust nozzle technology

    Energy Technology Data Exchange (ETDEWEB)

    Glidewell, R J; Warburton, R E

    1981-01-01

    Recent developments in turbine engine exhaust nozzle technology include nonaxisymmetric nozzles, thrust reversing, and thrust vectoring. Trade studies have been performed to determine the impact of these developments on the thrust-to-weight ratio and specific fuel consumption of an advanced high performance, augmented turbofan engine. Results are presented in a manner which provides an understanding of the sources and magnitudes of differences in the basic elements of nozzle internal performance and weight as they relate to conventional, axisymmetric nozzle technology. Conclusions are presented and recommendations are made with regard to future directions of advanced development and demonstration. 5 refs.

  1. Lower nozzle of PWR fuel assembly

    International Nuclear Information System (INIS)

    Furutani, Nobuo.

    1994-01-01

    A lower nozzle comprises a regular square plate and legs. The plate has a plurality of holes for securing thimble tubes and a great number of water flowing ports. Ridges each having a lower end surface inclined toward inner side of the plate are disposed at the outer circumference of the plate. The legs suspend downwardly from the corners of the plate and support the plate at a predetermined gap between a lower reactor core plate and the plate. The inclined surfaces of the ridges disposed at the outer circumference of the plate retain coolants, that were caused to flow to the outside passing between the legs of the nozzle, while dividing them to the inside of the nozzle and circulate the coolants upwardly passing through the water flowing ports of the plate. Further, since obstacles abut against the inclined surfaces of the ridges and flow to the inner side of the lower nozzle, obstacles in the coolants can be captured substantially entirely by the lower nozzle. (I.N.)

  2. Proposed Chevron Tengiz venture stalls amid Soviet political squabble

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    This paper reports on the status of foreign investment in Soviet oil and gas joint ventures which has reached a critical juncture. Just as the U.S. is considering granting most favored nation trade status to the U.S.S.R., the joint venture petroleum deal seen as the litmus test for such deals-Chevron Corp.'s proposed addition of supergiant Tengiz oil field to its Caspian Sea joint venture-has stalled amid controversy. Unconfirmed reports from Soviet officials and other foreign joint venture participants in the U.S.S.R. have Chevron pulling out of the long negotiated, multibillion dollar project after the Soviets rejected the company's terms. Chevron, however, insists the project is still alive

  3. Experimental study of subsonic microjet escaping from a rectangular nozzle

    Science.gov (United States)

    Aniskin, V. M.; Maslov, A. A.; Mukhin, K. A.

    2016-10-01

    The first experiments on the subsonic laminar microjets escaping from the nozzles of rectangular shape are carried out. The nozzle size is 83.3x3823 microns. Reynolds number calculated by the nozzle height and the average flow velocity at the nozzle exit ranged from 58 to 154. The working gas was air at room temperature. The velocity decay and velocity fluctuations along the center line of the jet are determined. The fundamental difference between the laminar microjets characteristics and subsonic turbulent jets of macro size is shown. Based on measurements of velocity fluctuations it is shown the presence of laminar-turbulent transition in microjets and its location is determined.

  4. Novel design for transparent high-pressure fuel injector nozzles

    Science.gov (United States)

    Falgout, Z.; Linne, M.

    2016-08-01

    The efficiency and emissions of internal combustion (IC) engines are closely tied to the formation of the combustible air-fuel mixture. Direct-injection engines have become more common due to their increased practical flexibility and efficiency, and sprays dominate mixture formation in these engines. Spray formation, or rather the transition from a cylindrical liquid jet to a field of isolated droplets, is not completely understood. However, it is known that nozzle orifice flow and cavitation have an important effect on the formation of fuel injector sprays, even if the exact details of this effect remain unknown. A number of studies in recent years have used injectors with optically transparent nozzles (OTN) to allow observation of the nozzle orifice flow. Our goal in this work is to design various OTN concepts that mimic the flow inside commercial injector nozzles, at realistic fuel pressures, and yet still allow access to the very near nozzle region of the spray so that interior flow structure can be correlated with primary breakup dynamics. This goal has not been achieved until now because interior structures can be very complex, and the most appropriate optical materials are brittle and easily fractured by realistic fuel pressures. An OTN design that achieves realistic injection pressures and grants visual access to the interior flow and spray formation will be explained in detail. The design uses an acrylic nozzle, which is ideal for imaging the interior flow. This nozzle is supported from the outside with sapphire clamps, which reduces tensile stresses in the nozzle and increases the nozzle's injection pressure capacity. An ensemble of nozzles were mechanically tested to prove this design concept.

  5. Study of nozzle deposit formation mechanism for direct injection gasoline engines; Chokufun gasoline engine yo nozzle no deposit seisei kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, M; Saito, A [Toyota Central Research and Development Labs., Inc., Aichi (Japan); Matsushita, S [Toyota Motor Corp., Aichi (Japan); Shibata, H [Nippon Soken, Inc., Tokyo (Japan); Niwa, Y [Denso Corp., Aichi (Japan)

    1997-10-01

    Nozzles in fuel injectors for direct injection gasoline engines are exposed to high temperature combustion gases and soot. In such a rigorous environment, it is a fear that fuel flow rate changes in injectors by deposit formation on nozzles. Fundamental factors of nozzle deposit formation were investigated through injector bench tests and engine dynamometer tests. Deposit formation processes were observed by SEM through engine dynamometer tests. The investigation results reveal nozzle deposit formation mechanism and how to suppress the deposit. 4 refs., 8 figs., 3 tabs.

  6. Jet-Surface Interaction: High Aspect Ratio Nozzle Test, Nozzle Design and Preliminary Data

    Science.gov (United States)

    Brown, Clifford; Dippold, Vance

    2015-01-01

    The Jet-Surface Interaction High Aspect Ratio (JSI-HAR) nozzle test is part of an ongoing effort to measure and predict the noise created when an aircraft engine exhausts close to an airframe surface. The JSI-HAR test is focused on parameters derived from the Turbo-electric Distributed Propulsion (TeDP) concept aircraft which include a high-aspect ratio mailslot exhaust nozzle, internal septa, and an aft deck. The size and mass flow rate limits of the test rig also limited the test nozzle to a 16:1 aspect ratio, half the approximately 32:1 on the TeDP concept. Also, unlike the aircraft, the test nozzle must transition from a single round duct on the High Flow Jet Exit Rig, located in the AeroAcoustic Propulsion Laboratory at the NASA Glenn Research Center, to the rectangular shape at the nozzle exit. A parametric nozzle design method was developed to design three low noise round-to-rectangular transitions, with 8:1, 12:1, and 16: aspect ratios, that minimizes flow separations and shocks while providing a flat flow profile at the nozzle exit. These designs validated using the WIND-US CFD code. A preliminary analysis of the test data shows that the actual flow profile is close to that predicted and that the noise results appear consistent with data from previous, smaller scale, tests. The JSI-HAR test is ongoing through October 2015. The results shown in the presentation are intended to provide an overview of the test and a first look at the preliminary results.

  7. On periodically excited turbulent mixing layer created downstream of a plane Chevron partition

    International Nuclear Information System (INIS)

    Kit, E; Wygnanski, I

    2008-01-01

    The flow in a turbulent mixing layer resulting from the merger of two parallel, different velocity streams, created downstream of a 'Chevron'-shaped jagged partition was simulated numerically on the basis of experiments published in 2007. A small flap that was hinged at the trailing edge of the partition could oscillate at a prescribed frequency, and induce regular oscillations in the flow. The latter regulated the large eddy structure that was amenable to phase-locked data acquisition revealing the large spanwise vortices that were generated by Kelvin-Helmholtz instability and streamwise vortices that were triggered by the chevron and were enhanced by a secondary instability in the flow. These, being locked in phase, were mapped by using particle image velocimetry. Numerical simulation of the equations of motion was then carried out in order to reveal the most unstable mechanisms leading to the generation of the streamwise vortical structure. The simulation started by assuming the flow to be two-dimensional (2D) and allowing the large spanwise eddies to develop temporally. At a prescribed time (or the state of development of the large spanwise rolls) the 2D computation was frozen and 3D simulation initiated. The latter exhibited typical evolution of translative instability, which bent the large spanwise structures and stretched some of them to create streamwise vorticity. Bulging of the spanwise eddies was also observed, but the bulging instability is a slower process than the bending one. The results of the simulations compare well to experiments and provide some understanding of this complex interaction.

  8. Computational Simulation on a Coaxial Substream Powder Feeding Laval Nozzle of Cold Spraying

    Directory of Open Access Journals (Sweden)

    Guosheng HUANG

    2014-09-01

    Full Text Available In this paper, a substream coaxial powder feeding nozzle was investigated for use in cold spraying. The relationship between nozzle structure and gas flow, the acceleration behavior of copper particles were examined by computational simulation method. Also, one of the nozzle was used to spray copper coating on steel substrate. The simulation results indicate that: the velocity of gas at the center of the nozzle is lower than that of the conventional nozzle. Powders are well restrained near the central line of the nozzle, no collision occurred between the nozzle wall and the powders. This type of nozzle with expansion 3.25 can successfully deposit copper coating on steel substrate, the copper coating has low porosity about 3.1 % – 3.8 % and high bonding strength about 23.5 MPa – 26.8 MPa. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4244

  9. Study on steam pressure characteristics in various types of nozzles

    Science.gov (United States)

    Firman; Anshar, Muhammad

    2018-03-01

    Steam Jet Refrigeration (SJR) is one of the most widely applied technologies in the industry. The SJR system was utilizes residual steam from the steam generator and then flowed through the nozzle to a tank that was containing liquid. The nozzle converts the pressure energy into kinetic energy. Thus, it can evaporate the liquid briefly and release it to the condenser. The chilled water, was produced from the condenser, can be used to cool the product through a heat transfer process. This research aims to study the characteristics of vapor pressure in different types of nozzles using a simulation. The Simulation was performed using ANSYS FLUENT software for nozzle types such as convergent, convrgent-parallel, and convergent-divergent. The results of this study was presented the visualization of pressure in nozzles and was been validated with experiment data.

  10. Characterisation of subsonic axisymmetric nozzles

    Czech Academy of Sciences Publication Activity Database

    Tesař, Václav

    2008-01-01

    Roč. 86, č. 11 (2008), s. 1253-1262 ISSN 0263-8762 R&D Projects: GA AV ČR IAA200760705 Institutional research plan: CEZ:AV0Z20760514 Keywords : nozzle * characterisation * nozzle properties * nozzle invariants Subject RIV: BK - Fluid Dynamics Impact factor: 0.989, year: 2008

  11. Flame Interactions and Thermoacoustics in Multiple-Nozzle Combustors

    Science.gov (United States)

    Dolan, Brian

    between the two nozzles. A decrease in inter-nozzle spacing resulted in a penalty to the lean blowout point and NO X emissions. Particle image velocimetry shows that the nozzle spacing also has an important effect on the flowfield of the nozzles including the shape of the recirculation region and the quantitative flow velocities. In particular, interaction in the tangential velocity between the two nozzles has large effects on the swirl number and the recirculation zone. Numerical simulations of the isothermal airflows of two pilot nozzles are validated using experimental measurements and used to provide flowfield information outside of the measurement domain. At wider inter-nozzle spacings under certain reacting conditions, an alternating flow pattern develops in the combustion chamber. The shear layers of one nozzle extent into the combustion chamber whereas the inlet reactants from the other nozzle attach near the dome wall to create a very wide recirculation region. Combustion properties, including the fuel type, are shown experimentally to affect whether or not a system will develop an alternating pattern. Simplified computational models of two interacting swirling flows are used to parametrically study the effects of nozzle exit geometry and swirl number on an alternating pattern. Both parameters are shown to be potential drivers of an alternating pattern under some conditions. A hypothesis that proposes a physical mechanism explaining the alternating flow pattern, consistent with the work in this proposal and the research of other groups, is presented. When the nozzle design, flow, or combustion characteristics cause the shear layers of the adjacent nozzles to become sufficiently opposite in direction, the two flows can no longer mix. Instead, one shear layer goes underneath the other which results in the differing flow features of the adjacent nozzles.

  12. Fabrication of Microglass Nozzle for Microdroplet Jetting

    Directory of Open Access Journals (Sweden)

    Dan Xie

    2015-02-01

    Full Text Available An ejection aperture nozzle is the essential part for all microdrop generation techniques. The diameter size, the flow channel geometry, and fluid impedance are the key factors affecting the ejection capacity. A novel low-cost fabrication method of microglass nozzle involving four steps is developed in this work. In the first heating step, the glass pipette is melted and pulled. Then, the second heating step is to determine the tip cone angle and modify the flow channel geometry. The desired included angle is usually of 30~45 degrees. Fine grind can determine the exact diameter of the hole. Postheating step is the final process and it can reduce the sharpness of the edges of the hole. Micronozzles with hole diameters varying from 30 to 100 µm are fabricated by the homemade inexpensive and easy-to-operate setup. Hydrophobic treating method of microglass nozzle to ensure stable and accurate injection is also introduced in this work. According to the jetting results of aqueous solution, UV curing adhesive, and solder, the fabricated microglass nozzle can satisfy the need of microdroplet jetting of multimaterials.

  13. Articles which include chevron film cooling holes, and related processes

    Science.gov (United States)

    Bunker, Ronald Scott; Lacy, Benjamin Paul

    2014-12-09

    An article is described, including an inner surface which can be exposed to a first fluid; an inlet; and an outer surface spaced from the inner surface, which can be exposed to a hotter second fluid. The article further includes at least one row or other pattern of passage holes. Each passage hole includes an inlet bore extending through the substrate from the inlet at the inner surface to a passage hole-exit proximate to the outer surface, with the inlet bore terminating in a chevron outlet adjacent the hole-exit. The chevron outlet includes a pair of wing troughs having a common surface region between them. The common surface region includes a valley which is adjacent the hole-exit; and a plateau adjacent the valley. The article can be an airfoil. Related methods for preparing the passage holes are also described.

  14. Single absorbable polydioxanone pin fixation for distal chevron bunion osteotomies.

    Science.gov (United States)

    Deorio, J K; Ware, A W

    2001-10-01

    The distal chevron osteotomy is a well-established technique for correction of symptomatic mild to moderate metatarsus primus varus with hallux valgus deformity. Fixation of the osteotomy ranges from none to bone pegs, Kirschner wires, screws, or absorbable pins. We evaluated one surgeon's (J.K.D.) results of distal chevron osteotomy fixation with a single, nonpredrilled, 1.3-mm poly-p-dioxanone pin and analyzed any differences in patients with unilateral or bilateral symptomatic metatarsus primus varus with hallux valgus deformities. All osteotomies healed without evidence of infection, osteolysis, nonunion, or necrosis. Equal correction was achieved in unilateral and bilateral procedures. The technique is quick and easy, and adequate fixation is achieved.

  15. Duplex tab exhaust nozzle

    Science.gov (United States)

    Gutmark, Ephraim Jeff (Inventor); Martens, Steven (nmn) (Inventor)

    2012-01-01

    An exhaust nozzle includes a conical duct terminating in an annular outlet. A row of vortex generating duplex tabs are mounted in the outlet. The tabs have compound radial and circumferential aft inclination inside the outlet for generating streamwise vortices for attenuating exhaust noise while reducing performance loss.

  16. Coherent structures in a supersonic complex nozzle

    Science.gov (United States)

    Magstadt, Andrew; Berry, Matthew; Glauser, Mark

    2016-11-01

    The jet flow from a complex supersonic nozzle is studied through experimental measurements. The nozzle's geometry is motivated by future engine designs for high-performance civilian and military aircraft. This rectangular jet has a single plane of symmetry, an additional shear layer (referred to as a wall jet), and an aft deck representative of airframe integration. The core flow operates at a Mach number of Mj , c = 1 . 6 , and the wall jet is choked (Mj , w = 1 . 0). This high Reynolds number jet flow is comprised of intense turbulence levels, an intricate shock structure, shear and boundary layers, and powerful corner vortices. In the present study, stereo PIV measurements are simultaneously sampled with high-speed pressure measurements, which are embedded in the aft deck, and far-field acoustics in the anechoic chamber at Syracuse University. Time-resolved schlieren measurements have indicated the existence of strong flow events at high frequencies, at a Strouhal number of St = 3 . 4 . These appear to result from von Kàrmàn vortex shedding within the nozzle and pervade the entire flow and acoustic domain. Proper orthogonal decomposition is applied on the current data to identify coherent structures in the jet and study the influence of this vortex street. AFOSR Turbulence and Transition Program (Grant No. FA9550-15-1-0435) with program managers Dr. I. Leyva and Dr. R. Ponnappan.

  17. Distal Metatarsal Osteotomy in Hallux Valgus Surgery: Chevron Osteotomy

    Directory of Open Access Journals (Sweden)

    Fatih Dogar

    2016-04-01

    Full Text Available Aim: Hallux valgus is a complex foot deformity resulting from medial deviation of first metatarsal and lateral deviation of toe. Radiographic and functional outcomes of chevron type distal metatarsal osteotomy applied to symptomatic hallux valgus patients with moderate deformity were assessed in the present study. Chevron osteotomy was applied to 27 feet (13 left, 14 right of 22 patients (12 women and 10 men; mean age: 45±16.7 years. Mean follow-up was 15.4± 4.71 months (range, 10%u201324. Material and Method: The average preoperative AOFAS score of 39.1 ± 8.55 (range, 32%u201357 improved (p < 0.0001 to 87.8 ± 4.7 (range, 82%u201397. The average preoperative hallux valgus angle (HVA of 37.4 ± 5.8 (range, 29%u201350 improved (p < 0.0001 to 14.8 ± 3.1 (range, 10%u201320 , and the average preoperative intermetatarsal 1-2 angle (IMA of 13.1 ± 1.5 (range, 11%u201317 improved (p < 0.0001 to 7.1 ± 1.4 (range, 5%u20139 . The average sesamoid position improved from 2.9 ± 0.2 (range, 2-3 preoperatively to 1.2 ± 0.4 (range, 1-2 (p < 0.0001. Toe hypoesthesia was developed in one patient as a complication. At the end of follow-up, patient satisfaction was found to be excellent in 16 feet (59.2% and good in 11 feet (40.8%. Results: The results of the study that chevron osteotomy yields good radiological result, high degree of postoperative patient satisfaction with minimal complications. Chevron ostoetomy is most effective method in the treatment of moderate hallux valgus.

  18. A static investigation of yaw vectoring concepts on two-dimensional convergent-divergent nozzles

    Science.gov (United States)

    Berrier, B. L.; Mason, M. L.

    1983-01-01

    The flow-turning capability and nozzle internal performance of yaw-vectoring nozzle geometries were tested in the NASA Langley 16-ft Transonic wind tunnel. The concept was investigated as a means of enhancing fighter jet performance. Five two-dimensional convergent-divergent nozzles were equipped for yaw-vectoring and examined. The configurations included a translating left sidewall, left and right sidewall flaps downstream of the nozzle throat, left sidewall flaps or port located upstream of the nozzle throat, and a powered rudder. Trials were also run with 20 deg of pitch thrust vectoring added. The feasibility of providing yaw-thrust vectoring was demonstrated, with the largest yaw vector angles being obtained with sidewall flaps downstream of the nozzle primary throat. It was concluded that yaw vector designs that scoop or capture internal nozzle flow provide the largest yaw-vector capability, but decrease the thrust the most.

  19. CFD SIMULATION OF THE HEAT TRANSFER PROCESS IN A CHEVRON PLATE HEAT EXCHANGER USING THE SST TURBULENCE MODEL

    Directory of Open Access Journals (Sweden)

    Jan Skočilas

    2015-08-01

    Full Text Available This paper deals with a computational fluid dynamics (CFD simulation of the heat transfer process during turbulent hot water flow between two chevron plates in a plate heat exchanger. A three-dimensional model with the simplified geometry of two cross-corrugated channels provided by chevron plates, taking into account the inlet and outlet ports, has been designed for the numerical study. The numerical model was based on the shear-stress transport (SST k-! model. The basic characteristics of the heat exchanger, as values of heat transfer coefficient and pressure drop, have been investigated. A comparative analysis of analytical calculation results, based on experimental data obtained from literature, and of the results obtained by numerical simulation, has been carried out. The coefficients and the exponents in the design equations for the considered plates have been arranged by using simulation results. The influence on the main flow parameters of the corrugation inclination angle relative to the flow direction has been taken into account. An analysis of the temperature distribution across the plates has been carried out, and it has shown the presence of zones with higher heat losses and low fluid flow intensity.

  20. An Interactive Method of Characteristics Java Applet to Design and Analyze Supersonic Aircraft Nozzles

    Science.gov (United States)

    Benson, Thomas J.

    2014-01-01

    The Method of Characteristics (MOC) is a classic technique for designing supersonic nozzles. An interactive computer program using MOC has been developed to allow engineers to design and analyze supersonic nozzle flow fields. The program calculates the internal flow for many classic designs, such as a supersonic wind tunnel nozzle, an ideal 2D or axisymmetric nozzle, or a variety of plug nozzles. The program also calculates the plume flow produced by the nozzle and the external flow leading to the nozzle exit. The program can be used to assess the interactions between the internal, external and plume flows. By proper design and operation of the nozzle, it may be possible to lessen the strength of the sonic boom produced at the rear of supersonic aircraft. The program can also calculate non-ideal nozzles, such as simple cone flows, to determine flow divergence and nonuniformities at the exit, and its effect on the plume shape. The computer program is written in Java and is provided as free-ware from the NASA Glenn central software server.

  1. Turbine combustor with fuel nozzles having inner and outer fuel circuits

    Science.gov (United States)

    Uhm, Jong Ho; Johnson, Thomas Edward; Kim, Kwanwoo

    2013-12-24

    A combustor cap assembly for a turbine engine includes a combustor cap and a plurality of fuel nozzles mounted on the combustor cap. One or more of the fuel nozzles would include two separate fuel circuits which are individually controllable. The combustor cap assembly would be controlled so that individual fuel circuits of the fuel nozzles are operated or deliberately shut off to provide for physical separation between the flow of fuel delivered by adjacent fuel nozzles and/or so that adjacent fuel nozzles operate at different pressure differentials. Operating a combustor cap assembly in this fashion helps to reduce or eliminate the generation of undesirable and potentially harmful noise.

  2. Design and Checkout of a High Speed Research Nozzle Evaluation Rig

    Science.gov (United States)

    Castner, Raymond S.; Wolter, John D.

    1997-01-01

    The High Flow Jet Exit Rig (HFJER) was designed to provide simulated mixed flow turbojet engine exhaust for one- seventh scale models of advanced High Speed Research test nozzles. The new rig was designed to be used at NASA Lewis Research Center in the Nozzle Acoustic Test Rig and the 8x6 Supersonic Wind Tunnel. Capabilities were also designed to collect nozzle thrust measurement, aerodynamic measurements, and acoustic measurements when installed at the Nozzle Acoustic Test Rig. Simulated engine exhaust can be supplied from a high pressure air source at 33 pounds of air per second at 530 degrees Rankine and nozzle pressure ratios of 4.0. In addition, a combustion unit was designed from a J-58 aircraft engine burner to provide 20 pounds of air per second at 2000 degrees Rankine, also at nozzle pressure ratios of 4.0. These airflow capacities were designed to test High Speed Research nozzles with exhaust areas from eighteen square inches to twenty-two square inches. Nozzle inlet flow measurement is available through pressure and temperature sensors installed in the rig. Research instrumentation on High Speed Research nozzles is available with a maximum of 200 individual pressure and 100 individual temperature measurements. Checkout testing was performed in May 1997 with a 22 square inch ASME long radius flow nozzle. Checkout test results will be summarized and compared to the stated design goals.

  3. Effects of dimensional size and surface roughness on service performance for a micro Laval nozzle

    International Nuclear Information System (INIS)

    Cai, Yukui; Liu, Zhanqiang; Shi, Zhenyu

    2017-01-01

    Nozzles with large and small dimensions are widely used in various industries. The main objective of this research is to investigate the effects of dimensional size and surface roughness on the service performance of a micro Laval nozzle. The variation of nozzle service performance from the conventional macro to micro scale is presented in this paper. This shows that the dimensional nozzle size has a serious effect on the nozzle gas flow friction. With the decrease of nozzle size, the velocity performance and thrust performance deteriorate. The micro nozzle performance has less sensitivity to the variation of surface roughness than the large scale nozzle does. Surface quality improvement and burr prevention technologies are proposed to reduce the friction effect on the micro nozzle performance. A novel process is then developed to control and depress the burr generation during micro nozzle machining. The polymethyl-methacrylate as a coating material is coated on the rough machined surface before finish machining. Finally, the micro nozzle with a throat diameter of 1 mm is machined successfully. Thrust test results show that the implement and application of this machining process benefit the service performance improvement of the micro nozzle. (paper)

  4. Limit loads in nozzles

    International Nuclear Information System (INIS)

    Zouain, N.

    1983-01-01

    The static method for the evaluation of the limit loads of a perfectly elasto-plastic structure is presented. Using the static theorem of Limit Analysis and the Finite Element Method, a lower bound for the colapso load can be obtained through a linear programming problem. This formulation if then applied to symmetrically loaded shells of revolution and some numerical results of limit loads in nozzles are also presented. (Author) [pt

  5. Design and performance of atomizing nozzles for spray calcination of high-level wastes

    International Nuclear Information System (INIS)

    Miller, F.A.; Stout, L.A.

    1981-05-01

    A key aspect of high-level liquid-waste spray calcination is waste-feed atomization by using air atomizing nozzles. Atomization substantially increases the heat transfer area of the waste solution, which enhances rapid drying. Experience from the spray-calciner operations has demonstrated that nozzle flow conditions that produce 70-μ median-volume-diameter or smaller spray droplets are required for small-scale spray calciners (drying capacity less than 80 L/h). For large-scale calciners (drying capacity greater than 300 L/h), nozzle flow conditions that produce 100-μ median-volume-diameter or smaller spray droplets are required. Mass flow ratios of 0.2 to 0.4, depending on nozzle size, are required for proper operation of internal-mix atomizing nozzles. Both internal-mix and external-mix nozzles have been tested at PNL. Due to the lower airflow requirements and fewer large droplets produced, the internal-mix nozzle has been chosen for primary development in the spray calciner program at PNL. Several nozzle air-cap materials for internal-mix nozzles have been tested for wear resistance. Results show that nozzle air caps of stainless steel and Cer-vit (a machineable glass ceramic) are suceptible to rapid wear by abrasive slurries, whereas air caps of alumina and reaction-bonded silicon nitride show only slow wear. Longer-term testing is necessary to determine more accurately the actual frequency of nozzle replacement. Atomizing nozzle air caps of alumina are subject to fracture from thermal shock, whereas air caps of silicon nitride and Cer-vit are not. Fractured nozzles are held in place by the air-cap retaining ring and continue to atomize satisfactorily. Therefore, fractures caused by thermal shocking do not necessarily result in nozzle failure

  6. Analysis of film cooling in rocket nozzles

    Science.gov (United States)

    Woodbury, Keith A.

    1992-01-01

    Computational Fluid Dynamics (CFD) programs are customarily used to compute details of a flow field, such as velocity fields or species concentrations. Generally they are not used to determine the resulting conditions at a solid boundary such as wall shear stress or heat flux. However, determination of this information should be within the capability of a CFD code, as the code supposedly contains appropriate models for these wall conditions. Before such predictions from CFD analyses can be accepted, the credibility of the CFD codes upon which they are based must be established. This report details the progress made in constructing a CFD model to predict the heat transfer to the wall in a film cooled rocket nozzle. Specifically, the objective of this work is to use the NASA code FDNS to predict the heat transfer which will occur during the upcoming hot-firing of the Pratt & Whitney 40K subscale nozzle (1Q93). Toward this end, an M = 3 wall jet is considered, and the resulting heat transfer to the wall is computed. The values are compared against experimental data available in Reference 1. Also, FDNS's ability to compute heat flux in a reacting flow will be determined by comparing the code's predictions against calorimeter data from the hot firing of a 40K combustor. The process of modeling the flow of combusting gases through the Pratt & Whitney 40K subscale combustor and nozzle is outlined. What follows in this report is a brief description of the FDNS code, with special emphasis on how it handles solid wall boundary conditions. The test cases and some FDNS solution are presented next, along with comparison to experimental data. The process of modeling the flow through a chamber and a nozzle using the FDNS code will also be outlined.

  7. Head spray nozzle in reactor pressure vessel

    International Nuclear Information System (INIS)

    Hatano, Shun-ichi.

    1990-01-01

    In a reactor pressure vessel of a BWR type reactor, a head spray nozzle is used for cooling the head of the pressure vessel and, in view of the thermal stresses, it is desirable that cooling is applied as uniformly as possible. A conventional head spray is constituted by combining full cone type nozzles. Since the sprayed water is flown down upon water spraying and the sprayed water in the vertical direction is overlapped, the flow rate distribution has a high sharpness to form a shape as having a maximum value near the center and it is difficult to obtain a uniform flow rate distribution in the circumferential direction. Then, in the present invention, flat nozzles each having a spray water cross section of laterally long shape, having less sharpness in the circumferential distribution upon spraying water to the inner wall of the pressure vessel and having a wide angle of water spray are combined, to make the flow rate distribution of spray water uniform in the inner wall of the pressure vessel. Accordingly, the pressure vessel can be cooled uniformly and thermal stresses upon cooling can be decreased. (N.H.)

  8. Experimental investigation and exergy analysis of the performance of a counter flow Ranque-Hilsch vortex tube with regard to nozzle cross-section areas

    Energy Technology Data Exchange (ETDEWEB)

    Dincer, K.; Avci, A.; Berber, A. [Dept. of Mechanical Eng., Fac. of Eng. and Architecture, Selcuk Univ., Selcuklu, Konya (Turkey); Baskaya, S. [Dept. of Mechanical Eng., Fac. of Eng. and Architecture, Gazi Univ., Maltepe, Ankara (Turkey)

    2010-08-15

    Exergy analysis and performance of a Ranque-Hilsch Vortex Tube (RHVT) with various nozzle cross-section areas (NCSA = 3 x 3, 4 x 4, 5 x 5 mm{sup 2}) were determined under inlet pressures (P{sub i}) of 260, 300 kPa (absolute) pressurized air. The maximum difference in the temperatures of hot output and cold output streams was obtained for NCSA = 3 x 3 mm{sup 2}. The total inlet exergy (sum E{sub i}), total outlet exergy (sum E{sub O}), total lost exergy (sum E{sub Lost}) and exergy efficiency ({eta}, %) were calculated. It was determined that the exergy efficiency of the system, varied between 1% and 39%, and the highest exergy efficiency was obtained for NCSA = 3 x 3 mm{sup 2}. The exergy efficiency strongly depends on the level of P{sub i}, {xi} and v{sub cold}. Variation of the exergy efficiency decreased with decreasing P{sub i}, {xi}, v{sub cold} and the highest and lowest exergy efficiencies were found when the values of P{sub i}, {xi}, v{sub cold} reached maximum and minimum levels, respectively. (author)

  9. Development of built-in debris-filter bottom nozzle for PWR fuel assemblies

    International Nuclear Information System (INIS)

    Juntaro Shimizu; Kazuki Monaka; Masaji Mori; Kazuo Ikeda

    2005-01-01

    Mitsubishi Heavy Industries, Ltd. (MHI) has worked to improve the capability of anti debris bottom nozzle for a PWR fuel assembly. The Current debris filter bottom nozzle (DFBN) having 4mm diameter flow holes can capture the larger size of debris than the flow hole inner diameter. MHI has completed the development of the built-in debris filter bottom nozzle, which is the new idea of the debris-filter for high burnup (55GWd/t assembly average burnup). Built-in debris filter bottom nozzle consists of the blades and nozzle body. The blades made from inconel strip are embedded and welded on the grooved top surface of the bottom nozzle adapter plate. A flow hole is divided by the blade and the trap size of the debris is reduced. Because the blades block the coolant flow, it was anticipated to increase the pressure loss of the nozzle, however, adjusting the relation between blade and taper shape of the flow hole, the pressure loss has been successfully maintained the satisfactory level. Grooves are cut on the nozzle plate; nevertheless, the additional skirts on the four sides of the nozzle compensate the structural strength. (authors)

  10. Plasma acceleration by magnetic nozzles and shock waves

    International Nuclear Information System (INIS)

    Hattori, Kunihiko; Murakami, Fumitake; Miyazaki, Hiroyuki; Imasaki, Atsushi; Yoshinuma, Mikirou; Ando, Akira; Inutake, Masaaki

    2001-01-01

    We have measured axial profiles of ion acoustic Mach number, M i , of a plasma flow blowing off from an MPD (magneto-plasma-dynamic) arc-jet in various magnetic configurations. It is found that the Mach number increases in a divergent nozzle up to 3, while it stays at about unity in a uniform magnetic channel. When a magnetic bump is added in the exit of the divergent magnetic nozzle, the Mach number suddenly decreases below unity, due to an occurrence of shock wave. The subsonic flow after the shock wave is re-accelerated to a supersonic flow through a magnetic Laval nozzle. This behavior is explained well by the one-dimensional isotropic flow model. The shock wave is discussed in relation to the Rankine-Hugoniot relation. (author)

  11. Shock unsteadiness in a thrust optimized parabolic nozzle

    Science.gov (United States)

    Verma, S. B.

    2009-07-01

    This paper discusses the nature of shock unsteadiness, in an overexpanded thrust optimized parabolic nozzle, prevalent in various flow separation modes experienced during start up {(δ P0 /δ t > 0)} and shut down {(δ P0/δ t The results are based on simultaneously acquired data from real-time wall pressure measurements using Kulite pressure transducers, high-speed schlieren (2 kHz) of the exhaust flow-field and from strain-gauges installed on the nozzle bending tube. Shock unsteadiness in the separation region is seen to increase significantly just before the onset of each flow transition, even during steady nozzle operation. The intensity of this measure ( rms level) is seen to be strongly influenced by relative locations of normal and overexpansion shock, the decrease in radial size of re-circulation zone in the back-flow region, and finally, the local nozzle wall contour. During restricted shock separation, the pressure fluctuations in separation region exhibit periodic characteristics rather than the usually observed characteristics of intermittent separation. The possible physical mechanisms responsible for the generation of flow unsteadiness in various separation modes are discussed. The results are from an experimental study conducted in P6.2 cold-gas subscale test facility using a thrust optimized parabolic nozzle of area-ratio 30.

  12. Next-generation nozzle check valve significantly reduces operating costs

    Energy Technology Data Exchange (ETDEWEB)

    Roorda, O. [SMX International, Toronto, ON (Canada)

    2009-01-15

    Check valves perform an important function in preventing reverse flow and protecting plant and mechanical equipment. However, the variety of different types of valves and extreme differences in performance even within one type can change maintenance requirements and life cycle costs, amounting to millions of dollars over the typical 15-year design life of piping components. A next-generation non-slam nozzle check valve which prevents return flow has greatly reduced operating costs by protecting the mechanical equipment in a piping system. This article described the check valve varieties such as the swing check valve, a dual-plate check valve, and nozzle check valves. Advancements in optimized design of a non-slam nozzle check valve were also discussed, with particular reference to computer flow modelling such as computational fluid dynamics; computer stress modelling such as finite element analysis; and flow testing (using rapid prototype development and flow loop testing), both to improve dynamic performance and reduce hydraulic losses. The benefits of maximized dynamic performance and minimized pressure loss from the new designed valve were also outlined. It was concluded that this latest non-slam nozzle check valve design has potential applications in natural gas, liquefied natural gas, and oil pipelines, including subsea applications, as well as refineries, and petrochemical plants among others, and is suitable for horizontal and vertical installation. The result of this next-generation nozzle check valve design is not only superior performance, and effective protection of mechanical equipment but also minimized life cycle costs. 1 fig.

  13. Measurement of unsteady airflow velocity at nozzle outlet

    Science.gov (United States)

    Pyszko, René; Machů, Mário

    2017-09-01

    The paper deals with a method of measuring and evaluating the cooling air flow velocity at the outlet of the flat nozzle for cooling a rolled steel product. The selected properties of the Prandtl and Pitot sensing tubes were measured and compared. A Pitot tube was used for operational measurements of unsteady dynamic pressure of the air flowing from nozzles to abtain the flow velocity. The article also discusses the effects of air temperature, pressure and relative air humidity on air density, as well as the influence of dynamic pressure filtering on the error of averaged velocity.

  14. Chevron osteotomy for the treatment of hallux valgus.

    Science.gov (United States)

    Horne, G; Tanzer, T; Ford, M

    1984-03-01

    Seventy-six chevron osteotomies with follow-up periods ranging from six months to eight years were reviewed. The majority of patients had pain over the bunion prior to operation, and 27 also presented with second metatarsalgia. After surgery there was a marked decrease of pain in the first metatarsophalangeal joint, and in 18 feet the second metatarsalgia was either eliminated or markedly decreased. Most patients were pleased with the appearance of the feet after surgery, but almost one-third of the women complained of difficulty in wearing high heels. The surgical technique is straightforward, but careful attention to detail is necessary to obtain a consistent and satisfactory result.

  15. The effects of a spray slurry nozzle on copper CMP for reduction in slurry consumption

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Da Sol; Jeong, Hae Do [Pusan National University, Busan (Korea, Republic of); Lee, Hyun Seop [Tongmyong University, Busan (Korea, Republic of)

    2015-12-15

    The environmental impact of semiconductor manufacturing has been a big social problem, like greenhouse gas emission. Chemical mechanical planarization (CMP), a wet process which consumes chemical slurries, seriously impacts environmental sustain ability and cost-effectiveness. This paper demonstrates the superiority of a full-cone spray slurry nozzle to the conventional tube-type slurry nozzle in Cu CMP. It was observed that the spray nozzle made a weak slurry wave at the retaining ring unlike a conventional nozzle, because the slurry was supplied uniformly in broader areas. Experiments were implemented with different slurry flow rates and spray nozzle heights. Spray nozzle performance is controlled by the spray angle and spray height. The process temperature was obtained with an infrared (IR) sensor and an IR thermal imaging camera to investigate the cooling effect of the spray. The results show that the spray nozzle provides a higher Material removal rate (MRR), lower non-uniformity (NU), and lower temperature than the conventional nozzle. Computational fluid dynamics techniques show that the turbulence kinetic energy and slurry velocity of the spray nozzle are much higher than those of the conventional nozzle. Finally, it can be summarized that the spray nozzle plays a significant role in slurry efficiency by theory of Minimum quantity lubrication (MQL).

  16. The effects of a spray slurry nozzle on copper CMP for reduction in slurry consumption

    International Nuclear Information System (INIS)

    Lee, Da Sol; Jeong, Hae Do; Lee, Hyun Seop

    2015-01-01

    The environmental impact of semiconductor manufacturing has been a big social problem, like greenhouse gas emission. Chemical mechanical planarization (CMP), a wet process which consumes chemical slurries, seriously impacts environmental sustain ability and cost-effectiveness. This paper demonstrates the superiority of a full-cone spray slurry nozzle to the conventional tube-type slurry nozzle in Cu CMP. It was observed that the spray nozzle made a weak slurry wave at the retaining ring unlike a conventional nozzle, because the slurry was supplied uniformly in broader areas. Experiments were implemented with different slurry flow rates and spray nozzle heights. Spray nozzle performance is controlled by the spray angle and spray height. The process temperature was obtained with an infrared (IR) sensor and an IR thermal imaging camera to investigate the cooling effect of the spray. The results show that the spray nozzle provides a higher Material removal rate (MRR), lower non-uniformity (NU), and lower temperature than the conventional nozzle. Computational fluid dynamics techniques show that the turbulence kinetic energy and slurry velocity of the spray nozzle are much higher than those of the conventional nozzle. Finally, it can be summarized that the spray nozzle plays a significant role in slurry efficiency by theory of Minimum quantity lubrication (MQL).

  17. High performance Solid Rocket Motor (SRM) submerged nozzle/combustion cavity flowfield assessment

    Science.gov (United States)

    Freeman, J. A.; Chan, J. S.; Murph, J. E.; Xiques, K. E.

    1987-01-01

    Two and three dimensional internal flowfield solutions for critical points in the Space Shuttle solid rocket booster burn time were developed using the Lockheed Huntsville GIM/PAID Navier-Stokes solvers. These perfect gas, viscous solutions for the high performance motor characterize the flow in the aft segment and nozzle of the booster. Two dimensional axisymmetric solutions were developed at t = 20 and t = 85 sec motor burn times. The t = 85 sec solution indicates that the aft segment forward inhibitor stub produces vortices with are shed and convected downwards. A three dimensional 3.5 deg gimbaled nozzle flowfield solution was developed for the aft segment and nozzle at t = 9 sec motor burn time. This perfect gas, viscous analysis, provided a steady state solution for the core region and the flow through the nozzle, but indicated that unsteady flow exists in the region under the nozzle nose and near the flexible boot and nozzle/case joint. The flow in the nozzle/case joint region is characterized by low magnitude pressure waves which travel in the circumferential direction. From the two and three dimensional flowfield calculations presented it can be concluded that there is no evidence from these results that steady state gas dynamics is the primary mechanism resulting in the nozzle pocketing erosion experienced on SRM nozzles 8A or 17B. The steady state flowfield results indicate pocketing erosion is not directly initiated by a steady state gas dynamics phenomenon.

  18. Effect of nozzle arrangement on Venturi scrubber performance

    Energy Technology Data Exchange (ETDEWEB)

    Ananthanarayanan, N.V.; Viswanathan, S.

    1999-12-01

    The effect of nozzle arrangement on flux distribution is studied in a rectangular, pilot-scale, Pease-Anthony-type Venturi scrubber. The annular, two-phase, heterogeneous, three-dimensional gas-liquid flow inside the scrubber is modeled using a commercial computational fluid dynamic (CFD) package, FLUENT. The comparison of predicted liquid drop concentration shows good agreement with experimental data. The model predicts the fraction of liquid flowing as film on the walls reasonably well. Visualization of flux patterns studied using four typical nozzle configurations indicate that the nonuniformity in flux distribution increases when the nozzle-to-nozzle distance is greater than 10% of the width of the side on which the nozzles are placed. An analysis of the effect of multiple jet penetration lengths on liquid flux distribution yielded a comparable distribution at 10--45% less liquid than uniform penetration for a particular nozzle configuration. This would lead to significant improvements in scrubber performance by achieving comparable collection efficiency at a lower pressure drop.

  19. Chevron beam dump for ITER edge Thomson scattering system

    International Nuclear Information System (INIS)

    Yatsuka, E.; Hatae, T.; Bassan, M.; Itami, K.; Vayakis, G.

    2013-01-01

    This paper contains the design of the beam dump for the ITER edge Thomson scattering system and mainly concerns its lifetime under the harsh thermal and electromagnetic loads as well as tight space allocation. The lifetime was estimated from the multi-pulse laser-induced damage threshold. In order to extend its lifetime, the structure of the beam dump was optimized. A number of bent sheets aligned parallel in the beam dump form a shape called a chevron which enables it to avoid the concentration of the incident laser pulse energy. The chevron beam dump is expected to withstand thermal loads due to nuclear heating, radiation from the plasma, and numerous incident laser pulses throughout the entire ITER project with a reasonable margin for the peak factor of the beam profile. Structural analysis was also carried out in case of electromagnetic loads during a disruption. Moreover, detailed issues for more accurate assessments of the beam dump's lifetime are clarified. Variation of the bi-directional reflection distribution function (BRDF) due to erosion by or contamination of neutral particles derived from the plasma is one of the most critical issues that needs to be resolved. In this paper, the BRDF was assumed, and the total amount of stray light and the absorbed laser energy profile on the beam dump were evaluated

  20. Chevron beam dump for ITER edge Thomson scattering system

    Energy Technology Data Exchange (ETDEWEB)

    Yatsuka, E.; Hatae, T.; Bassan, M.; Itami, K. [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Vayakis, G. [ITER Organization, 13115 St Paul Lez Durance Cedex (France)

    2013-10-15

    This paper contains the design of the beam dump for the ITER edge Thomson scattering system and mainly concerns its lifetime under the harsh thermal and electromagnetic loads as well as tight space allocation. The lifetime was estimated from the multi-pulse laser-induced damage threshold. In order to extend its lifetime, the structure of the beam dump was optimized. A number of bent sheets aligned parallel in the beam dump form a shape called a chevron which enables it to avoid the concentration of the incident laser pulse energy. The chevron beam dump is expected to withstand thermal loads due to nuclear heating, radiation from the plasma, and numerous incident laser pulses throughout the entire ITER project with a reasonable margin for the peak factor of the beam profile. Structural analysis was also carried out in case of electromagnetic loads during a disruption. Moreover, detailed issues for more accurate assessments of the beam dump's lifetime are clarified. Variation of the bi-directional reflection distribution function (BRDF) due to erosion by or contamination of neutral particles derived from the plasma is one of the most critical issues that needs to be resolved. In this paper, the BRDF was assumed, and the total amount of stray light and the absorbed laser energy profile on the beam dump were evaluated.

  1. Chevron beam dump for ITER edge Thomson scattering system.

    Science.gov (United States)

    Yatsuka, E; Hatae, T; Vayakis, G; Bassan, M; Itami, K

    2013-10-01

    This paper contains the design of the beam dump for the ITER edge Thomson scattering system and mainly concerns its lifetime under the harsh thermal and electromagnetic loads as well as tight space allocation. The lifetime was estimated from the multi-pulse laser-induced damage threshold. In order to extend its lifetime, the structure of the beam dump was optimized. A number of bent sheets aligned parallel in the beam dump form a shape called a chevron which enables it to avoid the concentration of the incident laser pulse energy. The chevron beam dump is expected to withstand thermal loads due to nuclear heating, radiation from the plasma, and numerous incident laser pulses throughout the entire ITER project with a reasonable margin for the peak factor of the beam profile. Structural analysis was also carried out in case of electromagnetic loads during a disruption. Moreover, detailed issues for more accurate assessments of the beam dump's lifetime are clarified. Variation of the bi-directional reflection distribution function (BRDF) due to erosion by or contamination of neutral particles derived from the plasma is one of the most critical issues that needs to be resolved. In this paper, the BRDF was assumed, and the total amount of stray light and the absorbed laser energy profile on the beam dump were evaluated.

  2. Thermal-Hydraulic Performance of Scrubbing Nozzle Used for CFVS

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Chul; Lee, Doo Yong; Jung, Woo Young; Lee, Jong Chan; Kim, Gyu Tae [FNC TECH, Yongin (Korea, Republic of)

    2016-05-15

    A Containment Filtered Venting System (CFVS) is the most interested device to mitigate a threat against containment integrity under the severe accident of nuclear power plant by venting with the filtration of the fission products. FNC technology and partners have been developed the self-priming scrubbing nozzle used for the CFVS which is based on the venturi effect. The thermal-hydraulic performances such as passive scrubbing water suction as well as pressure drop across the nozzle have been tested under various thermal-hydraulic conditions. The two types of test section have been built for testing the thermal-hydraulic performance of the self-priming scrubbing nozzle. Through the visualization loop, the liquid suction performance through the slit, pressure drop across the nozzle are measured. The passive water suction flow through the suction slit at the throat is important parameter to define the scrubbing performance of the self-priming scrubbing nozzle. The water suction flow is increased with the increase of the overhead water level at the same inlet gas flow. It is not so much changed with the change of inlet gas flow at the overhead water level.

  3. Conceptual Design for a Dual-Bell Rocket Nozzle System Using a NASA F-15 Airplane as the Flight Testbed

    Science.gov (United States)

    Jones, Daniel S.; Ruf, Joseph H.; Bui, Trong T.; Martinez, Martel; St. John, Clinton W.

    2014-01-01

    The dual-bell rocket nozzle was first proposed in 1949, offering a potential improvement in rocket nozzle performance over the conventional-bell nozzle. Despite the performance advantages that have been predicted, both analytically and through static test data, the dual-bell nozzle has still not been adequately tested in a relevant flight environment. In 2013 a proposal was constructed that offered a National Aeronautics and Space Administration (NASA) F-15 airplane as the flight testbed, with the plan to operate a dual-bell rocket nozzle during captive-carried flight. If implemented, this capability will permit nozzle operation into an external flow field similar to that of a launch vehicle, and facilitate an improved understanding of dual-bell nozzle plume sensitivity to external flow-field effects. More importantly, this flight testbed can be utilized to help quantify the performance benefit with the dual-bell nozzle, as well as to advance its technology readiness level. Toward this ultimate goal, this report provides plans for future flights to quantify the external flow field of the airplane near the nozzle experiment, as well as details on the conceptual design for the dual-bell nozzle cold-flow propellant feed system integration within the NASA F-15 Propulsion Flight Test Fixture. The current study shows that this concept of flight research is feasible, and could result in valuable flight data for the dual-bell nozzle.

  4. A CFD-based aerodynamic design procedure for hypersonic wind-tunnel nozzles

    Science.gov (United States)

    Korte, John J.

    1993-01-01

    A new procedure which unifies the best of current classical design practices, computational fluid dynamics (CFD), and optimization procedures is demonstrated for designing the aerodynamic lines of hypersonic wind-tunnel nozzles. The new procedure can be used to design hypersonic wind tunnel nozzles with thick boundary layers where the classical design procedure has been shown to break down. An efficient CFD code, which solves the parabolized Navier-Stokes (PNS) equations using an explicit upwind algorithm, is coupled to a least-squares (LS) optimization procedure. A LS problem is formulated to minimize the difference between the computed flow field and the objective function, consisting of the centerline Mach number distribution and the exit Mach number and flow angle profiles. The aerodynamic lines of the nozzle are defined using a cubic spline, the slopes of which are optimized with the design procedure. The advantages of the new procedure are that it allows full use of powerful CFD codes in the design process, solves an optimization problem to determine the new contour, can be used to design new nozzles or improve sections of existing nozzles, and automatically compensates the nozzle contour for viscous effects as part of the unified design procedure. The new procedure is demonstrated by designing two Mach 15, a Mach 12, and a Mach 18 helium nozzles. The flexibility of the procedure is demonstrated by designing the two Mach 15 nozzles using different constraints, the first nozzle for a fixed length and exit diameter and the second nozzle for a fixed length and throat diameter. The computed flow field for the Mach 15 least squares parabolized Navier-Stokes (LS/PNS) designed nozzle is compared with the classically designed nozzle and demonstrates a significant improvement in the flow expansion process and uniform core region.

  5. Numerical simulations on increasing turbojet engines exhaust mixture ratio using fluidic chevrons

    Directory of Open Access Journals (Sweden)

    Adrian GRUZEA

    2017-06-01

    Full Text Available This paper refers to some aspects regarding the terms “chevron” and “fluidic chevron” and to the process of increasing the jet engines exhaust mixing rate towards achieving noise reduction. One of the noise reduction methods consists in covering the high velocity main flow with a secondary one, having a much lower velocity, similar to the turbofan engines. The fluidic chevrons try to accomplish these requirements, being used just in particular moments of the flight. This study will be based on numerical simulations carried using the commercial software ANSYS. The geometry used will the based on the micro jet engine JetCat P80, equipping the turbines laboratory from the Faculty of Aerospace Engineering. A research based on the measured geometric, gasodynamic and cinematic parameters will be carried varying the mass flow and keeping the immersion angle constant. As a result of these simulations we’ll observe the influence of the mentioned parameters on the jet’s flow field.

  6. The modelling of an SF6 arc in a supersonic nozzle: II. Current zero behaviour of the nozzle arc

    International Nuclear Information System (INIS)

    Zhang, Q; Liu, J; Yan, J D; Fang, M T C

    2016-01-01

    The present work (part II) forms the second part of an investigation into the behaviour of SF 6 nozzle arc. It is concerned with the aerodynamic and electrical behaviour of a transient nozzle arc under a current ramp specified by a rate of current decay (d i /d t ) before current zero and a voltage ramp (d V /d t ) after current zero. The five flow models used in part I [1] for cold gas flow and DC nozzle arcs have been applied to study the transient arc at three stagnation pressures ( P 0 ) and two values of d i /d t for the current ramp, representing a wide range of arcing conditions. An analysis of the physical mechanisms encompassed in each flow model is given with an emphasis on the adequacy of a particular model in describing the rapidly varying arc around current zero. The critical rate of rise of recovery voltage (RRRV) is found computationally and compared with test results of Benenson et al [2]. For transient nozzle arcs, the RRRV is proportional to the square of P 0 , rather than to the square root of P 0 for DC nozzle arcs. The physical mechanisms responsible for the strong dependence of RRRV on P 0 have been investigated. The relative merits of the flow models employed are discussed. (paper)

  7. Control of Surge in Centrifugal Compressor by Using a Nozzle Injection System: Universality in Optimal Position of Injection Nozzle

    Directory of Open Access Journals (Sweden)

    Toshiyuki Hirano

    2012-01-01

    Full Text Available The passive control method for surge and rotating stall in centrifugal compressors by using a nozzle injection system was proposed to extend the stable operating range to the low flow rate. A part of the flow at the scroll outlet of a compressor was recirculated to an injection nozzle installed on the inner wall of the suction pipe of the compressor through the bypass pipe and injected to the impeller inlet. Two types of compressors were tested at the rotational speeds of 50,000 rpm and 60,000 rpm with the parameter of the circumferential position of the injection nozzle. The present experimental results revealed that the optimum circumferential position, which most effectively reduced the flow rate for the surge inception, existed at the opposite side of the tongue of the scroll against the rotational axis and did not depend on the compressor system and the rotational speeds.

  8. Transient Side Load Analysis of Out-of-Round Film-Cooled Nozzle Extensions

    Science.gov (United States)

    Wang, Ten-See; Lin, Jeff; Ruf, Joe; Guidos, Mike

    2012-01-01

    There was interest in understanding the impact of out-of-round nozzle extension on the nozzle side load during transient startup operations. The out-of-round nozzle extension could be the result of asymmetric internal stresses, deformation induced by previous tests, and asymmetric loads induced by hardware attached to the nozzle. The objective of this study was therefore to computationally investigate the effect of out-of-round nozzle extension on the nozzle side loads during an engine startup transient. The rocket engine studied encompasses a regeneratively cooled chamber and nozzle, along with a film cooled nozzle extension. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and transient inlet boundary flow properties derived from an engine system simulation. Six three-dimensional cases were performed with the out-of-roundness achieved by three different degrees of ovalization, elongated on lateral y and z axes: one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The results show that the separation line jump was the primary source of the peak side loads. Comparing to the peak side load of the perfectly round nozzle, the peak side loads increased for the slightly and more ovalized nozzle extensions, and either increased or decreased for the two significantly ovalized nozzle extensions. A theory based on the counteraction of the flow destabilizing effect of an exacerbated asymmetrical flow caused by a lower degree of ovalization, and the flow stabilizing effect of a more symmetrical flow, created also by ovalization, is presented to explain the observations obtained in this effort.

  9. Injection and spray characteristics of a variable orifice nozzle applied the jerk type fuel injection pump for DI diesel engine; Jerk shiki nenryo funsha pump wo mochiita kahen funko nozzle no funsha funmu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, T; Matsui, K; Iwasaki, T; Kobayashi, T [Zexel Corp., Tokyo (Japan); Matsumoto, Y [The University of Tokyo, Tokyo (Japan)

    1997-10-01

    A Variable Orifice Nozzle (VON) by changing a cross-sectional area of the nozzle injection hole, for improving a rate of injection and injection duration, has been developed to study its injection and spray characteristics. The nozzle geometry was optimized to analyze a nozzle internal flow by computational method. Results show that, injection and spray pattern responded to the nozzle orifice cross-sectional area which is changing larger to smaller in the part load range. This results suggest to contribute a combustion improvement which decreasing NOx and soot. 14 refs., 10 figs.

  10. Interpretation and significance of reverse chevron-shaped markings on fracture surfaces of API X100 pipeline steels

    International Nuclear Information System (INIS)

    Sowards, Jeffrey W.; McCowan, Chris N.; Drexler, Elizabeth S.

    2012-01-01

    Highlights: ► We investigated fractures of X100 steel linepine produced during fracture mechanics testing. ► Fractures exhibited a unique chevron pattern that points in the direction of crack propagation. ► A qualitative model is proposed to explain the fracture pattern formation. ► Findings indicate that careful interpretation of ductile material fractures is necessary. - Abstract: Fracture surfaces of X100 pipeline steels were examined with optical and electron microscopy after crack tip opening angle fracture testing. Some fracture surfaces exhibited chevron-shaped fracture patterns that are markedly different from classic chevron fracture. The chevron-shaped markings on the X100 fracture surfaces point in the direction of crack growth, rather than towards the location of fracture initiation, as observed in classic cases of chevron fracture. Existing models, predicting formation of chevron fracture patterns, do not explain the fracture behavior observed for X100 steel. A mechanism is proposed where reverse chevron-shaped patterns are developed due to the shape of the crack front itself. The chevron shape forms as a result of crack tunneling, and the overall pattern is developed on the fracture surface due to intermittent crack growth, resulting in alternating regions (bands) of fast fracture and slower, more ductile fracture. The contrast between these bands of alternating fracture defines the chevron. Care should be taken during interpretation of intermittent chevron markings on fractures of ductile materials, as they may point away from rather than towards the origin of fracture.

  11. Numerical Analysis on Effects of Positioning and Height of the Contoured Endwall on the Three-Dimensional Flow in an Annular Turbine Nozzle Guide Vane Cascade

    International Nuclear Information System (INIS)

    Lee, Wu Sang; Kim, Dae Hyun; Min, Jae Hong; Chung Jin Taek

    2007-01-01

    Endwall losses contribute significantly to the overall losses in modern turbomachinery, especially when aerodynamic airfoil load and pressure ratio are increased. Hence, reducing the extend and intensity of the secondary flow structures helps to enhance overall efficiency. From the large range of viable approaches, a promising combination positioning and height of endwall contouring was chosen. The objective of this study is to document the three-dimensional flow in a turbine cascade in terms of streamwise vorticity, total pressure loss distribution and static pressure distribution on the endwall and blade surface and to propose an appropriate positioning and height of the endwall contouring which show best secondary, overall loss reduction among the simulated endwall. The flow through the gas turbine were numerically analyzed using three dimensional Navier-Stroke equations with a commercial CFD code ANSYS CFX-10. The result shows that the overall loss is reduced near the flat endwall rather than contoured endwall, and the case of contoured endwall installed at 30% from leading edge with height of 25% for span showed best performance

  12. Influence of throttling of the heavy fraction on the uranium isotope separation in the separation nozzle

    International Nuclear Information System (INIS)

    Bley, P.; Ehrfeld, W.; Heiden, U.

    1978-04-01

    In a separation nozzle cascade for enrichment of U-235 the cut of the separation elements is adjusted by throttling the heavy fraction. This control process influences directly the flow properties in the nozzle and may noticeably change its separation characteristics. This paper deals with an experimental investigation of the throttling effect on the separation and control characteristics of the separation nozzle operated with a H 2 /UF 6 mixture. In consideration of the extremely small characteristic dimensions of commercial separation nozzle elements the influence of manufacturing tolerances on the characteristics of the throttled nozzle was analysed in detail. It appears, that the elementary effect of isotope separation increases by throttling of the heavy fraction up to 5% without changing the optimum operating conditions. This increase of the elementary effect is not only obtained for separation nozzles with zero tolerances but also for separation nozzles having finite tolerances of the skimmer position. Tolerances of the nozzle width, however, become increasingly detrimental, when the heavy fraction is throttled. Regarding the control characteristics of the separation nozzle it was found out, that the UF 6 -cut of the throttled nozzle reacts more sensitively to alterations of the operating pressures and less sensitively to alterations of the UF 6 -concentration of the process gas mixture. (orig.) [de

  13. Thrust Augmentation by Airframe-Integrated Linear-Spike Nozzle Concept for High-Speed Aircraft

    Directory of Open Access Journals (Sweden)

    Hidemi Takahashi

    2018-02-01

    Full Text Available The airframe-integrated linear-spike nozzle concept applied to an external nozzle for high-speed aircraft was evaluated with regard to the thrust augmentation capability and the trim balance. The main focus was on the vehicle aftbody. The baseline airframe geometry was first premised to be a hypersonic waverider design. The baseline aftbody case had an external nozzle comprised of a simple divergent nozzle and was hypothetically replaced with linear-spike external nozzle configurations. Performance evaluation was mainly conducted by considering the nozzle thrust generated by the pressure distribution on the external nozzle surface at the aftbody portion calculated by computer simulation at a given cruise condition with zero angle of attack. The thrust performance showed that the proposed linear-spike external nozzle concept was beneficial in thrust enhancement compared to the baseline geometry because the design of the proposed concept had a compression wall for the exhaust flow, which resulted in increasing the wall pressure. The configuration with the boattail and the angled inner nozzle exhibited further improvement in thrust performance. The trim balance evaluation showed that the aerodynamic center location appeared as acceptable. Thus, benefits were obtained by employing the airframe-integrated linear-spike external nozzle concept.

  14. Performance of a chevron steam dryer for removal of lead-bismuth droplets

    International Nuclear Information System (INIS)

    Dostal, Vaclav; Yusibani, Elin; Takahashi, Minoru

    2005-01-01

    An analysis was performed of a chevron type steam dryer with a trap for the removal of lead-bismuth droplets from steam leaving the Water Boiling Direct Contact Lead or Lead-Bismuth Cooled Reactor. The Lagrangian method was used and is described here. The steam flow field was developed using a CFD code FrontFlow/Red. The simulated dryer performance results were compared to a simple theoretical model from literature. The simulation shown that droplets down to 6 microns in diameter can be completely removed by the steam dryer, which is better than reported earlier in literature. A discrepancy with the theoretical model was found for larger droplets (5 to 10 microns in diameter), where the theoretical model predicted lower removal efficiency. The discrepancy is attributed to be installation of the trap, which is not included in this theoretical model. Some droplets of 1 and 0.5 microns were removed in the dryer as well, which indicates the potential for the fine droplet removal if the trap design is carefully optimized. The investigation of the effect of initial droplet velocity shown that the removal efficiency increases with the increase of the positive velocity components. For larger droplets the effect of initial velocity was found to be minuscule. (author)

  15. Effects of injection nozzle exit width on rotating detonation engine

    Science.gov (United States)

    Sun, Jian; Zhou, Jin; Liu, Shijie; Lin, Zhiyong; Cai, Jianhua

    2017-11-01

    A series of numerical simulations of RDE modeling real injection nozzles with different exit widths are performed in this paper. The effects of nozzle exit width on chamber inlet state, plenum flowfield and detonation propagation are analyzed. The results are compared with that using an ideal injection model. Although the ideal injection model is a good approximation method to model RDE inlet, the two-dimensional effects of real nozzles are ignored in the ideal injection model so that some complicated phenomena such as the reflected waves caused by the nozzle walls and the reversed flow into the nozzles can not be modeled accurately. Additionally, the ideal injection model overpredicts the block ratio. In all the cases that stabilize at one-wave mode, the block ratio increases as the nozzle exit width gets smaller. The dual-wave mode case also has a relatively high block ratio. A pressure oscillation in the plenum with the same main frequency with the rotating detonation wave is observed. A parameter σ is applied to describe the non-uniformity in the plenum. σ increases as the nozzle exit width gets larger. Under some condition, the heat release on the interface of fresh premixed gas layer and detonation products can be strong enough to induce a new detonation wave. A spontaneous mode-transition process is observed for the smallest exit width case. Due to the detonation products existing in the premixed gas layer before the detonation wave, the detonation wave will propagate through reactants and products alternately, and therefore its strength will vary with time, especially near the chamber inlet. This tendency gets weaker as the injection nozzle exit width increases.

  16. Injection nozzle for a turbomachine

    Science.gov (United States)

    Uhm, Jong Ho; Johnson, Thomas Edward; Kim, Kwanwoo

    2012-09-11

    A turbomachine includes a compressor, a combustor operatively connected to the compressor, an end cover mounted to the combustor, and an injection nozzle assembly operatively connected to the combustor. The injection nozzle assembly includes a first end portion that extends to a second end portion, and a plurality of tube elements provided at the second end portion. Each of the plurality of tube elements defining a fluid passage includes a body having a first end section that extends to a second end section. The second end section projects beyond the second end portion of the injection nozzle assembly.

  17. Airfoil nozzle and shroud assembly

    Science.gov (United States)

    Shaffer, J.E.; Norton, P.F.

    1997-06-03

    An airfoil and nozzle assembly are disclosed including an outer shroud having a plurality of vane members attached to an inner surface and having a cantilevered end. The assembly further includes a inner shroud being formed by a plurality of segments. Each of the segments having a first end and a second end and having a recess positioned in each of the ends. The cantilevered end of the vane member being positioned in the recess. The airfoil and nozzle assembly being made from a material having a lower rate of thermal expansion than that of the components to which the airfoil and nozzle assembly is attached. 5 figs.

  18. Trailing edge cooling using angled impingement on surface enhanced with cast chevron arrangements

    Science.gov (United States)

    Lee, Ching-Pang; Heneveld, Benjamin E.; Brown, Glenn E.; Klinger, Jill

    2015-05-26

    A gas turbine engine component, including: a pressure side (12) having an interior surface (34); a suction side (14) having an interior surface (36); a trailing edge portion (30); and a plurality of suction side and pressure side impingement orifices (24) disposed in the trailing edge portion (30). Each suction side impingement orifice is configured to direct an impingement jet (48) at an acute angle (52) onto a target area (60) that encompasses a tip (140) of a chevron (122) within a chevron arrangement (120) formed in the suction side interior surface. Each pressure side impingement orifice is configured to direct an impingement jet at an acute angle onto an elongated target area that encompasses a tip of a chevron within a chevron arrangement formed in the pressure side interior surface.

  19. Phased Array Noise Source Localization Measurements of an F404 Nozzle Plume at Both Full and Model Scale

    Science.gov (United States)

    Podboy, Gary G.; Bridges, James E.; Henderson, Brenda S.

    2010-01-01

    A 48-microphone planar phased array system was used to acquire jet noise source localization data on both a full-scale F404-GE-F400 engine and on a 1/4th scale model of a F400 series nozzle. The full-scale engine test data show the location of the dominant noise sources in the jet plume as a function of frequency for the engine in both baseline (no chevron) and chevron configurations. Data are presented for the engine operating both with and without afterburners. Based on lessons learned during this test, a set of recommendations are provided regarding how the phased array measurement system could be modified in order to obtain more useful acoustic source localization data on high-performance military engines in the future. The data obtained on the 1/4th scale F400 series nozzle provide useful insights regarding the full-scale engine jet noise source mechanisms, and document some of the differences associated with testing at model-scale versus fullscale.

  20. Proposed Flight Research of a Dual-Bell Rocket Nozzle Using the NASA F-15 Airplane

    Science.gov (United States)

    Jones, Daniel S.; Bui, Trong T.; Ruf, Joseph H.

    2013-01-01

    For more than a half-century, several types of altitude-compensating rocket nozzles have been proposed and analyzed, but very few have been adequately tested in a relevant flight environment. One type of altitude-compensating nozzle is the dual-bell rocket nozzle, which was first introduced into literature in 1949. Despite the performance advantages that have been predicted, both analytically and through static test data, the dual-bell nozzle has still not been adequately tested in a relevant flight environment. This paper proposes a method for conducting testing and research with a dual-bell rocket nozzle in a flight environment. We propose to leverage the existing NASA F-15 airplane and Propulsion Flight Test Fixture as the flight testbed, with the dual-bell nozzle operating during captive-carried flights, and with the nozzle subjected to a local flow field similar to that of a launch vehicle. The primary objective of this effort is not only to advance the technology readiness level of the dual-bell nozzle, but also to gain a greater understanding of the nozzle mode transitional sensitivity to local flow-field effects, and to quantify the performance benefits with this technology. The predicted performance benefits are significant, and may result in reducing the cost of delivering payloads to low-Earth orbit.

  1. Modelling of hydrothermal characteristics of centrifugal nozzles

    International Nuclear Information System (INIS)

    Yarkho, A.A.; Omelchenko, M.P.; Borshchev, V.A.

    1990-01-01

    Presented for the first time is a method of recalculating the hydrothermal characteristics of centrifugal nozzles obtained in laboratory conditions for full-scale nozzles. From the experimental hydrothermal characteristics of nozzles observed in the laboratory it is allowed to calculate the hydrothermal characteristics of any other centrifugal nozzle whose diameter and dimensionless geometric characteristic are known

  2. The Investigation of the Cavitation Phenomenon in the Laval Nozzle with Full and Partial Surface Wetting

    Directory of Open Access Journals (Sweden)

    Jablonská Jana

    2017-04-01

    Full Text Available The article deals with the cavitation phenomenon affected by full and partial wetting of the wall. For the numerical computation of flow in the Laval nozzle the Schnerr-Sauer cavitation model was tested and was used for cavitation research of flow within the nozzle considering partial surface wetting. The coefficient of wetting for various materials was determined using experimental, theoretical and numerical methods of fluid flow due to partial surface wetting.

  3. Bottom nozzle of a LWR fuel assembly

    International Nuclear Information System (INIS)

    Leroux, J.C.

    1991-01-01

    The bottom nozzle consists of a transverse element in form of box having a bending resistant grid structure which has an outer peripheral frame of cross-section corresponding to that of the fuel assembly and which has walls defining large cells. The transverse element has a retainer plate with a regular array of openings. The retainer plate is fixed above and parallel to the grid structure with a spacing in order to form, between the grid structure and the retainer plate a free space for tranquil flow of cooling water and for debris collection [fr

  4. Airfoil shape for a turbine nozzle

    Science.gov (United States)

    Burdgick, Steven Sebastian; Patik, Joseph Francis; Itzel, Gary Michael

    2002-01-01

    A first-stage nozzle vane includes an airfoil having a profile according to Table I. The annulus profile of the hot gas path is defined in conjunction with the airfoil profile and the profile of the inner and outer walls by the Cartesian coordinate values given in Tables I and II, respectively. The airfoil is a three-dimensional bowed design, both in the airfoil body and in the trailing edge. The airfoil is steam and air-cooled by flowing cooling mediums through cavities extending in the vane between inner and outer walls.

  5. Characterization of kink actuators as compared to traditional chevron shaped Bent-Beam electrothermal actuators

    KAUST Repository

    Rawashdeh, E.; Karam, A.; Foulds, Ian G.

    2012-01-01

    This paper compares the design and performance of kink actuators, a modified version of the bent-beam thermal actuator, to the standard chevron-shaped designs. A variety of kink and chevron actuator designs were fabricated from polysilicon. While the actuators were electrically probed, these designs were tested using a probe station connected to a National Instruments (NI) controller that uses LabVIEW to extract the displacement results via image processing. The displacement results were then used to validate the thermal-electric-structural simulations produced by COMSOL. These results, in turn, were used to extract the stiffness for both actuator types. The data extracted show that chevron actuators can have larger stiffness values with increasing offsets, but at the cost of lower amplification factors. In contrast, kink actuators showed a constant stiffness value equivalent to the chevron actuator with the highest amplification factor. The kink actuator also had larger amplification factors than chevrons at all designs tested. Therefore, kink actuators are capable of longer throws at lower power levels than the standard chevron designs.

  6. Characterization of kink actuators as compared to traditional chevron shaped Bent-Beam electrothermal actuators

    KAUST Repository

    Rawashdeh, E.

    2012-07-06

    This paper compares the design and performance of kink actuators, a modified version of the bent-beam thermal actuator, to the standard chevron-shaped designs. A variety of kink and chevron actuator designs were fabricated from polysilicon. While the actuators were electrically probed, these designs were tested using a probe station connected to a National Instruments (NI) controller that uses LabVIEW to extract the displacement results via image processing. The displacement results were then used to validate the thermal-electric-structural simulations produced by COMSOL. These results, in turn, were used to extract the stiffness for both actuator types. The data extracted show that chevron actuators can have larger stiffness values with increasing offsets, but at the cost of lower amplification factors. In contrast, kink actuators showed a constant stiffness value equivalent to the chevron actuator with the highest amplification factor. The kink actuator also had larger amplification factors than chevrons at all designs tested. Therefore, kink actuators are capable of longer throws at lower power levels than the standard chevron designs.

  7. Equivalent nozzle in thermomechanical problems

    International Nuclear Information System (INIS)

    Cesari, F.

    1977-01-01

    When analyzing nuclear vessels, it is most important to study the behavior of the nozzle cylinder-cylinder intersection. For the elastic field, this analysis in three dimensions is quite easy using the method of finite elements. The same analysis in the non-linear field becomes difficult for designs in 3-D. It is therefore necessary to resolve a nozzle in two dimensions equivalent to a 3-D nozzle. The purpose of the present work is to find an equivalent nozzle both with a mechanical and thermal load. This has been achieved by the analysis in three dimensions of a nozzle and a nozzle cylinder-sphere intersection, of a different radius. The equivalent nozzle will be a nozzle with a sphere radius in a given ratio to the radius of a cylinder; thus, the maximum equivalent stress is the same in both 2-D and 3-D. The nozzle examined derived from the intersection of a cylindrical vessel of radius R=191.4 mm and thickness T=6.7 mm with a cylindrical nozzle of radius r=24.675 mm and thickness t=1.350 mm, for which the experimental results for an internal pressure load are known. The structure was subdivided into 96 finite, three-dimensional and isoparametric elements with 60 degrees of freedom and 661 total nodes. Both the analysis with a mechanical load as well as the analysis with a thermal load were carried out on this structure according to the Bersafe system. The thermal load consisted of a transient typical of an accident occurring in a sodium-cooled fast reactor, with a peak of the temperature (540 0 C) for the sodium inside the vessel with an insulating argon temperature constant at 525 0 C. The maximum value of the equivalent tension was found in the internal area at the union towards the vessel side. The analysis of the nozzle in 2-D consists in schematizing the structure as a cylinder-sphere intersection, where the sphere has a given relation to the

  8. Numerical Simulation of Twin Nozzle Injectors

    OpenAIRE

    Milak, Dino

    2015-01-01

    Fuel injectors for marine applications have traditionally utilized nozzles with symmetric equispaced orifice configuration. But in light of the new marine emission legislations the twin nozzle concept has arisen. The twin nozzle differs from the conventional configuration by utilizing two closely spaced orifices to substitute each orifice in the conventional nozzle. Injector manufacturers regard twin nozzle injectors as a promising approach to facilitate stable spray patterns independent of t...

  9. Hypersonic nozzle/afterbody CFD code validation. I - Experimental measurements

    Science.gov (United States)

    Spaid, Frank W.; Keener, Earl R.

    1993-01-01

    This study was conducted to obtain a detailed experimental description of the flow field created by the interaction of a single-expansion-ramp-nozzle flow with a hypersonic external stream. Data were obtained from a generic nozzle/afterbody model in the 3.5-Foot Hypersonic Wind Tunnel of the NASA Ames Research Center in a cooperative experimental program involving Ames and the McDonnell Douglas Research Laboratories. This paper presents experimental results consisting primarily of surveys obtained with a five-hole total-pressure/flow-direction probe and a total-temperature probe. These surveys were obtained in the flow field created by the interaction between the underexpanded jet plume and the external flow.

  10. SHINE Tritium Nozzle Design: Activity 6, Task 1 Report

    Energy Technology Data Exchange (ETDEWEB)

    Okhuysen, Brett S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pulliam, Elias Noel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-05

    In FY14, we studied the qualitative and quantitative behavior of a SHINE/PNL tritium nozzle under varying operating conditions. The result is an understanding of the nozzle’s performance in terms of important flow features that manifest themselves under different parametric profiles. In FY15, we will consider nozzle design with a focus on nozzle geometry and integration. From FY14 work, we will understand how the SHINE/PNL nozzle behaves under different operating scenarios. The first task for FY15 is to evaluate the FY14 model as a predictor of the actual flow. Considering different geometries is more time-intensive than parameter studies, therefore we recommend considering any relevant flow features that were not included in the FY14 model. In the absence of experimental data, it is particularly important to consider any sources of heat in the domain or boundary conditions that may affect the flow and incorporate these into the simulation if they are significant. Additionally, any geometric features of the beamline segment should be added to the model such as the orifice plate. The FY14 model works with hydrogen. An improvement that can be made for FY15 is to develop CFD properties for tritium and incorporate those properties into the new models.

  11. Radiant Energy Measurements from a Scaled Jet Engine Axisymmetric Exhaust Nozzle for a Baseline Code Validation Case

    Science.gov (United States)

    Baumeister, Joseph F.

    1994-01-01

    A non-flowing, electrically heated test rig was developed to verify computer codes that calculate radiant energy propagation from nozzle geometries that represent aircraft propulsion nozzle systems. Since there are a variety of analysis tools used to evaluate thermal radiation propagation from partially enclosed nozzle surfaces, an experimental benchmark test case was developed for code comparison. This paper briefly describes the nozzle test rig and the developed analytical nozzle geometry used to compare the experimental and predicted thermal radiation results. A major objective of this effort was to make available the experimental results and the analytical model in a format to facilitate conversion to existing computer code formats. For code validation purposes this nozzle geometry represents one validation case for one set of analysis conditions. Since each computer code has advantages and disadvantages based on scope, requirements, and desired accuracy, the usefulness of this single nozzle baseline validation case can be limited for some code comparisons.

  12. Numerical study on drop formation through a micro nozzle

    International Nuclear Information System (INIS)

    Kim, Sung Il; Son, Gi Hun

    2005-01-01

    The drop ejection process from a micro nozzle is investigated by numerically solving the conservation equations for mass and momentum. The liquid-gas interface is tracked by a level set method which is extended for two-fluid flows with irregular solid boundaries. Based on the numerical results, the liquid jet breaking and droplet formation behavior is found to depend strongly on the pulse type of forcing pressure and the contact angle at the gas-liquid-solid interline. The negative pressure forcing can be used to control the formation of satelite droplets. Also, various nozzle shapes are tested to investigate their effect on droplet formation

  13. Annular Internal-External-Expansion Rocket Nozzles for Large Booster Applications

    Science.gov (United States)

    Connors, James F.; Cubbison, Robert W.; Mitchell, Glenn A.

    1961-01-01

    For large-thrust booster applications, annular rocket nozzles employing both internal and external expansion are investigated. In these nozzles, free-stream air flows through the center as well as around the outside of the exiting jet. Flaps for deflecting the rocket exhaust are incorporated on the external-expansion surface for thrust-vector control. In order to define nozzle off-design performance, thrust vectoring effectiveness, and external stream effects, an experimental investigation was conducted on two annular nozzles with area ratios of 15 and 25 at Mach 0, 2, and 3 in the Lewis 10- by 10-foot wind tunnel. Air, pressurized to 600 pounds per square inch absolute, was used to simulate the exhaust flow. For a nozzle-pressure-ratio range of 40 to 1000, the ratio of actual to ideal thrust was essentially constant at 0.98 for both nozzles. Compared with conventional convergent-divergent configurations on hypothetical boost missions, the performance gains of the annular nozzle could yield significant orbital payload increases (possibly 8 to 17 percent). A single flap on the external-expansion surface of the area-ratio-25 annular nozzle produced a side force equal to 4 percent of the axial force with no measurable loss in axial thrust.

  14. Modified computation of the nozzle damping coefficient in solid rocket motors

    Science.gov (United States)

    Liu, Peijin; Wang, Muxin; Yang, Wenjing; Gupta, Vikrant; Guan, Yu; Li, Larry K. B.

    2018-02-01

    In solid rocket motors, the bulk advection of acoustic energy out of the nozzle constitutes a significant source of damping and can thus influence the thermoacoustic stability of the system. In this paper, we propose and test a modified version of a historically accepted method of calculating the nozzle damping coefficient. Building on previous work, we separate the nozzle from the combustor, but compute the acoustic admittance at the nozzle entry using the linearized Euler equations (LEEs) rather than with short nozzle theory. We compute the combustor's acoustic modes also with the LEEs, taking the nozzle admittance as the boundary condition at the combustor exit while accounting for the mean flow field in the combustor using an analytical solution to Taylor-Culick flow. We then compute the nozzle damping coefficient via a balance of the unsteady energy flux through the nozzle. Compared with established methods, the proposed method offers competitive accuracy at reduced computational costs, helping to improve predictions of thermoacoustic instability in solid rocket motors.

  15. Optimization design of energy deposition on single expansion ramp nozzle

    Science.gov (United States)

    Ju, Shengjun; Yan, Chao; Wang, Xiaoyong; Qin, Yupei; Ye, Zhifei

    2017-11-01

    Optimization design has been widely used in the aerodynamic design process of scramjets. The single expansion ramp nozzle is an important component for scramjets to produces most of thrust force. A new concept of increasing the aerodynamics of the scramjet nozzle with energy deposition is presented. The essence of the method is to create a heated region in the inner flow field of the scramjet nozzle. In the current study, the two-dimensional coupled implicit compressible Reynolds Averaged Navier-Stokes and Menter's shear stress transport turbulence model have been applied to numerically simulate the flow fields of the single expansion ramp nozzle with and without energy deposition. The numerical results show that the proposal of energy deposition can be an effective method to increase force characteristics of the scramjet nozzle, the thrust coefficient CT increase by 6.94% and lift coefficient CN decrease by 26.89%. Further, the non-dominated sorting genetic algorithm coupled with the Radial Basis Function neural network surrogate model has been employed to determine optimum location and density of the energy deposition. The thrust coefficient CT and lift coefficient CN are selected as objective functions, and the sampling points are obtained numerically by using a Latin hypercube design method. The optimized thrust coefficient CT further increase by 1.94%, meanwhile, the optimized lift coefficient CN further decrease by 15.02% respectively. At the same time, the optimized performances are in good and reasonable agreement with the numerical predictions. The findings suggest that scramjet nozzle design and performance can benefit from the application of energy deposition.

  16. Influence of Diesel Nozzle Geometry on Cavitation Using Eulerian Multi-Fluid Method

    Institute of Scientific and Technical Information of China (English)

    张军; 杜青; 杨延相

    2010-01-01

    Dependent on automatically generated unstructured grids, a comprehensive computational fluid dynamics(CFD)numerical simulation is performed to analyze the influence of nozzle geometry on the internal flow characteristics of a multi-hole diesel injector with the multi-phase flow model based on Eulerian multi-fluid method.The diesel components in nozzle are considered as two continuous phases, diesel liquid and diesel vapor respectively.Considering that both of them are fully coupled and interpenetrated, sepa...

  17. Device to enrich uranium using the separation nozzle method

    International Nuclear Information System (INIS)

    Wenzel, W.

    1984-01-01

    Separation nozzle units, coolers and the radial-flow compressor are integrated in such manner that the volume of the device is reduced and the efficiency is increased. The radial-flow compressor that is placed in a central and axial position in the cylindrical casing of the tank is concentrically surrounded by the other elements, which are arranged in a way that regular maintenance becomes possible without difficulties. The detailed description is supplemented by drawings. (ori./PW)

  18. [The minimally invasive Chevron and Akin osteotomy (MICA)].

    Science.gov (United States)

    Altenberger, Sebastian; Kriegelstein, Stefanie; Gottschalk, Oliver; Dreyer, Florian; Mehlhorn, Alexander; Röser, Anke; Walther, Markus

    2018-04-18

    Percutaneous correction of a hallux valgus deformity with or without transfer metatarsalgia. Hallux valgus deformity up to 20° intermetatarsal angle, without instability of the first tarsometatarsal joint. Symptomatic arthritis of the first metatarsophalangeal joint, as well as instability of the first tarsometatarsal joint. Percutaneous performed osteotomy of the distal metatarsal 1 in combination with a medial closing wedge osteotomy of the proximal phalanx of the first toe. The use of a postoperative shoe with a rigid sole allows adapted weight bearing in the first 6 weeks. Active and passive mobilization can start immediately after surgery. The method is very effective to treat even severe deformities with or without metatarsalgia. The amount of correction is similar to open procedures. We recommend cadaver training to become familiar with this technique. Thus, complications such as nerve, vessel or tendon injuries can be avoided. The intraoperative radiation exposure remains significantly elevated even for experienced surgeons. In addition to the aesthetic benefits, there is less soft tissue traumatization compared to conventional open procedures. There is no need of bloodlessness. The minimally invasive Chevron and Akin osteotomy is a safe and powerful technique for the treatment of hallux valgus deformity.

  19. Kabob report. Pt. 3. Chevron plant largest in Canada

    Energy Technology Data Exchange (ETDEWEB)

    1971-01-18

    Canada's largest fully integrated primary natural- gas processing and sulfur recovery plant is heading for physical completion by mid-summer of 1971. The Ralph M. Parsons Construction Co. of Canada Ltd., contractor for the S. Kaybob Beaverhill Lake Unit No. 3 gas-processing plant, to be operated by Chevron Standard Ltd., estimates completion by June 30. After that the $80 million complex will have tests and running in time. With any reasonable luck, it should be fully on stream by late summer. Preliminary construction on the 200-acre site started in Jan. 1969 with clearing and contouring of the main plant and sulfur storage sites. Initial rough grading started in the early summer, after spring breakup was over. Delivery of most of the big items was made by rail because the local secondary roads were inadequate for them. Concrete has been a large item. The contractor has its own batch plant on the site for the estimated 28,000 cu yd which will be needed for the whole job. Dominating the construction site from the start has been the high sulfur plant stack, first of the major items to be finished. It will serve to dispose of effluent from the largest sulfur recovery unit in Canada. It is 465 ft high, one of the largest in Alberta, and a significant contribution to pollution control and environmental protection.

  20. Electro–optic response in thin smectic C* film with chevron structures

    International Nuclear Information System (INIS)

    Kudreyko, Aleksey A; Migranov, Nail G; Migranova, Dana N

    2016-01-01

    The effects in electrostatic models of chevron surface-stabilized ferroelectric liquid crystals are investigated through numerical modeling. To study smectic C* director distribution within the cell, we consider two nonlinear approaches: the chevron interface does not interplay with the electric field; the electric field interplays with the chevron interface. The obtained results of the director field distribution are compared with the earlier linearized studies. We find that whether or not the electric field interplays with the chevron interface, the electro–optic response requires a generalized approach for its description. The threshold electric field, which is necessary for switching between two stable director states in the chevron cell is evaluated. This study suggests that, in many cases of practical interest, electro–optic response to the electric field and the threshold electric field can be precisely estimated. We argue that, beside being numerically efficient, our approach provides a convenient and a novel standpoint for looking at the electro–optic response problem. (paper)

  1. Improved Nozzle Testing Techniques in Transonic Flow

    Science.gov (United States)

    1975-10-01

    axiale) et comporte un barreau dynamometrique equips de jauges de contrainte. La canne est solidaire d’un ensemble balance-bloc d’alimentation des...s a l’aide de capteurs produisant un signal ilectrique : Pressions : capteurs ä jauges Temperatures : thermocouples Chromel-Alumel - Efforts...barreau dynamometrique a jauges de contrainte. Les signaux eiectriques sont acquis et traites par la chaine automatique de la soufflerie. Les mesures

  2. 77 FR 66597 - Chevron U.S.A. Inc.; Application for Blanket Authorization To Export Previously Imported...

    Science.gov (United States)

    2012-11-06

    ..., California. Chevron Global Gas is a division of Chevron that engages in the global business of marketing and.... Department of Energy (FE-34), Office of Oil and Gas Global Security and Supply, Office of Fossil Energy... CONTACT: Larine Moore or Beverly Howard, U.S. Department of Energy (FE-34), Office of Oil and Gas Global...

  3. Direct Numerical Simulation of Acoustic Noise Generation from the Nozzle Wall of a Hypersonic Wind Tunnel

    Science.gov (United States)

    Huang, Junji; Duan, Lian; Choudhari, Meelan M.

    2017-01-01

    The acoustic radiation from the turbulent boundary layer on the nozzle wall of a Mach 6 Ludwieg Tube is simulated using Direct Numerical Simulations (DNS), with the flow conditions falling within the operational range of the Mach 6 Hypersonic Ludwieg Tube, Braunschweig (HLB). The mean and turbulence statistics of the nozzle-wall boundary layer show good agreement with those predicted by Pate's correlation and Reynolds Averaged Navier-Stokes (RANS) computations. The rms pressure fluctuation P'(rms)/T(w) plateaus in the freestream core of the nozzle. The intensity of the freestream noise within the nozzle is approximately 20% higher than that radiated from a single at pate with a similar freestream Mach number, potentially because of the contributions to the acoustic radiation from multiple azimuthal segments of the nozzle wall.

  4. Computational Fluid Dynamics Modeling of a Supersonic Nozzle and Integration into a Variable Cycle Engine Model

    Science.gov (United States)

    Connolly, Joseph W.; Friedlander, David; Kopasakis, George

    2015-01-01

    This paper covers the development of an integrated nonlinear dynamic simulation for a variable cycle turbofan engine and nozzle that can be integrated with an overall vehicle Aero-Propulso-Servo-Elastic (APSE) model. A previously developed variable cycle turbofan engine model is used for this study and is enhanced here to include variable guide vanes allowing for operation across the supersonic flight regime. The primary focus of this study is to improve the fidelity of the model's thrust response by replacing the simple choked flow equation convergent-divergent nozzle model with a MacCormack method based quasi-1D model. The dynamic response of the nozzle model using the MacCormack method is verified by comparing it against a model of the nozzle using the conservation element/solution element method. A methodology is also presented for the integration of the MacCormack nozzle model with the variable cycle engine.

  5. The influence of collapse wall on self-excited oscillation pulsed jet nozzle performance

    International Nuclear Information System (INIS)

    Fang, Z L; Kang, Y; Yang, X F; Yuan, B; Li, D

    2012-01-01

    The self-excited oscillation pulsed jet (SOPJ) is widely used owing to its simple structure and good separation of pressure source and system. The structure of nozzle is one of the main factors that influence the performance of the SOPJ nozzle. Upper collapse wall and lower collapse wall is important to the formation and transmission of eddy in oscillation cavity. In this paper, the influence of collapse wall on SOPJ nozzle was analyzed by numerical simulation. The LES algorithm was used to simulate the flow of different combinations of collapse wall. The result showed that when both collapse walls are of the same type, the SOPJ nozzle will have a good performance; the influence of upper collapse wall is more obvious than lower one; model of two-semi-circle upper collapse wall is the first choice when we design SOPJ nozzle.

  6. Turbomachine combustor nozzle including a monolithic nozzle component and method of forming the same

    Science.gov (United States)

    Stoia, Lucas John; Melton, Patrick Benedict; Johnson, Thomas Edward; Stevenson, Christian Xavier; Vanselow, John Drake; Westmoreland, James Harold

    2016-02-23

    A turbomachine combustor nozzle includes a monolithic nozzle component having a plate element and a plurality of nozzle elements. Each of the plurality of nozzle elements includes a first end extending from the plate element to a second end. The plate element and plurality of nozzle elements are formed as a unitary component. A plate member is joined with the nozzle component. The plate member includes an outer edge that defines first and second surfaces and a plurality of openings extending between the first and second surfaces. The plurality of openings are configured and disposed to register with and receive the second end of corresponding ones of the plurality of nozzle elements.

  7. Analysis of film cooling in rocket nozzles

    Science.gov (United States)

    Woodbury, Keith A.

    1993-01-01

    This report summarizes the findings on the NASA contract NAG8-212, Task No. 3. The overall project consists of three tasks, all of which have been successfully completed. In addition, some supporting supplemental work, not required by the contract, has been performed and is documented herein. Task 1 involved the modification of the wall functions in the code FDNS (Finite Difference Navier-Stokes) to use a Reynolds Analogy-based method. This task was completed in August, 1992. Task 2 involved the verification of the code against experimentally available data. The data chosen for comparison was from an experiment involving the injection of helium from a wall jet. Results obtained in completing this task also show the sensitivity of the FDNS code to unknown conditions at the injection slot. This task was completed in September, 1992. Task 3 required the computation of the flow of hot exhaust gases through the P&W 40K subscale nozzle. Computations were performed both with and without film coolant injection. This task was completed in July, 1993. The FDNS program tends to overpredict heat fluxes, but, with suitable modeling of backside cooling, may give reasonable wall temperature predictions. For film cooling in the P&W 40K calorimeter subscale nozzle, the average wall temperature is reduced from 1750R to about 1050R by the film cooling. The average wall heat flux is reduced by a factor of 3.

  8. The separation nozzle process for uranium isotope enrichment

    International Nuclear Information System (INIS)

    Becker, E.W.

    1977-01-01

    In the separation nozzle process, uranium isotope separation is brought about by the mass dependence of the centrifugal forces in a curved flow of a UF 6 /H 2 -mixture. Due to the large excess in hydrogen the high ration of UF 6 flow velocity to thermal velocity required for an effective isotope separation is obtained at relatively low expansion ratios and, accordingly, with relatively low gas-dynamic losses. As the optimum Reynolds number of the curved jet is comparatively low and a high absolute pressure is essential for economic reasons, the characteristic dimensions of the nozzle systems are made as small as possible. For commercial application in the near future systems involving mechanical jet deflection were developed. However, promising results were also obtained with separation nozzle systems generating a streamline curvature by the interaction of opposed jets. Most of the development work has been done at the Nuclear Research Center of Karlsruhe. Since 1970 the German company STEAG has been involved in the commercial implementation of the process. Two industrial-scale separative stages were tested successfully. This work constitutes the basis of planning of a separation nozzle demonstration plant to be built in Brazil

  9. Process for manufacturing separating nozzles

    International Nuclear Information System (INIS)

    Bier, W.; Linder, G.; Mayer, E.

    1979-01-01

    The final form of the basic body and the unit consisting of the nozzle and peeling orifice provides immovable fixing of these parts. Surfaces of various components can then be milled, using milling tools, in one operation. Assembly can be made automatic. (DG) [de

  10. Nozzle for electric dispersion reactor

    Science.gov (United States)

    Sisson, W.G.; Basaran, O.A.; Harris, M.T.

    1995-11-07

    A nozzle for an electric dispersion reactor includes two concentric electrodes, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode. 4 figs.

  11. Heat exchanger nozzle stresses due to pipe vibration

    International Nuclear Information System (INIS)

    Wolgemuth, G.A.

    1983-01-01

    A large diameter pipe in a heavy water production plant was excited into a low frequency vibration due to void collapse of the pipe contents at a sharp vertical drop in the pipe run. Fears that this vibration would fatigue the inlet nozzle to the heat exchanger prompted the introduction of a flow of cold water into the pipe to prevent the two-phase flow from developing but at the cost of reduced heat exchanger efficiency. An investigation was carried out to determine the stress levels in the nozzle with the quenching flow off and suggest means of reducing them if excessive. A finite element dynamic simulation of the pipe run was performed to determine the likely mode shapes. This information was used to optimize the placement of velocity probes on the pipe. Field measurements of vibration were taken for several operating conditions. This data was analyzed and the results used to refine the support stiffness used in the finite element simulation. The finite element model was then used to predict the nozzle forces and moments. In turn this data was used to determine the local stresses in the nozzle. The ASME Section III code was used to determine the allowable fully reversing stresses for the unit in question. It was found that the endurance limit of 83 MPa was exceeded in the analysis only when using the most conservative estimates for each uncertainty. It was recommended that if the safety factor was not deemed high enough, the nozzle should be built up with a reinforcing pad no thicker than 12 mm

  12. RSRM Nozzle-to-Case Joint J-leg Development

    Science.gov (United States)

    Albrechtsen, Kevin U.; Eddy, Norman F.; Ewing, Mark E.; McGuire, John R.

    2003-01-01

    Since the beginning of the Space Shuttle Reusable Solid Rocket Motor (RSRM) program, nozzle-to-case joint polysulfide adhesive gas paths have occurred on several flight motors. These gas paths have allowed hot motor gases to reach the wiper O-ring. Even though these motors continue to fly safely with this condition, a desire was to reduce such occurrences. The RSRM currently uses a J-leg joint configuration on case field joints and igniter inner and outer joints. The J-leg joint configuration has been successfully demonstrated on numerous RSRM flight and static test motors, eliminating hot gas intrusion to the critical O-ring seals on these joints. Using the proven technology demonstrated on the case field joints and igniter joints, a nozzle-to-case joint J-leg design was developed for implementation on RSRM flight motors. This configuration provides an interference fit with nozzle fixed housing phenolics at assembly, with a series of pressurization gaps incorporated outboard of the joint mating surface to aid in joint pressurization and to eliminate any circumferential flow in this region. The joint insulation is bonded to the nozzle phenolics using the same pressure sensitive adhesive used in the case field joints and igniter joints. An enhancement to the nozzle-to-case joint J-leg configuration is the implementation of a carbon rope thermal barrier. The thermal barrier is located downstream of the joint bondline and is positioned within the joint in a manner where any hot gas intrusion into the joint passes through the thermal barrier, reducing gas temperatures to a level that would not affect O-rings downstream of the thermal barrier. This paper discusses the processes used in reaching a final nozzle-to-case joint J-leg design, provides structural and thermal results in support of the design, and identifies fabrication techniques and demonstrations used in arriving at the final configuration.

  13. CFD Analysis of Nozzle Exit Position Effect in Ejector Gas Removal System in Geothermal Power Plant

    Directory of Open Access Journals (Sweden)

    Setyo Nugroho

    2015-06-01

    Full Text Available The single stage ejector is used to extract the Non CondensableGas (NCG in the condenser using the working principle of the Venturi tube. Three dimensional computational simulation of the ejector according to the operating conditions was conducted to determine the flow in the ejector. Motive steam entering through the convergent – divergent nozzle with increasing flow velocity so that the low pressure exist around the nozzle. Comparison is done also in a two dimensional simulation to know the differences occurring phenomena and flow inside ejector. Different simulation results obtained between two dimensional and three dimensional simulation. Reverse flow which occurs in the mixing chamber made the static pressure in the area has increased dramatically. Then the variation performed on Exit Nozzle Position (NXP to determine the changes of the flow of the NCG and the vacuum level of the ejector. Keywords: Ejector, NCG, CFD, Compressible flow.

  14. Internal performance of a 10 deg conical plug nozzle with a multispoke primary and translating external shroud

    Science.gov (United States)

    Bresnahan, D. L.

    1972-01-01

    An experimental investigation was conducted in a nozzle static test facility to determine the performance characteristics of a cold-flow, 21.59-centimeter-diameter plug nozzle with a multispoke primary. Two multispoke primary nozzles, a 12-spoke and a 24-spoke, were tested and compared with an annular plug nozzle. The supersonic cruise configurations for both spoke primaries performed about the same, with a gross thrust coefficient of 0.974, a decrease of approximately 1.5 percent from the reference nozzle. The takeoff configuration for the 12-spoke primary had a gross thrust coefficient of 0.957, a decrease of 1.5 percent from the reference nozzle, and the 24-spoke primary had a gross thrust coefficient of 0.95.

  15. Performance Prediction of Darrieus-Type Hydroturbine with Inlet Nozzle Operated in Open Water Channels

    Science.gov (United States)

    Nakashima, K.; Watanabe, S.; Matsushita, D.; Tsuda, S.; Furukawa, A.

    2016-11-01

    Small hydropower is one of the renewable energies and is expected to be effectively used for local supply of electricity. We have developed Darrieus-type hydro-turbine systems, and among them, the Darrieus-turbine with a weir and a nozzle installed upstream of turbine is, so far, in success to obtain more output power by gathering all water into the turbine. However, there can several cases exist, in which installing the weir covering all the flow channel width is unrealistic, and in such cases, the turbine should be put alone in open channels without upstream weir. Since the output power is very small in such a utilization of small hydropower, it is important to derive more power for the cost reduction. In the present study, we parametrically investigate the preferable shape of the inlet nozzle for the Darrieus-type hydroturbine operated in an open flow channel. Experimental investigation is carried out in the open channel in our lab. Tested inlet nozzles are composed of two flat plates with the various nozzle converging angles and nozzle outlet (runner inlet) widths with the nozzle inlet width kept constant. As a result, the turbine with the nozzles having large converging angle and wide outlet width generates higher power. Two-dimensional unsteady numerical simulation is also carried out to qualitatively understand the flow mechanism leading to the better performance of turbine. Since the depth, the width and the flow rate in the real open flow channels are different from place to place and, in some cases from time to time, it is also important to predict the onsite performance of the hydroturbine from the lab experiment at planning stage. One-dimensional stream-tube model is developed for this purpose, in which the Darrieus-type hydroturbine with the inlet nozzle is considered as an actuator-disk modelled based on our experimental and numerical results.

  16. Evaluation of flip-flop jet nozzles for use as practical excitation devices

    Science.gov (United States)

    Raman, Ganesh; Rice, Edward J.; Cornelius, David M.

    1994-01-01

    This paper describes the flowfield characteristics of the flip-flop jet nozzle and the potential for using this nozzle as a practical excitation device. It appears from the existing body of published information that there is a lack of data on the parameters affecting the operation of such nozzles and on the mechanism of operation of these nozzles. An attempt is made in the present work to study the important parameters affecting the operation and performance of a flip-flop jet nozzle. Measurements were carried out to systematically assess the effect of varying the nozzle pressure ratio (NPR) as well as the length and volume of the feedback tube on the frequency of oscillation of this device. Flow visualization was used to obtain a better understanding of the jet flowfield and of the processes occurring within the feedback tube. The frequency of oscillation of the flip-flop jet depended significantly on the feedback tube length and volume as well as on the nozzle pressure ratio. In contrast, the coherent velocity perturbation levels did not depend on the above mentioned parameters. The data presented in this paper would be useful for modeling such flip-flop excitation devices that are potentially useful for controlling practical shear flows.

  17. Osteotomia em Chevron modificada: análise preliminar do comportamento baropodométrico Modified Chevron osteotomy: preliminary analysis of baropodometric behavior

    Directory of Open Access Journals (Sweden)

    Juliana Motta Costa

    2010-01-01

    Full Text Available OBJETIVO: Avaliar as características clínicas e baropodométricas da marcha de indivíduos com Hálux Valgo após a osteotomia em Chevron modificada, isolada ou em associação com a osteotomia de Weil. MÉTODOS: FORAM avaliados, antes e três meses após a cirurgia, 27 pés com deformidade leve e moderada. A avaliação clínica incluiu a pontuação da AOFAS e medidas radiográficas. A avaliação baropodométrica foi realizada através da Plataforma Emed-at. As variáveis Pico de Pressão, Integral Pressão-Tempo e Carga Relativa foram calculadas em 10 regiões: calcanhar, mediopé, 1-5º metatársicos, hálux, 2º, 3-5º dedos. RESULTADOS: Após a cirurgia houve aumento na pontuação da AOFAS e redução dos parâmetros radiográficos. A avaliação baropodométrica, após osteotomia em Chevron isolada, demonstrou redução da pressão e da força sob o 1º metatársico e hálux, assim como, aumento dessas variáveis nos metatársicos centrais e laterais. Após a osteotomia em Chevron/Weil ocorreram alterações significativas apenas na região do hálux e dos dedos. CONCLUSÃO: Em curto prazo, a técnica em Chevron modificada promoveu melhora das condições clínicas e dos parâmetros radiográficos. Em relação a avaliação baropodométrica constatou-se uma transferência de cargas da região medial para lateral do antepé, possivelmente pelo curto período de pós-operatório.OBJECTIVE: To evaluate the clinical and baropodometric characteristics of the gaits of individuals with a hallux valgus deformity after modified Chevron osteotomy, in isolation or in association with the Weil osteotomy. METHODS: Foot evaluation happened before and three months after surgery analyzing 27 mildly and moderately deformed feet. The clinical evaluation included the AOFAS score and radiographic measurements. The baropodometric evaluation was done with the Emed-at platform. Peak of Pressure, Pressure-Time Integral and Relative Load were calculated in

  18. Feedback mechanism for smart nozzles and nebulizers

    Science.gov (United States)

    Montaser, Akbar [Potomac, MD; Jorabchi, Kaveh [Arlington, VA; Kahen, Kaveh [Kleinburg, CA

    2009-01-27

    Nozzles and nebulizers able to produce aerosol with optimum and reproducible quality based on feedback information obtained using laser imaging techniques. Two laser-based imaging techniques based on particle image velocimetry (PTV) and optical patternation map and contrast size and velocity distributions for indirect and direct pneumatic nebulizations in plasma spectrometry. Two pulses from thin laser sheet with known time difference illuminate droplets flow field. Charge coupled device (CCL)) captures scattering of laser light from droplets, providing two instantaneous particle images. Pointwise cross-correlation of corresponding images yields two-dimensional velocity map of aerosol velocity field. For droplet size distribution studies, solution is doped with fluorescent dye and both laser induced florescence (LIF) and Mie scattering images are captured simultaneously by two CCDs with the same field of view. Ratio of LIF/Mie images provides relative droplet size information, then scaled by point calibration method via phase Doppler particle analyzer.

  19. Chemical processes in the turbine and exhaust nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Lukachko, S P; Waitz, I A [Massachusetts Inst. of Tech., Cambridge, MA (United States). Aero-Environmental Lab.; Miake-Lye, R C; Brown, R C; Anderson, M R [Aerodyne Research, Inc., Billerica, MA (United States); Dawes, W N [University Engineering Dept., Cambridge (United Kingdom). Whittle Lab.

    1998-12-31

    The objective is to establish an understanding of primary pollutant, trace species, and aerosol chemical evolution as engine exhaust travels through the nonuniform, unsteady flow fields of the turbine and exhaust nozzle. An understanding of such processes is necessary to provide accurate inputs for plume-wake modeling efforts and is therefore a critical element in an assessment of the atmospheric effects of both current and future aircraft. To perform these studies, a numerical tool was developed combining the calculation of chemical kinetics and one-, two-, or three-dimensional (1-D, 2-D, 3-D) Reynolds-averaged flow equations. Using a chemistry model that includes HO{sub x}, NO{sub y}, SO{sub x}, and CO{sub x} reactions, several 1-D parametric analyses were conducted for the entire turbine and exhaust nozzle flow path of a typical advanced subsonic engine to understand the effects of various flow and chemistry uncertainties on a baseline 1-D result. These calculations were also used to determine parametric criteria for judging 1-D, 2-D, and 3-D modeling requirements as well as to provide information about chemical speciation at the nozzle exit plane. (author) 9 refs.

  20. Chemical processes in the turbine and exhaust nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Lukachko, S.P.; Waitz, I.A. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Aero-Environmental Lab.; Miake-Lye, R.C.; Brown, R.C.; Anderson, M.R. [Aerodyne Research, Inc., Billerica, MA (United States); Dawes, W.N. [University Engineering Dept., Cambridge (United Kingdom). Whittle Lab.

    1997-12-31

    The objective is to establish an understanding of primary pollutant, trace species, and aerosol chemical evolution as engine exhaust travels through the nonuniform, unsteady flow fields of the turbine and exhaust nozzle. An understanding of such processes is necessary to provide accurate inputs for plume-wake modeling efforts and is therefore a critical element in an assessment of the atmospheric effects of both current and future aircraft. To perform these studies, a numerical tool was developed combining the calculation of chemical kinetics and one-, two-, or three-dimensional (1-D, 2-D, 3-D) Reynolds-averaged flow equations. Using a chemistry model that includes HO{sub x}, NO{sub y}, SO{sub x}, and CO{sub x} reactions, several 1-D parametric analyses were conducted for the entire turbine and exhaust nozzle flow path of a typical advanced subsonic engine to understand the effects of various flow and chemistry uncertainties on a baseline 1-D result. These calculations were also used to determine parametric criteria for judging 1-D, 2-D, and 3-D modeling requirements as well as to provide information about chemical speciation at the nozzle exit plane. (author) 9 refs.

  1. The inverted chevron plot measured by NMR relaxation reveals a native-like unfolding intermediate in acyl-CoA binding protein

    DEFF Research Database (Denmark)

    Teilum, Kaare; Poulsen, F. M.; Akke, M.

    2006-01-01

    those from stopped-flow kinetics and define an "inverted chevron" plot. The combination of NMR relaxation and stopped-flow kinetic measurements allowed determination of k f and k u in the range from 0.48 M GuHCl to 1.28 M GuHCl. Individually, the stopped-flow and NMR data fit two-state models...... for folding. However, although the values of k f determined by the two methods agree, the values of k u do not. As a result, a combined analysis of all data does not comply with a two-state model but indicates that an unfolding intermediate exists on the native side of the dominant energy barrier...

  2. Experiments on the spray nozzles used in the pressurizer of power reactor

    International Nuclear Information System (INIS)

    Diao Wentang

    1989-04-01

    The spray nozzle, which is used in the pressurizer of pressurized water reactor system, usually uses a less differential pressure between the reactor inlet and outlet as the spray drive pressure, but its flow rate is relatively larger. It is difficult to obtain a optimum spray performance of such a nozzle. The experimental results of five types of twenty seven spray nozzles in different structures and sizes with the range of the spray drive pressure from 0.127 to 0.245 MPa and the flow rates from 5 to 50 t/h are given. The main factors affecting spray performances and their distribution characteristics have been found. And some relatively suitable spray structures have been recommended, which can be used as references for improving the spray nozzles used in the pressurizers of existing PWRs or of the PWRs to be built

  3. Method and equipment of separation of gaseous and vaporous materials, particularly isotopes, with separation nozzles

    International Nuclear Information System (INIS)

    Becker, E.W.; Eisenbeiss, G.; Ehrfeld, W.

    1975-01-01

    The invention improves on the already known separation nozzle method by the two following steps: 1) The partial flows produced within the cascade with various shares of additional gas are introduced into the separating nozzle systems in such a manner that with regard to the additional gas, a molar fraction gradient is created which is in the opposite direction to the gradient created by the separation process. 2) The partial flows produced within the cascade with various compositions of the mixture of substances to be separated are introduced into the separating nozzle systems in such a manner that regarding the substances to be separated, a molar fraction gradient is created which is in the same direction as the molar fraction gradient formed by the separation process. Both measures can be separately applied or in combination with one another; flowsheets of the invented cascade circuits and separating nozzle systems are given. (GG/LH) [de

  4. Experimental investigation on motive nozzle throat diameter for an ejector expansion refrigeration system

    International Nuclear Information System (INIS)

    Bilir Sag, Nagihan; Ersoy, H. Kursad

    2016-01-01

    Highlights: • Effects of nozzle throat diameter and its location on performance were investigated. • The nozzle has an optimum throat diameter under the experiment condition. • The maximum performance has been achieved by using optimum nozzle throat diameter. • The variation of nozzle throat diameter with condenser water inlet temperature was examined. • Motive nozzle has no optimum position in the ejector refrigeration system. - Abstract: In this study, ejector was used to reduce throttling losses in a vapour compression refrigeration system. Effects on system performance of throat diameter and position of motive nozzle of ejector were investigated experimentally. An ejector was designed based on the established mathematical model and manufactured. The experiments were carried out by using different primary nozzle throat diameters. The experiments were further conducted by changing condenser water inlet temperature, which is one of the external parameters. The experimental results of the ejector system and those of the classic system were compared under same external operating conditions and for the same cooling capacity. In order to obtain same external operating conditions in both systems, the inlet conditions of the brine supplied to the evaporator and inlet water conditions (flow rate and temperature) to the condenser were kept constant. Maximum performance was obtained when the primary nozzle throat diameter was 2.3 mm within the areas considered in this study. When compared, it was experimentally determined that the ejector system that uses the optimum motive nozzle throat diameter exhibits higher COP than the classic system by 5–13%. Furthermore, it was found that the variation of coefficient of performance based on position of motive nozzle in two-phase ejector expander refrigeration cycle is lower than 1%.

  5. Comparison of the Modified McBride Procedure and the Distal Chevron Osteotomy for Mild to Moderate Hallux Valgus.

    Science.gov (United States)

    Choi, Gi Won; Kim, Hak Jun; Kim, Taik Seon; Chun, Sung Kwang; Kim, Tae Wan; Lee, Yong In; Kim, Kyoung Ho

    2016-01-01

    Distal metatarsal osteotomy and the modified McBride procedure have each been used for the treatment of mild to moderate hallux valgus. However, few studies have compared the results of these 2 procedures for mild to moderate hallux valgus. The purpose of the present study was to compare the results of distal chevron osteotomy and the modified McBride procedure for treatment of mild to moderate hallux valgus according to the severity of the deformity. We analyzed the data from 45 patients (49.5%; 48 feet [49.0%]), who had undergone an isolated modified McBride procedure (McBride group), and 46 patients (50.5%; 50 feet [51.0%]), who had a distal chevron osteotomy (chevron group). We subdivided each group into those with mild and moderate deformity and compared the clinical and radiologic outcomes between the groups in relation to the severity of the deformity. The improvements in the American Orthopaedic Foot and Ankle Society scale score and the visual analog scale for pain were significantly better for the chevron group for both mild and moderate deformity. The chevron group experienced significantly greater correction in the hallux valgus angle and intermetatarsal angle for both mild and moderate deformity. The chevron group experienced a significantly greater decrease in the grade of sesamoid displacement for patients with moderate deformity. The McBride group had a greater risk of recurrence than did the chevron group for moderate deformity (odds ratio 14.00, 95% confidence interval 3.91 to 50.06, p hallux valgus recurrence than did the distal chevron group. Therefore, we recommend distal chevron osteotomy rather than a modified McBride procedure for the treatment of mild and moderate hallux valgus. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  6. Outcomes in chevron osteotomy for Hallux Valgus in a large cohort

    NARCIS (Netherlands)

    van Groningen, B. (Bart); M.C.M. (Marieke) van der Steen,; M. Reijman (Max); Bos, J. (Janneke); Hendriks, J.G.E. (Johannes G.E.)

    2016-01-01

    textabstractClinical and radiological related outcomes have been reported for Chevron osteotomy as correction for mild to moderate hallux valgus, but only for relatively small patient series. Moreover, evaluation of the patient's point of view has mostly been conducted by means of more

  7. Effective hydraulic resistance of actuator nozzle generating a periodic jet

    Czech Academy of Sciences Publication Activity Database

    Tesař, Václav

    2012-01-01

    Roč. 179, JUN 2012 (2012), s. 211-222 ISSN 0924-4247 R&D Projects: GA ČR(CZ) GCP101/11/J019; GA TA ČR(CZ) TA02020795 Institutional research plan: CEZ:AV0Z20760514 Keywords : nozzle * periodic flow * compressibility Subject RIV: BK - Fluid Dynamics Impact factor: 1.841, year: 2012 http://www.sciencedirect.com/science/article/pii/S0924424712001781

  8. RANS Analyses of Turbofan Nozzles with Internal Wedge Deflectors for Noise Reduction

    Science.gov (United States)

    DeBonis, James R.

    2009-01-01

    Computational fluid dynamics (CFD) was used to evaluate the flow field and thrust performance of a promising concept for reducing the noise at take-off of dual-stream turbofan nozzles. The concept, offset stream technology, reduces the jet noise observed on the ground by diverting (offsetting) a portion of the fan flow below the core flow, thickening and lengthening this layer between the high-velocity core flow and the ground observers. In this study a wedge placed in the internal fan stream is used as the diverter. Wind, a Reynolds averaged Navier-Stokes (RANS) code, was used to analyze the flow field of the exhaust plume and to calculate nozzle performance. Results showed that the wedge diverts all of the fan flow to the lower side of the nozzle, and the turbulent kinetic energy on the observer side of the nozzle is reduced. This reduction in turbulent kinetic energy should correspond to a reduction in noise. However, because all of the fan flow is diverted, the upper portion of the core flow is exposed to the freestream, and the turbulent kinetic energy on the upper side of the nozzle is increased, creating an unintended noise source. The blockage due to the wedge reduces the fan mass flow proportional to its blockage, and the overall thrust is consequently reduced. The CFD predictions are in very good agreement with experimental flow field data, demonstrating that RANS CFD can accurately predict the velocity and turbulent kinetic energy fields. While this initial design of a large scale wedge nozzle did not meet noise reduction or thrust goals, this study identified areas for improvement and demonstrated that RANS CFD can be used to improve the concept.

  9. Acoustic and aerodynamic performance investigation of inverted velocity profile coannular plug nozzles. [variable cycle engines

    Science.gov (United States)

    Knott, P. R.; Blozy, J. T.; Staid, P. S.

    1981-01-01

    The results of model scale parametric static and wind tunnel aerodynamic performance tests on unsuppressed coannular plug nozzle configurations with inverted velocity profile are discussed. The nozzle configurations are high-radius-ratio coannular plug nozzles applicable to dual-stream exhaust systems typical of a variable cycle engine for Advanced Supersonic Transport application. In all, seven acoustic models and eight aerodynamic performance models were tested. The nozzle geometric variables included outer stream radius ratio, inner stream to outer stream ratio, and inner stream plug shape. When compared to a conical nozzle at the same specific thrust, the results of the static acoustic tests with the coannular nozzles showed noise reductions of up to 7 PNdB. Extensive data analysis showed that the overall acoustic results can be well correlated using the mixed stream velocity and the mixed stream density. Results also showed that suppression levels are geometry and flow regulation dependent with the outer stream radius ratio, inner stream-to-outer stream velocity ratio and inner stream velocity ratio and inner stream plug shape, as the primary suppression parameters. In addition, high-radius ratio coannular plug nozzles were found to yield shock associated noise level reductions relative to a conical nozzle. The wind tunnel aerodynamic tests showed that static and simulated flight thrust coefficient at typical takeoff conditions are quite good - up to 0.98 at static conditions and 0.974 at a takeoff Mach number of 0.36. At low inner stream flow conditions significant thrust loss was observed. Using an inner stream conical plug resulted in 1% to 2% higher performance levels than nozzle geometries using a bent inner plug.

  10. The effects of finite rate chemical processes on high enthalpy nozzle performance - A comparison between SPARK and SEAGULL

    Science.gov (United States)

    Carpenter, M. H.

    1988-01-01

    The generalized chemistry version of the computer code SPARK is extended to include two higher-order numerical schemes, yielding fourth-order spatial accuracy for the inviscid terms. The new and old formulations are used to study the influences of finite rate chemical processes on nozzle performance. A determination is made of the computationally optimum reaction scheme for use in high-enthalpy nozzles. Finite rate calculations are compared with the frozen and equilibrium limits to assess the validity of each formulation. In addition, the finite rate SPARK results are compared with the constant ratio of specific heats (gamma) SEAGULL code, to determine its accuracy in variable gamma flow situations. Finally, the higher-order SPARK code is used to calculate nozzle flows having species stratification. Flame quenching occurs at low nozzle pressures, while for high pressures, significant burning continues in the nozzle.

  11. Effect of shocks on film cooling of a full scale turbojet exhaust nozzle having an external expansion surface

    Science.gov (United States)

    Straight, D. M.

    1979-01-01

    Cooling is one of the critical technologies for efficient design of exhaust nozzles, especially for the developing technology of nonaxisymmetric (2D) nozzles for future aircraft applications. Several promising 2D nozzle designs have external expansion surfaces which need to be cooled. Engine data are scarce, however, on nozzle cooling effectiveness in the supersonic flow environment (with shocks) that exists along external expansion surfaces. This paper will present experimental film cooling data obtained during exploratory testing with an axisymmetric plug nozzle having external expansion and installed on an afterburning turbojet engine in an altitude test facility. The data obtained shows that the shocks and local hot gas stream conditions have a marked effect on film cooling effectiveness. An existing film cooling correlation is adequate at some operating conditions but inadequate at other conditions such as in separated flow regions resulting from shock-boundary-layer interactions.

  12. SINGLE PHASE ANALYTICAL MODELS FOR TERRY TURBINE NOZZLE

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Haihua; Zhang, Hongbin; Zou, Ling; O' Brien, James

    2016-11-01

    All BWR RCIC (Reactor Core Isolation Cooling) systems and PWR AFW (Auxiliary Feed Water) systems use Terry turbine, which is composed of the wheel with turbine buckets and several groups of fixed nozzles and reversing chambers inside the turbine casing. The inlet steam is accelerated through the turbine nozzle and impacts on the wheel buckets, generating work to drive the RCIC pump. As part of the efforts to understand the unexpected “self-regulating” mode of the RCIC systems in Fukushima accidents and extend BWR RCIC and PWR AFW operational range and flexibility, mechanistic models for the Terry turbine, based on Sandia National Laboratories’ original work, has been developed and implemented in the RELAP-7 code to simulate the RCIC system. RELAP-7 is a new reactor system code currently under development with the funding support from U.S. Department of Energy. The RELAP-7 code is a fully implicit code and the preconditioned Jacobian-free Newton-Krylov (JFNK) method is used to solve the discretized nonlinear system. This paper presents a set of analytical models for simulating the flow through the Terry turbine nozzles when inlet fluid is pure steam. The implementation of the models into RELAP-7 will be briefly discussed. In the Sandia model, the turbine bucket inlet velocity is provided according to a reduced-order model, which was obtained from a large number of CFD simulations. In this work, we propose an alternative method, using an under-expanded jet model to obtain the velocity and thermodynamic conditions for the turbine bucket inlet. The models include both adiabatic expansion process inside the nozzle and free expansion process out of the nozzle to reach the ambient pressure. The combined models are able to predict the steam mass flow rate and supersonic velocity to the Terry turbine bucket entrance, which are the necessary input conditions for the Terry Turbine rotor model. The nozzle analytical models were validated with experimental data and

  13. Effect of Pressure on the Uniformity of Nozzles Transverse Distribution and Mathematical Model Development

    Directory of Open Access Journals (Sweden)

    Vladimir Višacki

    2017-01-01

    Full Text Available Timely and high-quality application of pesticides contributes to environmental protection, economical production and production of healthy food. The efficacy of pesticide application depends not only on the quality of pesticides but also the quality of the application. One of the factor that most influences the quality of applications, from the standpoint of mechanization, are nozzles. They working liquid applied on the surface the plant resulting in the same volume of pesticide is applied to the entire surface of the plants. To achieve this goal, nozzles must be performed uniform application of working liquid per unit area, or tractor sprayer working width. The variable factor in the application of pesticides may be nozzle and operating pressure. With increasing working pressure obtained smaller droplets. The paper presents test of three different nozzles. Each nozzle is characterized by a flat jet with an angle of 110° and a flow rate of 1.6 l∙min−1 at a pressure of 3 bar. Differ from each other are by the way of disintegration of the jet. Exactly this characteristic causes that with pressure change coming to changes in the uniformity of nozzles transverse distribution. So the best distribution has nozzle with a flat jet. The coefficient of variation is between roughly from 4 to 6 % at the pressure application of 2 to 4 bar. Obtained mathematical model that describes changes in the coefficient of variation depending on pressure applications can be a good basis for easy harmonization parameters in the pesticide application.

  14. Aerosol Scrubbing Performance Test for Self-Priming Scrubbing Nozzle Submerged in Water Pool

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Doo Yong; Jung, Woo Young; Lee, Hyun Chul; Lee, Jong Chan; Kim, Gyu Tae; Song, Yong Jae [FNC Technology Co., Yongin (Korea, Republic of)

    2016-10-15

    A scrubbing nozzle is one of the key components for a wet scrubber process based Containment Filtered Venting System (CFVS). As a part of a development of Korean CFVS, a self-priming scrubbing nozzle shown in Fig. 1 has been developed based on the well-known venturi scrubber concept. The thermal-hydraulic performances such as the pressure drop across the nozzle, water suction behavior and droplet generation inside throat have been tested in the non-submerged condition as well as submerged condition. The self-priming scrubbing nozzle used for the wet scrubber based CFVS has been developed, which is submerged in the water pool. When there is gas flow at the inlet of the nozzle, the pool water is passively sucked from the water suction slit. The fine droplets generated inside the throat capture the aerosol particles and is discharged into the water pool. In the water pool, the pool scrubbing happens. The aerosol scrubbing performance tests for the developed self-priming scrubbing nozzle has been conducted under the operational conditions such as different aerosol sizes, different carrier gas steam fractions, different, different pool water level and nozzle inlet pressure. The major findings are as follows. (1) Aerosol scrubbing efficiency increases with the increase of the aerosol size. (2) Aerosol scrubbing efficiency increases with the increase of the carrier gas steam fraction. (3) Aerosol scrubbing.

  15. Aerosol Scrubbing Performance Test for Self-Priming Scrubbing Nozzle Submerged in Water Pool

    International Nuclear Information System (INIS)

    Lee, Doo Yong; Jung, Woo Young; Lee, Hyun Chul; Lee, Jong Chan; Kim, Gyu Tae; Song, Yong Jae

    2016-01-01

    A scrubbing nozzle is one of the key components for a wet scrubber process based Containment Filtered Venting System (CFVS). As a part of a development of Korean CFVS, a self-priming scrubbing nozzle shown in Fig. 1 has been developed based on the well-known venturi scrubber concept. The thermal-hydraulic performances such as the pressure drop across the nozzle, water suction behavior and droplet generation inside throat have been tested in the non-submerged condition as well as submerged condition. The self-priming scrubbing nozzle used for the wet scrubber based CFVS has been developed, which is submerged in the water pool. When there is gas flow at the inlet of the nozzle, the pool water is passively sucked from the water suction slit. The fine droplets generated inside the throat capture the aerosol particles and is discharged into the water pool. In the water pool, the pool scrubbing happens. The aerosol scrubbing performance tests for the developed self-priming scrubbing nozzle has been conducted under the operational conditions such as different aerosol sizes, different carrier gas steam fractions, different, different pool water level and nozzle inlet pressure. The major findings are as follows. (1) Aerosol scrubbing efficiency increases with the increase of the aerosol size. (2) Aerosol scrubbing efficiency increases with the increase of the carrier gas steam fraction. (3) Aerosol scrubbing

  16. Variable volume combustor with pre-nozzle fuel injection system

    Science.gov (United States)

    Keener, Christopher Paul; Johnson, Thomas Edward; McConnaughhay, Johnie Franklin; Ostebee, Heath Michael

    2016-09-06

    The present application provides a combustor for use with a gas turbine engine. The combustor may include a number of fuel nozzles, a pre-nozzle fuel injection system supporting the fuel nozzles, and a linear actuator to maneuver the fuel nozzles and the pre-nozzle fuel injection system.

  17. Fractal analysis of agricultural nozzles spray

    Directory of Open Access Journals (Sweden)

    Francisco Agüera

    2012-02-01

    Full Text Available Fractal scaling of the exponential type is used to establish the cumulative volume (V distribution applied through agricultural spray nozzles in size x droplets, smaller than the characteristic size X. From exponent d, we deduced the fractal dimension (Df which measures the degree of irregularity of the medium. This property is known as 'self-similarity'. Assuming that the droplet set from a spray nozzle is self-similar, the objectives of this study were to develop a methodology for calculating a Df factor associated with a given nozzle and to determine regression coefficients in order to predict droplet spectra factors from a nozzle, taking into account its own Df and pressure operating. Based on the iterated function system, we developed an algorithm to relate nozzle types to a particular value of Df. Four nozzles and five operating pressure droplet size characteristics were measured using a Phase Doppler Particle Analyser (PDPA. The data input consisted of droplet size spectra factors derived from these measurements. Estimated Df values showed dependence on nozzle type and independence of operating pressure. We developed an exponential model based on the Df to enable us to predict droplet size spectra factors. Significant coefficients of determination were found for the fitted model. This model could prove useful as a means of comparing the behavior of nozzles which only differ in not measurable geometric parameters and it can predict droplet spectra factors of a nozzle operating under different pressures from data measured only in extreme work pressures.

  18. High Pressure Water Stripping Using Multi-Orifice Nozzles

    Science.gov (United States)

    Hoppe, David

    1999-01-01

    The use of multi-orifice rotary nozzles greatly increases the speed and stripping effectiveness of high pressure water blasting systems, but also greatly increases the complexity of selecting and optimizing the operating parameters. The rotational speed of the nozzle must be coupled with its transverse velocity as it passes across the surface of the substrate being stripped. The radial and angular positions of each orifice must be included in the analysis of the nozzle configuration. Orifices at the outer edge of the nozzle head move at a faster rate than the orifices located near the center. The energy transmitted to the surface from the impact force of the water stream from an outer orifice is therefore spread over a larger area than energy from an inner orifice. Utilizing a larger diameter orifice in the outer radial positions increases the total energy transmitted from the outer orifice to compensate for the wider distribution of energy. The total flow rate from the combination of all orifices must be monitored and should be kept below the pump capacity while choosing orifice to insert in each position. The energy distribution from the orifice pattern is further complicated since the rotary path of all the orifices in the nozzle head pass through the center section. All orifices contribute to the stripping in the center of the path while only the outer most orifice contributes to the stripping at the edge of the nozzle. Additional orifices contribute to the stripping from the outer edge toward the center section. With all these parameters to configure and each parameter change affecting the others, a computer model was developed to track and coordinate these parameters. The computer simulation graphically indicates the cumulative affect from each parameter selected. The result from the proper choices in parameters is a well designed, highly efficient stripping system. A poorly chosen set of parameters will cause the nozzle to strip aggressively in some areas

  19. Computer Graphic Design Using Auto-CAD and Plug Nozzle Research

    Science.gov (United States)

    Rogers, Rayna C.

    2004-01-01

    The purpose of creating computer generated images varies widely. They can be use for computational fluid dynamics (CFD), or as a blueprint for designing parts. The schematic that I will be working on the summer will be used to create nozzles that are a part of a larger system. At this phase in the project, the nozzles needed for the systems have been fabricated. One part of my mission is to create both three dimensional and two dimensional models on Auto-CAD 2002 of the nozzles. The research on plug nozzles will allow me to have a better understanding of how they assist in the thrust need for a missile to take off. NASA and the United States military are working together to develop a new design concept. On most missiles a convergent-divergent nozzle is used to create thrust. However, the two are looking into different concepts for the nozzle. The standard convergent-divergent nozzle forces a mixture of combustible fluids and air through a smaller area in comparison to where the combination was mixed. Once it passes through the smaller area known as A8 it comes out the end of the nozzle which is larger the first or area A9. This creates enough thrust for the mechanism whether it is an F-18 fighter jet or a missile. The A9 section of the convergent-divergent nozzle has a mechanism that controls how large A9 can be. This is needed because the pressure of the air coming out nozzle must be equal to that of the ambient pressure other wise there will be a loss of performance in the machine. The plug nozzle however does not need to have an A9 that can vary. When the air flow comes out it can automatically sense what the ambient pressure is and will adjust accordingly. The objective of this design is to create a plug nozzle that is not as complicated mechanically as it counterpart the convergent-divergent nozzle.

  20. Axisymmetric nozzles with chamfered contraction

    Czech Academy of Sciences Publication Activity Database

    Tesař, Václav

    2017-01-01

    Roč. 263, August (2017), s. 147-158 ISSN 0924-4247 Institutional support: RVO:61388998 Keywords : nozzles * chamfering * invariant Subject RIV: BK - Fluid Dynamics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.499, year: 2016 http://ac.els-cdn.com/S0924424716310329/1-s2.0-S0924424716310329-main.pdf?_tid=f953dc4c-873c-11e7-b8d0-00000aacb35d&acdnat=1503408341_51527a384c272a3c4e8f43e6046d789d

  1. Thermal-Hydraulic Integral Effect Test with the ATLS for Investigation on CEDM Penetration Nozzle Integrity

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Kyoungho; Seokcho; Park, Hyunsik; Choi, Namhyun; Park, Yusun; Kim, Jongrok; Bae, Byounguhn; Kim, Yeonsik; Choi, Kiyong; Song, Chulhwa [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    In this study, thermal-hydraulic integral effect test with the ATLAS (Advanced Thermal-Hydraulic Test Loop for Accident Simulation) was performed for simulating a failure of CEDM penetration nozzle. The main objectives of the present test were not only to provide physical insight into the system response during a failure of CEDM penetration nozzle but also to establish an integral effect test database for the validation of the safety analysis codes. Furthermore, present experimental data were utilized to resolve the safety issue raised by the PWSCC at the CEDM penetration nozzle of the YGN-3. Thermal-hydraulic integral effect test with the ATLAS was performed for simulating a failure of CEDM penetration nozzle. Failure of two penetration nozzles of the CEDM in the APR1400 was simulated. Initial and boundary conditions were determined with respect to the reference conditions of the APR1400. However, with an aim of corresponding to the YGN-3 situation, the safety injection water was supplied via CLI mode. Compared to the cold leg break SBLOCA, the consequences of the event were milder in terms of a loop seal clearance, break flow rate, collapsed water level, and PCT. This could be mainly attributed to the small break flow rate in case of the failure in the RPV upper head. Present experimental data were utilized to resolve the safety issue raised by the PWSCC at the CEDM penetration nozzle of the YGN-3.

  2. Transient Three-Dimensional Side Load Analysis of a Film Cooled Nozzle

    Science.gov (United States)

    Wang, Ten-See; Guidos, Mike

    2008-01-01

    Transient three-dimensional numerical investigations on the side load physics for an engine encompassing a film cooled nozzle extension and a regeneratively cooled thrust chamber, were performed. The objectives of this study are to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and a transient inlet history based on an engine system simulation. Ultimately, the computational results will be provided to the nozzle designers for estimating of effect of the peak side load on the nozzle structure. Computations simulating engine startup at ambient pressures corresponding to sea level and three high altitudes were performed. In addition, computations for both engine startup and shutdown transients were also performed for a stub nozzle, operating at sea level. For engine with the full nozzle extension, computational result shows starting up at sea level, the peak side load occurs when the lambda shock steps into the turbine exhaust flow, while the side load caused by the transition from free-shock separation to restricted-shock separation comes at second; and the side loads decreasing rapidly and progressively as the ambient pressure decreases. For the stub nozzle operating at sea level, the computed side loads during both startup and shutdown becomes very small due to the much reduced flow area.

  3. Black hole acoustics in the minimal geometric deformation of a de Laval nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, Roldao da [Universidade Federal do ABC-UFABC, Centro de Matematica, Computacao e Cognicao, Santo Andre (Brazil)

    2017-05-15

    The correspondence between sound waves, in a de Laval propelling nozzle, and quasinormal modes emitted by brane-world black holes deformed by a 5D bulk Weyl fluid are here explored and scrutinized. The analysis of sound waves patterns in a de Laval nozzle in the laboratory, reciprocally, is here shown to provide relevant data about the 5D bulk Weyl fluid and its on-brane projection, comprised by the minimal geometrically deformed compact stellar distribution on the brane. Acoustic perturbations of the gas fluid flow in the de Laval nozzle are proved to coincide with the quasinormal modes of black holes solutions deformed by the 5D Weyl fluid, in the geometric deformation procedure. Hence, in a phenomenological Eoetvoes-Friedmann fluid brane-world model, the realistic shape of a de Laval nozzle is derived and its consequences studied. (orig.)

  4. Cavitation inception in nozzle-plate and wire mesh pressure droppers in water and sodium

    International Nuclear Information System (INIS)

    Collinson, A.E.

    1976-01-01

    Cavitation tests on multi-hole nozzle plates and wire meshes approximately 100mm diameter in water at 20 deg C and sodium at 300 deg C are described. These pressure dropping elements were mounted in recirculating loops where cavitation was induced by gradually lowering the back-ground pressure at constant flow. Cavitation was detected acoustically using wall mounted piezoelectric microphones, the signal being displayed on a ratemeter recording individual cavitation events. For nozzle plates, cavitation started intermittently as the pressure was lowered, the noise level suddenly increasing at a critical cavitation number sigma. For meshes the intermittent region was absent. Values of sigma for nozzles and meshes were similar in water and sodium for the conditions prevailing during the tests. It was apparent that cavitation took place on the axes of vortices both in the free stream and close to nozzle curved surfaces

  5. A Comparative Study of Nozzle/Diffuser Micropumps with Novel Valves

    Directory of Open Access Journals (Sweden)

    Jin-Cherng Shyu

    2012-02-01

    Full Text Available This study conducts an experimental study concerning the improvement of nozzle/diffuser micropump design using some novel no-moving-part valves. A total of three micropumps, including two enhancement structures having two-fin or obstacle structure and one conventional micro nozzle/diffuser design, are made and tested in this study. It is found that dramatic increase of the pressure drops across the designed micro nozzles/diffusers are seen when the obstacle or fin structure is added. The resultant maximum flow rates are 47.07 mm3/s and 53.39 mm3/s, respectively, for the conventional micro nozzle/diffuser and the added two-fin structure in micro nozzle/diffuser operated at a frequency of 400 Hz. Yet the mass flow rate for two-fin design surpasses that of conventional one when the frequency is below 425 Hz but the trend is reversed with a further increase of frequency. This is because the maximum efficiency ratio improvement for added two-fin is appreciably higher than the other design at a lower operating frequency. In the meantime, despite the efficiency ratio of the obstacle structure also reveals a similar trend as that of two-fin design, its significant pressure drop (flow resistance had offset its superiority at low operating frequency, thereby leading to a lesser flow rate throughout the test range.

  6. Prediction of the Inlet Nozzle Velocity Profiles for the CANDU-6 Moderator Analysis

    International Nuclear Information System (INIS)

    Yoon, Churl; Park, Joo Hwan

    2006-01-01

    For the moderator analysis of the CANDU reactors in Korea, predicting local moderator subcooling in the Calandria vessels is one of the main concerns for the estimation of heat sink capability of moderator under LOCA transients. The moderator circulation pattern is determined by the combined forces of the inlet jet momentum and the buoyancy flow. Even though the inlet boundary condition plays an important role in determining the moderator circulations, no measured data of detailed inlet velocity profiles is available. The purpose of this study is to produce the velocity profiles at the inlet nozzles by a CFD simulation. To produce the velocity vector fields at the inlet nozzle surfaces, the internal flows in the nozzle assembly were simulated by using a commercial CFD code, CFX-5.7. In the reference, the analytical capability of CFX-5.7 had been estimated by a validation of the CFD code against available experimental data for separate flow phenomena. Various turbulence models and grid spacing had been also tested. In the following section, the interface treatment between the computational domains would be explained. In section 3, the inlet nozzle flow through the CANDU moderator nozzle assembly was predicted by using the obtained technology of the CFD simulation

  7. Pengaruh Jarak dan Posisi Nozzle terhadap Daya Turbin Pelton

    OpenAIRE

    Kurniawan, Yani; Pane, Erlanda Augupta; Ismail, Ismail

    2017-01-01

    Pelton Turbine is a turbine which use nozzle as officers the direction of a stream water in order to move around of blade turbine. The rotating of turbine blade efected by some parameters such as the distance of the nozzle, position of nozzle, diameter of nozzle, number of nozzle, and the geometry shape of the blade turbine. An experimental study to analyze the affect of distance and position nozzle to Pelton Turbine of performance. The research method used experiment parameter was position o...

  8. Pengaruh Jarak dan Posisi Nozzle Terhadap Daya Turbin Pelton

    OpenAIRE

    Yani Kurniawan; Erlanda Augupta Pane; Ismail

    2017-01-01

    Pelton Turbine is a turbine which use nozzle as officers the direction of a stream water in order to move around of blade turbine. The rotating of turbine blade efected by some parameters such as the distance of the nozzle, position of nozzle, diameter of nozzle, number of nozzle, and the geometry shape of the blade turbine. An experimental study to analyze the affect of distance and position nozzle to Pelton Turbine of performance. The research method used experiment parameter was position o...

  9. Palo Verde Unit 3 BMI nozzle modification

    International Nuclear Information System (INIS)

    Waskey, D.

    2015-01-01

    The 61 BMI (Bottom Mount Instrumentation) nozzles of the unit 3 of the Palo Verde plant have been examined through ASME Code Case N722. The nozzle 3 was the only one with leakage noted. The ultrasound testing results are characteristic of PWSCC (Primary Water Stress Corrosion Cracking). The initiation likely occurred at a weld defect which was exposed to the primary water environment resulting in PWSCC. All other nozzles (60) showed no unacceptable indications. Concerning nozzle 3 one crack in J-groove weld connected large defect to primary water. An environmental model has been used to simulate and optimize the repair. The AREVA crew was on site 18 days after contract award and the job was completed in 12 days, 30 hours ahead of baseline schedule. This series of slides describes the examination of the BMI nozzles, the repair steps, and alternative design concepts

  10. No midterm benefit from low intensity pulsed ultrasound after chevron osteotomy for hallux valgus.

    Science.gov (United States)

    Zacherl, Max; Gruber, Gerald; Radl, Roman; Rehak, Peter H; Windhager, Reinhard

    2009-08-01

    Chevron osteotomy is a widely accepted method for correction of symptomatic hallux valgus deformity. Full weight bearing in regular shoes is not recommended before 6 weeks after surgery. Low intensity pulsed ultrasound is known to stimulate bone formation leading to more stable callus and faster bony fusion. We performed a randomized, placebo-controlled, double-blinded study on 44 participants (52 feet) who underwent chevron osteotomy to evaluate the influence of daily transcutaneous low intensity pulsed ultrasound (LIPUS) treatment at the site of osteotomy. Follow-up at 6 weeks and 1 year included plain dorsoplantar radiographs, hallux-metatarsophalangeal-interphalangeal scale and a questionnaire on patient satisfaction. There was no statistical difference in any pre- or postoperative clinical features, patient satisfaction or radiographic measurements (hallux valgus angle, intermetatarsal angle, sesamoid index and metatarsal index) except for the first distal metatarsal articular angle (DMAA). The DMAA showed statistically significant (p = 0.046) relapse in the placebo group upon comparison of intraoperative radiographs after correction and fixation (5.2 degrees) and at the 6-week follow-up (10.6 degrees). Despite potential impact of LIPUS on bone formation, we found no evidence of an influence on outcome 6 weeks and 1 year after chevron osteotomy for correction of hallux valgus deformity.

  11. Standard test method for plane-strain (Chevron-Notch) fracture toughness of metallic materials

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    1.1 This test method covers the determination of plane-strain (chevron-notch) fracture toughnesses, KIv or KIvM, of metallic materials. Fracture toughness by this method is relative to a slowly advancing steady state crack initiated at a chevron-shaped notch, and propagating in a chevron-shaped ligament (Fig. 1). Some metallic materials, when tested by this method, exhibit a sporadic crack growth in which the crack front remains nearly stationary until a critical load is reached. The crack then becomes unstable and suddenly advances at high speed to the next arrest point. For these materials, this test method covers the determination of the plane-strain fracture toughness, KIvj or KIvM, relative to the crack at the points of instability. Note 1—One difference between this test method and Test Method E 399 (which measures KIc) is that Test Method E 399 centers attention on the start of crack extension from a fatigue precrack. This test method makes use of either a steady state slowly propagating crack, or a...

  12. Design and fabrication of a MEMS chevron-type thermal actuator

    Energy Technology Data Exchange (ETDEWEB)

    Baracu, Angela, E-mail: angela.baracu@imt.ro [Laboratory of Modeling, Simulation and CAD, National Institute for R and D in Microtechnologies - IMT Bucharest, 126A, Erou Iancu Nicolae Street, 077190, Bucharest, Romania and University Politehnica of Bucharest (Romania); Voicu, Rodica; Müller, Raluca; Avram, Andrei [Laboratory of Modeling, Simulation and CAD, National Institute for R and D in Microtechnologies - IMT Bucharest, 126A, Erou Iancu Nicolae Street, 077190, Bucharest (Romania); Pustan, Marius, E-mail: marius.pustan@omt.utcluj.ro; Chiorean, Radu, E-mail: marius.pustan@omt.utcluj.ro; Birleanu, Corina, E-mail: marius.pustan@omt.utcluj.ro; Dudescu, Cristian, E-mail: marius.pustan@omt.utcluj.ro [Laboratory of Micro and Nano Systems, Technical University of Cluj-Napoca, Bd. Muncii, no. 103-105, 400641 Cluj-Napoca (Romania)

    2015-02-17

    This paper presents the design and fabrication of a MEMS chevron-type thermal actuator. The device was designed for fabrication in the standard MEMS technology, where the topography of the upper layers depends on the patterns of structural and sacrificial layers underneath. The proposed actuator presents some advantages over usual thermal vertical chevron actuators by means of low operating voltages, high output force and linear movement without deformation of the shaft. The device simulations were done using COVENTOR software. The movement obtained by simulation was 12 μm, for a voltage of 0.2 V and the current intensity of 257 mA. The design optimizes the in-plane displacement by fixed anchors and beam inclination angle. Heating is provided by Joule dissipation. The material used for manufacture of chevron-based actuator was aluminum due to its thermal and mechanical properties. The release of the movable part was performed using isotropic dry etching by Reactive Ion Etching (RIE). A first inspection was achieved using Scanning Electron Microscope (SEM). In order to obtain the in-plane displacement we carried out electrical measurements. The thermal actuator can be used for a variety of optical and microassembling applications. This kind of thermal actuator could be integrated easily with other micro devices since its fabrication is compatible with the general semiconductor processes.

  13. Calculations of the nozzle coefficient of discharge of wet steam turbine stages

    International Nuclear Information System (INIS)

    Jinling, Z.; Yinian, C.

    1989-01-01

    A method is presented for calculating the coefficient of discharge of wet steam turbine nozzles. The theoretical formulation of the problem is rigorously in accordance with the theory of two-phase wet steam expansion flow through steam turbine nozzles. The computational values are plotted as sets of curves in accordance with orthogonality test principles. They agree satisfactorily both with historical empirical data and the most recent experimental data obtained in the wet steam two-phase flow laboratory of Xian Jiaotong University. (author)

  14. Thrust characteristics of a series of convergent-divergent exhaust nozzles at subsonic and supersonic flight speeds

    Science.gov (United States)

    Fradenburgh, Evan A; Gorton, Gerald C; Beke, Andrew

    1954-01-01

    An experimental investigation of a series of four convergent-divergent exhaust nozzles was conducted in the Lewis 8-by-6 foot supersonic wind tunnel at Mach numbers of 0.1, 0.6, 1.6, and 2.0 over a range of nozzle pressure ratios. The thrust characteristics of these nozzles were determined by a pressure-integration technique. From a thrust standpoint, a nozzle designed to give uniform parallel flow at the exit had no advantage over the simple geometric design with conical convergent and divergent sections. The rapid-divergent nozzles might be competitive with the more gradual-divergent nozzles since the relatively short length of these nozzles would be advantageous from a weight standpoint and might result in smaller thrust losses due to friction. The thrusts, with friction losses neglected, were predicted satisfactorily by one-dimensional theory for the nozzles with relatively gradual divergence. The thrusts of the rapid-divergent designs were several percentages below the theoretical values at the design pressure ratio or above, while at low pressure ratios there was a considerable effect of free-stream Mach number, with thrusts considerably above theoretical values at subsonic speeds and somewhat above theoretical values at supersonic speeds. This Mach numb effect appeared to be related to the variation of the model base pressure with free-stream Mach number.

  15. Thrust Augmented Nozzle for a Hybrid Rocket with a Helical Fuel Port

    Science.gov (United States)

    Marshall, Joel H.

    A thrust augmented nozzle for hybrid rocket systems is investigated. The design lever-ages 3-D additive manufacturing to embed a helical fuel port into the thrust chamber of a hybrid rocket burning gaseous oxygen and ABS plastic as propellants. The helical port significantly increases how quickly the fuel burns, resulting in a fuel-rich exhaust exiting the nozzle. When a secondary gaseous oxygen flow is injected into the nozzle downstream of the throat, all of the remaining unburned fuel in the plume spontaneously ignites. This secondary reaction produces additional high pressure gases that are captured by the nozzle and significantly increases the motor's performance. Secondary injection and combustion allows a high expansion ratio (area of the nozzle exit divided by area of the throat) to be effective at low altitudes where there would normally be significantly flow separation and possibly an embedded shock wave due. The result is a 15 percent increase in produced thrust level with no loss in engine efficiency due to secondary injection. Core flow efficiency was increased significantly. Control tests performed using cylindrical fuel ports with secondary injection, and helical fuel ports without secondary injection did not exhibit this performance increase. Clearly, both the fuel-rich plume and secondary injection are essential features allowing the hybrid thrust augmentation to occur. Techniques for better design optimization are discussed.

  16. Designs of contraction nozzle and concave back-wall for IFMIF target

    Energy Technology Data Exchange (ETDEWEB)

    Ida, Mizuho E-mail: ida@ifmif.tokai.jaeri.go.jp; Nakamura, Hideo; Nakamura, Hiroo; Takeuchi, Hiroshi

    2004-02-01

    For the liquid lithium flow target of International Fusion Materials Irradiation Facility (IFMIF), the double reducer (two-step contraction) nozzle with a high-contraction ratio of 10 which generated high-speed uniform jet flows up to 20 m/s was proposed. Multi-dimensional hydraulic analyses were carried out to verify the performance of the proposed nozzle. The analytical results showed that the double reducer nozzle would well generate high-speed uniform flow, while one-step contraction nozzle generated non-uniform flow and resulted in flow thickening at the beam footprint. For the target design, the range of the concave back-wall radius with no lithium boiling due to the centrifugal force and proper component arrangement in the irradiation test cell was determined by the thermal-hydraulic analysis of a free-surface flow. It was verified that the back-wall radius from 0.25 to 10 m was acceptable in the velocity range of 10-20 m/s.

  17. Designs of contraction nozzle and concave back-wall for IFMIF target

    International Nuclear Information System (INIS)

    Ida, Mizuho; Nakamura, Hideo; Nakamura, Hiroo; Takeuchi, Hiroshi

    2004-01-01

    For the liquid lithium flow target of International Fusion Materials Irradiation Facility (IFMIF), the double reducer (two-step contraction) nozzle with a high-contraction ratio of 10 which generated high-speed uniform jet flows up to 20 m/s was proposed. Multi-dimensional hydraulic analyses were carried out to verify the performance of the proposed nozzle. The analytical results showed that the double reducer nozzle would well generate high-speed uniform flow, while one-step contraction nozzle generated non-uniform flow and resulted in flow thickening at the beam footprint. For the target design, the range of the concave back-wall radius with no lithium boiling due to the centrifugal force and proper component arrangement in the irradiation test cell was determined by the thermal-hydraulic analysis of a free-surface flow. It was verified that the back-wall radius from 0.25 to 10 m was acceptable in the velocity range of 10-20 m/s

  18. CFD Models of a Serpentine Inlet, Fan, and Nozzle

    Science.gov (United States)

    Chima, R. V.; Arend, D. J.; Castner, R. S.; Slater, J. W.; Truax, P. P.

    2010-01-01

    Several computational fluid dynamics (CFD) codes were used to analyze the Versatile Integrated Inlet Propulsion Aerodynamics Rig (VIIPAR) located at NASA Glenn Research Center. The rig consists of a serpentine inlet, a rake assembly, inlet guide vanes, a 12-in. diameter tip-turbine driven fan stage, exit rakes or probes, and an exhaust nozzle with a translating centerbody. The analyses were done to develop computational capabilities for modeling inlet/fan interaction and to help interpret experimental data. Three-dimensional Reynolds averaged Navier-Stokes (RANS) calculations of the fan stage were used to predict the operating line of the stage, the effects of leakage from the turbine stream, and the effects of inlet guide vane (IGV) setting angle. Coupled axisymmetric calculations of a bellmouth, fan, and nozzle were used to develop techniques for coupling codes together and to investigate possible effects of the nozzle on the fan. RANS calculations of the serpentine inlet were coupled to Euler calculations of the fan to investigate the complete inlet/fan system. Computed wall static pressures along the inlet centerline agreed reasonably well with experimental data but computed total pressures at the aerodynamic interface plane (AIP) showed significant differences from the data. Inlet distortion was shown to reduce the fan corrected flow and pressure ratio, and was not completely eliminated by passage through the fan

  19. Supersonic flaw detection device for nozzle

    International Nuclear Information System (INIS)

    Hata, Moriki.

    1996-01-01

    In a supersonic flaw detection device to be attached to a body surface of a reactor pressure vessel for automatically detecting flaws of a welded portion of a horizontally connected nozzle by using supersonic waves, a running vehicle automatically running along a circumferential direction of the nozzle comprises a supersonic flaw detection means for detecting flaws of the welded portion of the nozzle by using supersonic waves, and an inclination angle sensor for detecting the inclination angle of the running vehicle relative to the central axis of the nozzle. The running distance of the vehicle running along the circumference of the nozzle, namely, the position of the running vehicle from a reference point of the nozzle can be detected accurately by dividing the distance around the nozzle by the inclination angle detected by the inclination angle sensor. Accordingly, disadvantages in the prior art, for example, that the detected values obtained by using an encoder are changed by slipping or idle running of the magnet wheels are eliminated, and accurate flaw detection can be conducted. In addition, an operation of visually adjusting the reference point for the device can be eliminated. An operator's exposure dose can be reduced. (N.H.)

  20. Inverse estimation of heat flux and temperature on nozzle throat-insert inner contour

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Tsung-Chien [Department of Power Vehicle and Systems Engineering, Chung Cheng Institute of Technology, National Defense University, Ta-Hsi, Tao-Yuan 33509 (China); Liu, Chiun-Chien [Chung Shan Institute of Science and Technology, Lung-Tan, Tao-Yuan 32526 (China)

    2008-07-01

    During the missile flight, the jet flow with high temperature comes from the heat flux of propellant burning. An enormous heat flux from the nozzle throat-insert inner contour conducted into the nozzle shell will degrade the material strength of nozzle shell and reduce the nozzle thrust efficiency. In this paper, an on-line inverse method based on the input estimation method combined with the finite-element scheme is proposed to inversely estimate the unknown heat flux on the nozzle throat-insert inner contour and the inner wall temperature by applying the temperature measurements of the nozzle throat-insert. The finite-element scheme can easily define the irregularly shaped boundary. The superior capability of the proposed method is demonstrated in two major time-varying estimation cases. The computational results show that the proposed method has good estimation performance and highly facilitates the practical implementation. An effective analytical method can be offered to increase the operation reliability and thermal-resistance layer design in the solid rocket motor. (author)

  1. Applicability of fan spray nozzles to stripping insoluble gases from viscous liquids

    International Nuclear Information System (INIS)

    Tseng, H.H.; Johnson, E.F.

    1983-08-01

    Fan spray nozzle stripping appears to be a practical technique for separating dilute volatile solutes from nonvolatile solvents. In particular this technique can be used to strip molecular tritium and tritium fluoride at extremely small concentration (in the parts per million range) from molten salts used as blanket materials in a fusion reactor. Under adjusted operating conditions of the fan spray as it leaves the nozzle, a high percentage of the theoretically maximum achievable stripping would take place from the expanding sheet of the fan spray as it leaves the nozzle and before it breaks up. Although the only available experimental data are for aqueous solutions, a new theoretical analysis of the fan spray sheet demonstrates the applicability of this technique to nonaqueous liquids. The equation derived from this analysis relates the theoretically achievable mass transfer efficiency to the properties of the liquid flowing through the fan spray nozzle and to the operating conditions of the nozzle. Any fluid with viscosity higher than or equal to that of water would be expected to follow this equation as long as a fan-shaped sheet is formed under the operating conditions of the nozzle

  2. Combustion Dynamics in Multi-Nozzle Combustors Operating on High-Hydrogen Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Santavicca, Dom; Lieuwen, Tim

    2013-09-30

    Actual gas turbine combustors for power generation applications employ multi-nozzle combustor configurations. Researchers at Penn State and Georgia Tech have extended previous work on the flame response in single-nozzle combustors to the more realistic case of multi-nozzle combustors. Research at Georgia Tech has shown that asymmetry of both the flow field and the acoustic forcing can have a significant effect on flame response and that such behavior is important in multi-flame configurations. As a result, the structure of the flame and its response to forcing is three-dimensional. Research at Penn State has led to the development of a three-dimensional chemiluminescence flame imaging technique that can be used to characterize the unforced (steady) and forced (unsteady) flame structure of multi-nozzle combustors. Important aspects of the flame response in multi-nozzle combustors which are being studied include flame-flame and flame-wall interactions. Research at Penn State using the recently developed three-dimensional flame imaging technique has shown that spatial variations in local flame confinement must be accounted for to accurately predict global flame response in a multi-nozzle can combustor.

  3. Jet Noise Scaling in Dual Stream Nozzles

    Science.gov (United States)

    Khavaran, Abbas; Bridges, James

    2010-01-01

    Power spectral laws in dual stream jets are studied by considering such flows a superposition of appropriate single-stream coaxial jets. Noise generation in each mixing region is modeled using spectral power laws developed earlier for single stream jets as a function of jet temperature and observer angle. Similarity arguments indicate that jet noise in dual stream nozzles may be considered as a composite of four single stream jets representing primary/secondary, secondary/ambient, transition, and fully mixed zones. Frequency filter are designed to highlight spectral contribution from each jet. Predictions are provided at an area ratio of 2.0--bypass ratio from 0.80 to 3.40, and are compared with measurements within a wide range of velocity and temperature ratios. These models suggest that the low frequency noise in unheated jets is dominated by the fully mixed region at all velocity ratios, while the high frequency noise is dominated by the secondary when the velocity ratio is larger than 0.80. Transition and fully mixed jets equally dominate the low frequency noise in heated jets. At velocity ratios less than 0.50, the high frequency noise from primary/bypass becomes a significant contributing factor similar to that in the secondary/ambient jet.

  4. Determine spray droplets on water sensitive paper (WSP) for low pressure deflector nozzle using image J

    Science.gov (United States)

    Sies, M. F.; Madzlan, N. F.; Asmuin, N.; Sadikin, A.; Zakaria, H.

    2017-09-01

    In this study, determine of spray droplets size (SMD) using water sensitive paper (WSP) at low fluid pressure with deflector nozzle or tangential flow nozzle model Delavan AL75 and New Design Nozzle with two different type of swirl (ND2.5 A1.0 & ND2.5 B1.0). These three deflected flat sprays have used at different liquid mixing ratio. These liquid mixture ratios are pure water, 10% of lime juice + 90% of water (L10W90) and 30% of lime juice + 70% of water (L30W70). WSP is used to collect the spray droplets from nozzles. The operational liquid pressure of each nozzle is 3 bar, while air operational pressures are 3 bar and 6 bar. Then, the WSP were scanned using scanner then it was analyzed using ImageJ software. ImageJ can be used for determining the diameter of droplets size on the WSP. As the results from an experiment, the AL75 nozzle recorded the lowest Sauter mean diameter which is 193.69μm at 6 bar of pressurized air while ND2.5 A1.0 recorded the highest Sauter mean diameter which is 353.61µm at 3 bar of pressurized air. Summary from the experiment shows that the higher of droplet size is because of the lower air pressure (3 Bar). Then, increasing of liquid viscosity also increase the SMD. The orifice diameter for New Design nozzle (ND-2.5) is smaller than AL75, which are 2.5mm and 2.8mm respectively. The different nozzle design also gives effect the SMD. WSP is an alternative method to determine SMD for spray droplets with the low cost if compared to Phase Doppler Anemometry (PDA).

  5. CFD Based Erosion Modelling of Abrasive Waterjet Nozzle using Discrete Phase Method

    International Nuclear Information System (INIS)

    Kamarudin, Naqib Hakim; Prasada Rao, A K; Azhari, Azmir

    2016-01-01

    In Abrasive Waterjet (AWJ) machining, the nozzle is the most critical component that influences the performance, precision and economy. Exposure to a high speed jet and abrasives makes it susceptible to wear erosion which requires for frequent replacement. The present works attempts to simulate the erosion of the nozzle wall using computational fluid dynamics. The erosion rate of the nozzle was simulated under different operating conditions. The simulation was carried out in several steps which is flow modelling, particle tracking and erosion rate calculation. Discrete Phase Method (DPM) and K-ε turbulence model was used for the simulation. Result shows that different operating conditions affect the erosion rate as well as the flow interaction of water, air and abrasives. The simulation results correlates well with past work. (paper)

  6. Numerical modelling of the jet nozzle enrichment process

    International Nuclear Information System (INIS)

    Vercelli, P.

    1983-01-01

    A numerical model was developed for the simulation of the isotopic enrichment produced by the jet nozzle process. The flow was considered stationary and under ideal gas conditions. The model calculates, for any position of the skimmer piece: (a) values of radial mass concentration profiles for each isotopic species and (b) values of elementary separation effect (Σ sub(A)) and uranium cut (theta). The comparison of the numerical results obtained with the experimental values given in the literature proves the validity of the present work as an initial step in the modelling of the process. (Author) [pt

  7. Integrated Composite Rocket Nozzle Extension, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop and demonstrate an Integrated Composite Rocket Nozzle Extension (ICRNE) for use in rocket thrust chambers. The ICRNE will utilize an...

  8. Aerospike Nozzle for Rotating Detonation Engine Application

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal presents a graduate MS research thesis on improving the efficiency of rotating detonation engines by using aerospike nozzle technologies. A rotating...

  9. Experimental observations of a complex, supersonic nozzle concept

    Science.gov (United States)

    Magstadt, Andrew; Berry, Matthew; Glauser, Mark; Ruscher, Christopher; Gogineni, Sivaram; Kiel, Barry; Skytop Turbulence Labs, Syracuse University Team; Spectral Energies, LLC. Team; Air Force Research Laboratory Team

    2015-11-01

    A complex nozzle concept, which fuses multiple canonical flows together, has been experimentally investigated via pressure, schlieren and PIV in the anechoic chamber at Syracuse University. Motivated by future engine designs of high-performance aircraft, the rectangular, supersonic jet under investigation has a single plane of symmetry, an additional shear layer (referred to as a wall jet) and an aft deck representative of airframe integration. Operating near a Reynolds number of 3 ×106 , the nozzle architecture creates an intricate flow field comprised of high turbulence levels, shocks, shear & boundary layers, and powerful corner vortices. Current data suggest that the wall jet, which is an order of magnitude less energetic than the core, has significant control authority over the acoustic power through some non-linear process. As sound is a direct product of turbulence, experimental and analytical efforts further explore this interesting phenomenon associated with the turbulent flow. The authors acknowledge the funding source, a SBIR Phase II project with Spectral Energies, LLC. and AFRL turbine engine branch under the direction of Dr. Barry Kiel.

  10. Design and Analysis of Fused Deposition Modeling 3D Printer Nozzle for Color Mixing

    Directory of Open Access Journals (Sweden)

    Shanling Han

    2017-01-01

    Full Text Available Fused deposition modeling (FDM has been one of the most widely used rapid prototyping (RP technologies leading to the increase in market attention. Obviously it is desirable to print 3D objects; however, existing FDM printers are restricted to printing only monochrome objects because of the entry-level nozzle structure, and literature on the topic is also sparse. In this paper, the CAD model of the nozzle is established first by UG (Unigraphics NX software to show the structure of fused deposition modeling 3D printer nozzle for color mixing. Second, the flow channel model of the nozzle is extracted and simplified. Then, the CAD and finite element model are established by UG and ICEM CFD software, respectively, to prepare for the simulation. The flow field is simulated by Fluent software. The nozzle’s suitable temperature at different extrusion speeds is obtained, and the reason for the blockage at the intersection of the heating block is revealed. Finally, test verification of the nozzle is performed, which can produce mixed-color artifacts stably.

  11. On the influence of the nozzle length on the arc properties in a cutting torch

    International Nuclear Information System (INIS)

    Prevosto, L; Risso, M; Infante, D; Kelly, H

    2009-01-01

    In this work, an experimental study on the influence of the nozzle geometry on the physical properties of a cutting arc is reported. Ion current signals collected by an electrostatic probe sweeping across a 30 A oxygen cutting arc at 3.5 mm from the nozzle exit were registered for different nozzle lengths. The temperature and density radial profiles of the arc plasma were found in each case by an inversion procedure of these signals. A comparison between the obtained results shows that the shorter nozzle (R N = 0.50 mm, L N = 4.5 mm operated at 0.7 MPa and 35 Nl/min) produces a thinner and hotter arc than the larger nozzle (R N = 0.50 mm, L N = 9.0 mm operated at 1.1 MPa and 20 Nl/min). This behavior is attributed to the marked difference of gas flow rate due to the clogging effect. A smaller gas mass flow reduces the convective cooling at the arc border and decreases the power dissipation of the arc column, resulting in small axis temperatures.

  12. On the influence of the nozzle length on the arc properties in a cutting torch

    Energy Technology Data Exchange (ETDEWEB)

    Prevosto, L; Risso, M; Infante, D [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Universidad Tecnologica Nacional, Regional Venado Tuerto, Las Heras 644, Venado Tuerto (2600), Santa Fe (Argentina); Kelly, H, E-mail: prevosto@waycom.com.a [Instituto de FIsica del Plasma (CONICET), Departamento de Fisica, Facultad de Ciencias Exactas y Naturales (UBA) Ciudad Universitaria Pab. I, 1428 Buenos Aires (Argentina)

    2009-05-01

    In this work, an experimental study on the influence of the nozzle geometry on the physical properties of a cutting arc is reported. Ion current signals collected by an electrostatic probe sweeping across a 30 A oxygen cutting arc at 3.5 mm from the nozzle exit were registered for different nozzle lengths. The temperature and density radial profiles of the arc plasma were found in each case by an inversion procedure of these signals. A comparison between the obtained results shows that the shorter nozzle (R{sub N} = 0.50 mm, L{sub N} = 4.5 mm operated at 0.7 MPa and 35 Nl/min) produces a thinner and hotter arc than the larger nozzle (R{sub N} = 0.50 mm, L{sub N} = 9.0 mm operated at 1.1 MPa and 20 Nl/min). This behavior is attributed to the marked difference of gas flow rate due to the clogging effect. A smaller gas mass flow reduces the convective cooling at the arc border and decreases the power dissipation of the arc column, resulting in small axis temperatures.

  13. Launch Environment Water Flow Simulations Using Smoothed Particle Hydrodynamics

    Science.gov (United States)

    Vu, Bruce T.; Berg, Jared J.; Harris, Michael F.; Crespo, Alejandro C.

    2015-01-01

    This paper describes the use of Smoothed Particle Hydrodynamics (SPH) to simulate the water flow from the rainbird nozzle system used in the sound suppression system during pad abort and nominal launch. The simulations help determine if water from rainbird nozzles will impinge on the rocket nozzles and other sensitive ground support elements.

  14. Experimental analysis on the influence of nozzle geometry over the dispersion of liquid n-dodecane sprays

    Directory of Open Access Journals (Sweden)

    Raul ePayri

    2015-10-01

    Full Text Available Understanding and controlling mixing and combustion processes is fundamental in order to face the challenges set by the ever more demanding pollutant regulations and fuel consumption standards of direct injection diesel engines. The fundamentals of these processes haven been long studied by the diesel spray community from both experimental and numerical perspectives. However, certain topics such as the influence of nozzle geometry over the spray atomization, mixing and combustion process are still not completely well understood and predicted by numerical models. The present study seeks to contribute to the current understanding of this subject, by performing state-of-the-art optical diagnostics to liquid sprays injected through two singe-hole nozzles of different conicity. The experiments were carried out in a nitrogen-filled constant-pressure-flow facility. Back pressures were set to produce the desired engine-like density conditions in the chamber, at room temperature. The experimental setup consists in a diffused back illumination setup with a fast pulsed LED light source and a high-speed camera. The diagnostics focused on detecting the liquid spray contour and evaluating the influence of nozzle geometry over the time-resolved and quasi-steady response of the spray dispersion, at similar injection conditions. Results show a clear influence of nozzle geometry on spray contour fluctuations, where the cylindrical nozzle seems to produce larger dispersion in both time-resolved fluctuations and quasi-steady values, when compared to the conical nozzle. This evidences that the turbulence and radial velocity profiles originated at the cylindrical nozzle geometry are able to affect not only the microscopic scales inside the nozzle, but also macroscopic scales such as the steady spray. Observations from this study indicate that the effects of the flow characteristics within the nozzle are carried on to the first millimeters of the spray, in which the

  15. Minimally Invasive and Open Distal Chevron Osteotomy for Mild to Moderate Hallux Valgus.

    Science.gov (United States)

    Brogan, Kit; Lindisfarne, Edward; Akehurst, Harold; Farook, Usama; Shrier, Will; Palmer, Simon

    2016-11-01

    Minimally invasive surgical (MIS) techniques are increasingly being used in foot and ankle surgery but it is important that they are adopted only once they have been shown to be equivalent or superior to open techniques. We believe that the main advantages of MIS are found in the early postoperative period, but in order to adopt it as a technique longer-term studies are required. The aim of this study was to compare the 2-year outcomes of a third-generation MIS distal chevron osteotomy with a comparable traditional open distal chevron osteotomy for mild-moderate hallux valgus. Our null hypothesis was that the 2 techniques would yield equivalent clinical and radiographic results at 2 years. This was a retrospective cohort study. Eighty-one consecutive feet (49 MIS and 32 open distal chevron osteotomies) were followed up for a minimum 24 months (range 24-58). All patients were clinically assessed using the Manchester-Oxford Foot Questionnaire. Radiographic measures included hallux valgus angle, the intermetatarsal angle, hallux interphalangeal angle, metatarsal phalangeal joint angle, distal metatarsal articular angle, tibial sesamoid position, shape of the first metatarsal head, and plantar offset. Statistical analysis was done using Student t test or Wilcoxon rank-sum test for continuous data and Pearson chi-square test for categorical data. Clinical and radiologic postoperative scores in all domains were substantially improved in both groups (P .05). There were no significant differences in complications between the 2 groups ( > .5). The midterm results of this third-generation technique show that it was a safe procedure with good clinical outcomes and comparable to traditional open techniques for symptomatic mild-moderate hallux valgus. Level III, retrospective comparative study. © The Author(s) 2016.

  16. Single nozzle spray drift measurements of drift reducing nozzles at two forward speeds

    NARCIS (Netherlands)

    Stallinga, H.; Zande, van de J.C.; Michielsen, J.G.P.; Velde, van P.

    2016-01-01

    In 2011‒2012 single nozzle field experiments were carried out to determine the effect of different flat fan spray nozzles of the spray drift reduction classes 50, 75, 90 and 95% on spray drift at two different forward speeds (7.2 km h-1 and 14.4 km h-1). Experiments were performed with a single

  17. Preliminary Two-Phase Terry Turbine Nozzle Models for RCIC Off-Design Operation Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Haihua [Idaho National Lab. (INL), Idaho Falls, ID (United States); O' Brien, James [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-06-12

    This report presents the effort to extend the single-phase analytical Terry turbine model to cover two-phase off-design conditions. The work includes: (1) adding well-established two-phase choking models – the Isentropic Homogenous Equilibrium Model (IHEM) and Moody’s model, and (2) theoretical development and implementation of a two-phase nozzle expansion model. The two choking models provide bounding cases for the two-phase choking mass flow rate. The new two-phase Terry turbine model uses the choking models to calculate the mass flow rate, the critical pressure at the nozzle throat, and steam quality. In the divergent stage, we only consider the vapor phase with a similar model for the single-phase case by assuming that the liquid phase would slip along the wall with a much slower speed and will not contribute the impulse on the rotor. We also modify the stagnation conditions according to two-phase choking conditions at the throat and the cross-section areas for steam flow at the nozzle throat and at the nozzle exit. The new two-phase Terry turbine model was benchmarked with the same steam nozzle test as for the single-phase model. Better agreement with the experimental data is observed than from the single-phase model. We also repeated the Terry turbine nozzle benchmark work against the Sandia CFD simulation results with the two-phase model for the pure steam inlet nozzle case. The RCIC start-up tests were simulated and compared with the single-phase model. Similar results are obtained. Finally, we designed a new RCIC system test case to simulate the self-regulated Terry turbine behavior observed in Fukushima accidents. In this test, a period inlet condition for the steam quality varying from 1 to 0 is applied. For the high quality inlet period, the RCIC system behaves just like the normal operation condition with a high pump injection flow rate and a nominal steam release rate through the turbine, with the net addition of water to the primary system; for

  18. Investigation of Acoustic Emission during Fracture Toughness Testing of Chevron-Notched Specimens.

    Science.gov (United States)

    1984-03-01

    chevron-notched specimlens was employed to investigate crack growth in four steels )rel)ared by electroslag-remelt casting. 15-5PH, AISI 4140 , D6AC, and...this investigation: 15-SPH, AISI 4140 , D6AC and AISI 440C. The composition of each steel is given in Table 1. Castings were prepared by electro- slag...well defined, it appears that the AISI 4140 (Figure 2b) and the D6AC (Figure 2c) failed primarily by cleavage also. The fracture illustrated in Figure

  19. Outcomes in chevron osteotomy for Hallux Valgus in a large cohort.

    Science.gov (United States)

    van Groningen, Bart; van der Steen, M C Marieke; Reijman, Max; Bos, Janneke; Hendriks, Johannes G E

    2016-12-01

    Clinical and radiological related outcomes have been reported for Chevron osteotomy as correction for mild to moderate hallux valgus, but only for relatively small patient series. Moreover, evaluation of the patient's point of view has mostly been conducted by means of more physician-based outcome measures. The goal of this study was to evaluate the effect of the Chevron osteotomy for hallux valgus on patients' daily lives using the Foot and Ankle Outcome Score (FAOS) as a validated and a hallux valgus specific patient reported outcome measure (PROM). Secondary outcome measures were radiological correction, complication rate, and re-operations. All 438 Chevron procedures (336 patients), at two surgical hospital sites in the period between January 2010 and October 2014, were retrospectively evaluated with a follow-up of at least 6 months. Patients were invited to fill in a cross-sectional online FAOS. For the FAOS, a total response of 60% was achieved. The FAOS ranged between 71 and 88 with a follow-up of on average 36 months. Patients with an undercorrection of their hallux valgus (11.6% of the procedures) scored significantly lower on three subscales of the FAOS (range between 61 and 77 versus 72-84). Patients who had a reoperation (12.6% of the procedures) also scored significantly lower on four subscales: 58-100 versus 73-89. Postoperative radiological measurements improved significantly with a mean difference of 6.1 (5.9; 6.4) degrees for the intermetatarsal angle and 13.7 (13.0; 14.5) degrees for the hallux valgus angle. In this large study cohort, Chevron osteotomy for hallux valgus offers good PROM scores on FAOS. These scores were significantly lower in patients with radiological undercorrection or with a reoperation. Results of the FAOS appear to modulate with physician based outcomes and therapeutic incidents. Improvement of outcome may therefore well be possible by increased attention on these surgical details. Copyright © 2016 Elsevier Ltd. All rights

  20. Modified Chevron osteotomy for hallux valgus deformity in female athletes. A 2-year follow-up study.

    Science.gov (United States)

    Giotis, Dimitrios; Paschos, Nikolaos K; Zampeli, Franceska; Giannoulis, Dionisios; Gantsos, Apostolos; Mantellos, George

    2016-09-01

    Hallux valgus is an increasingly common deformity in young female athletes that constricts their daily athletic activities and influences foot cosmesis. The aim of this study was to evaluate the outcome of modified Chevron osteotomy for hallux valgus deformity in this specific population. Forty-two cases of modified Chevron osteotomies were carried out in 33 patients with mild to moderate hallux valgus deformity. Each participant was evaluated for AOFAS score, pain, range of motion, cosmetic and radiological outcome. Mean AOFAS score improved to 96.3 (phallux valgus deformity in young female athletes, with excellent clinical outcome. Copyright © 2015 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

  1. Methods and systems to thermally protect fuel nozzles in combustion systems

    Science.gov (United States)

    Helmick, David Andrew; Johnson, Thomas Edward; York, William David; Lacy, Benjamin Paul

    2013-12-17

    A method of assembling a gas turbine engine is provided. The method includes coupling a combustor in flow communication with a compressor such that the combustor receives at least some of the air discharged by the compressor. A fuel nozzle assembly is coupled to the combustor and includes at least one fuel nozzle that includes a plurality of interior surfaces, wherein a thermal barrier coating is applied across at least one of the plurality of interior surfaces to facilitate shielding the interior surfaces from combustion gases.

  2. Cyclic elastic analysis of a PWR nozzle subjected to a repeated thermal shock

    International Nuclear Information System (INIS)

    Locci, J.M.; Prost, J.P.

    1979-01-01

    In the primary piping system of a PWR nuclear power plant, some nozzles are subjected to strong thermal shocks due to sudden thermal variations in the internal water flow. The thermal gradients are sufficiently high to induce general elastic plastic behaviour. The design of these nozzles using the simplified elastic plastic analysis given in the ASME III Code NB-3200 generally leads to a very high usage factor. The aim of this work is to show by giving an example that a complete cyclic elastic plastic analysis makes it possible to considerably reduce the usage factor. (orig.)

  3. Structural strengthening of rocket nozzle extension by means of laser metal deposition

    Science.gov (United States)

    Honoré, M.; Brox, L.; Hallberg, M.

    2012-03-01

    Commercial space operations strive to maximize the payload per launch in order to minimize the costs of each kg launched into orbit; this yields demand for ever larger launchers with larger, more powerful rocket engines. Volvo Aero Corporation in collaboration with Snecma and Astrium has designed and tested a new, upgraded Nozzle extension for the Vulcain 2 engine configuration, denoted Vulcain 2+ NE Demonstrator The manufacturing process for the welding of the sandwich wall and the stiffening structure is developed in close cooperation with FORCE Technology. The upgrade is intended to be available for future development programs for the European Space Agency's (ESA) highly successful commercial launch vehicle, the ARIANE 5. The Vulcain 2+ Nozzle Extension Demonstrator [1] features a novel, thin-sheet laser-welded configuration, with laser metal deposition built-up 3D-features for the mounting of stiffening structure, flanges and for structural strengthening, in order to cope with the extreme load- and thermal conditions, to which the rocket nozzle extension is exposed during launch of the 750 ton ARIANE 5 launcher. Several millimeters of material thickness has been deposited by laser metal deposition without disturbing the intricate flow geometry of the nozzle cooling channels. The laser metal deposition process has been applied on a full-scale rocket nozzle demonstrator, and in excess of 15 kilometers of filler wire has been successfully applied to the rocket nozzle. The laser metal deposition has proven successful in two full-throttle, full-scale tests, firing the rocket engine and nozzle in the ESA test facility P5 by DLR in Lampoldshausen, Germany.

  4. Static and wind tunnel near-field/far-field jet noise measurements from model scale single-flow base line and suppressor nozzles. Summary report. [conducted in the Boeing large anechoic test chamber and the NASA-Ames 40by 80-foot wind tunnel

    Science.gov (United States)

    Jaeck, C. L.

    1977-01-01

    A test program was conducted in the Boeing large anechoic test chamber and the NASA-Ames 40- by 80-foot wind tunnel to study the near- and far-field jet noise characteristics of six baseline and suppressor nozzles. Static and wind-on noise source locations were determined. A technique for extrapolating near field jet noise measurements into the far field was established. It was determined if flight effects measured in the near field are the same as those in the far field. The flight effects on the jet noise levels of the baseline and suppressor nozzles were determined. Test models included a 15.24-cm round convergent nozzle, an annular nozzle with and without ejector, a 20-lobe nozzle with and without ejector, and a 57-tube nozzle with lined ejector. The static free-field test in the anechoic chamber covered nozzle pressure ratios from 1.44 to 2.25 and jet velocities from 412 to 594 m/s at a total temperature of 844 K. The wind tunnel flight effects test repeated these nozzle test conditions with ambient velocities of 0 to 92 m/s.

  5. Acoustic Investigation of Jet Mixing Noise in Dual Stream Nozzles

    Science.gov (United States)

    Khavaran, Abbas; Dahl, Milo D.

    2012-01-01

    In an earlier study, a prediction model for jet noise in dual stream jets was proposed that is founded on velocity scaling laws in single stream jets and similarity features of the mean velocity and turbulent kinetic energy in dual stream flows. The model forms a composite spectrum from four component single-stream jets each believed to represent noise-generation from a distinct region in the actual flow. While the methodology worked effectively at conditions considered earlier, recent examination of acoustic data at some unconventional conditions indicate that further improvements are necessary in order to expand the range of applicability of the model. The present work demonstrates how these predictions compare with experimental data gathered by NASA and industry for the purpose of examining the aerodynamic and acoustic performance of such nozzles for a wide range of core and fan stream conditions. Of particular interest are jets with inverted velocity and temperature profiles and the appearance of a second spectral peak at small aft angles to the jet under such conditions. It is shown that a four-component spectrum succeeds in modeling the second peak when the aft angle refraction effects are properly incorporated into the model. A tradeoff of noise emission takes place between two turbulent regions identified as transition and fully mixed regions as the fan stream velocity exceeds that of the core stream. The effect of nozzle discharge coefficients will also be discussed.

  6. Understanding of the Interaction between Clearance Leakage Flow and Main Passage Flow in a VGT Turbine

    Directory of Open Access Journals (Sweden)

    Ben Zhao

    2015-02-01

    Full Text Available The clearance flow between the nozzle and endwall in a variable geometry turbine (VGT has been numerically investigated to understand the clearance effect on the VGT performance and internal flow. It was found that the flow rate through turbine increases but the turbine efficiency decreases with height of clearance. Detailed flow field analyses indicated that most of the efficiency loss resulting from the leakage flow occurs at the upstream of the rotor area, that is, in the nozzle endwall clearance and between the nozzle vanes. There are two main mechanisms associated with this efficiency loss. One is due to the formation of the local vortex flow structure between the clearance flow and the main flow. The other is due to the impact of the clearance flow on the main flow after the nozzle throat. This impact reduces the span of shockwave with increased shockwave magnitude by changing the trajectory of the main flow.

  7. 燃气喷射推力矢量喷管气固两相流数值模拟%Numerical simulation of gas-particle flow in hot gas injection thrust vector nozzle

    Institute of Scientific and Technical Information of China (English)

    刘辉; 邢玉明

    2013-01-01

    利用Euler-Lagrangian方法模拟了固体火箭发动机燃气喷射推力矢量喷管气固两相内流场,研究了固体颗粒对喷管推力矢量性能的影响,气相采用Roe格式和MUSCL (monotone upstream-centred schemes for conservation laws)插值进行空间2阶迎风离散,时间推进采用隐式时间格式;固体颗粒相采用随机轨道模型计算颗粒轨迹,并与气相进行双向耦合.结果表明:固体颗粒的存在使弓形激波强度增强,但降低了推力矢量角和推力系数;颗粒质量分数相同时,粒径越大,推力矢量角和推力系数越大;颗粒直径相同时,颗粒质量分数越大,推力矢量角和推力系数越小.%The gas-particle inner flowfield of gas injection thrust vector nozzle in solid rocket engine was simulated using Euler-Lagrangian method, and the effect of solid particle on thrust vector performance was studied. The Roe scheme and monotone upstream-centred schemes for conservation laws (MUSCL) method were used for secondary-order accuracy spatial discretization for gas phase, and the implicit scheme was employed for time marching. The stochastic trajectory model and two-way coupled with gas phase were employed for particle phase. The results indicate that the strength of bow shock is increased due to solid particles, but the thrust vector angle and thrust coefficient are decreased; thrust vector angle and thrust coefficient increase with the particle diameter increasing under the same mass fraction of particle condition; thrust vector angle and thrust coefficient decrease with the mass fraction of particle increasing under the same particle diameter condition.

  8. Computational Investigation of Swirling Supersonic Jets Generated Through a Nozzle-Twisted Lance

    Science.gov (United States)

    Li, Mingming; Li, Qiang; Zou, Zongshu; An, Xizhong

    2017-02-01

    The dynamic characteristics of supersonic swirling jets generated through a nozzle-twisted lance are numerically studied. The essential features of the swirling jets are identified by defining a deviation angle. The effects of nozzle twist angle (NTA) on swirling flow intensity, coalescence characteristics, and dynamic parameter distributions of the jets are discussed. The rotational flow characteristics are revealed. The results show that the jets from the nozzle-twisted lance are imparted to a circumferential rotating movement around the lance axis, and such swirling flow is enhanced by increasing NTA. The enhanced swirling flow causes weaker coalescence of the jets, faster attenuations of the axial velocity, and higher heat transfer rate between the jets and surroundings. The supersonic core length, however, is found to be less sensitive to the swirling flow intensity. The radial spreading of the jets, changing non-monotonically with NTA, arrives at its maximum at 5 deg of NTA. Furthermore, the swirling flow induces a considerable tangential velocity component, and as a result, a holistic and effective horizontal swirling flow field develops. The y-vorticity distribution range and the corresponding magnitude turn larger with increasing NTA, which promote the vortex motion of the local fluid element and thus intensify the local mixing.

  9. Robotic cleaning of radwaste tank nozzles

    International Nuclear Information System (INIS)

    Boughman, G.; Jones, S.L.

    1992-01-01

    The Susquehanna radwaste processing system includes two reactor water cleanup phase separator tanks and one waste sludge phase separator tank. A system of educator nozzles and associated piping is used to provide mixing in the tanks. The mixture pumped through the nozzles is a dense resin-and-water slurry, and the nozzles tend to plug up during processing. The previous method for clearing the nozzles had been for a worker to enter the tanks and manually insert a hydrolaser into each nozzle, one at a time. The significant radiation exposure and concern for worker safety in the tank led the utility to investigate alternate means for completing this task. The typical tank configuration is shown in a figure. The initial approach investigated was to insert a manipulator arm in the tank. This arm would be installed by workers and then teleoperated from a remote control station. This approach was abandoned because of several considerations including educator location and orientation, excessive installation time, and cost. The next approach was to use a mobile platform that would operate on the tank floor. This approach was selected as being the most feasible solution. After a competitive selection process, REMOTEC was selected to provide the mobile platform. Their proposal was based on the commercial ANDROS Mark 5 platform

  10. Aeroelastic Modeling of a Nozzle Startup Transient

    Science.gov (United States)

    Wang, Ten-See; Zhao, Xiang; Zhang, Sijun; Chen, Yen-Sen

    2014-01-01

    Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in development during test. While three-dimensional, transient, turbulent, chemically reacting computational fluid dynamics methodology has been demonstrated to capture major side load physics with rigid nozzles, hot-fire tests often show nozzle structure deformation during major side load events, leading to structural damages if structural strengthening measures were not taken. The modeling picture is incomplete without the capability to address the two-way responses between the structure and fluid. The objective of this study is to develop a tightly coupled aeroelastic modeling algorithm by implementing the necessary structural dynamics component into an anchored computational fluid dynamics methodology. The computational fluid dynamics component is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, while the computational structural dynamics component is developed under the framework of modal analysis. Transient aeroelastic nozzle startup analyses at sea level were performed, and the computed transient nozzle fluid-structure interaction physics presented,

  11. Ultra low injection angle fuel holes in a combustor fuel nozzle

    Science.gov (United States)

    York, William David

    2012-10-23

    A fuel nozzle for a combustor includes a mixing passage through which fluid is directed toward a combustion area and a plurality of swirler vanes disposed in the mixing passage. Each swirler vane of the plurality of swirler vanes includes at least one fuel hole through which fuel enters the mixing passage in an injection direction substantially parallel to an outer surface of the plurality of swirler vanes thereby decreasing a flameholding tendency of the fuel nozzle. A method of operating a fuel nozzle for a combustor includes flowing a fluid through a mixing passage past a plurality of swirler vanes and injecting a fuel into the mixing passage in an injection direction substantially parallel to an outer surface of the plurality of swirler vanes.

  12. Development of technique to apply induction heating stress improvement to recirculation inlet nozzle

    International Nuclear Information System (INIS)

    Chiba, Kunihiko; Nihei, Kenichi; Ootaka, Minoru

    2009-01-01

    Stress corrosion cracking (SCC) have been found in the primary loop recirculation (PLR) systems of boiling water reactors (BWR). Residual stress in welding heat-affected zone is one of the factors of SCC, and the residual stress improvement is one of the most effective methods to prevent SCC. Induction heating stress improvement (IHSI) is one of the techniques to improve reduce residual stress. However, it is difficult to apply IHSI to the place such as the recirculation inlet nozzle where the flow stagnates. In this present study, the technique to apply IHSI to the recirculation inlet nozzle was developed using water jet which blowed into the crevice between the nozzle safe end and the thermal sleeve. (author)

  13. Fluid and structural dynamic design considerations of the HYLIFE nozzle plate

    International Nuclear Information System (INIS)

    Pitts, J.H.; Ojalvo, I.U.

    1981-02-01

    The basic concept of the High Yield Lithium Injection Fusion Energy (HYLIFE) reaction chamber involves a falling liquid-metal (lithium) jet array that absorbs 90% of the energy released from inertial confinement fusion reactions. The key element of the chamber that produces the jet array is the nozzle plate. This paper describes the design and analysis of a nozzle plate which can withstand the structural loads and permit the fluid jet array to be reestablished for a 1-Hz fusion reaction frequency. The shape of the nozzle plate and jet array is dictated by considerations of fluid dynamics and neutron-shielding. A vertical jet array, rather than a single annulus, is used because this design enhances fluid momentum interchange and dissipation of the kinetic energy that occurs when the jets disassemble. Less net outward-directed momentum results than with a single liquid annular flow configuration, thus producing lower stresses in the structural components

  14. Aerodynamic forces estimation on jet vanes exposed to supersonic exhaust of a CD Nozzle

    International Nuclear Information System (INIS)

    Bukhari, S.B.H.; Jehan, I.; Zahir, S.; Khan, M.A.

    2003-01-01

    A comprehensive study has been made for the estimation of aerodynamic forces on the jet Vane placed in the supersonic exhaust of a Convergent Divergent, CD-Nozzle. Such a system is used to provide the control forces that consist of four orthogonal vanes mounted in the supersonic exhaust of the CD-Nozzles. The flow field parameters for a CD Nozzle were analyzed and validated earlier. In this paper the published experimental and CFD results from RAMPANT Code from Fluent Inc. were used to estimate the axial and normal forces by using PAK-3D, a Computational Fluid Dynamics (CFD) software based on Navier-Stokes Equations solver. Results got verified quantitatively with a maximum error of 8% between PAK-3D and experiment, while 4% between PAK-3D and a CFD code, RAMPANT for the axial force. (author)

  15. Monitoring Approach to Evaluate the Performances of a New Deposition Nozzle Solution for DED Systems

    Directory of Open Access Journals (Sweden)

    Federico Mazzucato

    2017-05-01

    Full Text Available Abstract: In order to improve the process efficiency of a direct energy deposition (DED system, closed loop control systems can be considered for monitoring the deposition and melting processes and adjusting the process parameters in real-time. In this paper, the monitoring of a new deposition nozzle solution for DED systems is approached through a simulation-experimental comparison. The shape of the powder flow at the exit of the nozzle outlet and the spread of the powder particles on the deposition plane are analyzed through 2D images of the powder flow obtained by monitoring the powder depositions with a high-speed camera. These experimental results are then compared with data obtained through a Computational Fluid Dynamics model. Preliminary tests are carried out by varying powder, carrier, and shielding mass flow, demonstrating that the last parameter has a significant influence on the powder distribution and powder flow geometry.

  16. Magnetic-Laval-Nozzle Effect on a Magneto-Plasma-Dynamic Arcjet

    International Nuclear Information System (INIS)

    Inutake, Masaaki; Miyazaki, Hiroyuki; Yoshino, Kyohei; Tobari, Hiroyuki; Hattori, Kunihiko; Ando, Akira

    2003-01-01

    A magneto-plasma-dynamic arcjet (MPDA) is one of the promising candidates for a manned interplanetary space thruster with a higher specific impulse and larger thrust. An MPDA with an externally-applied magnetic nozzle is investigated to improve the thrust efficiency. From spectroscopic measurements of the MPDA plasma, it is found that with the increase in the discharge current not only the flow velocity but also the ion temperature increase near the muzzle of the MPDA with a uniform axial magnetic field and so the ion acoustic Mach number is limited to a value less than unity. By installing a Laval-type magnetic nozzle near the muzzle of the MPDA, the subsonic flow is successfully accelerated to a supersonic one by converting the ion thermal energy to the flow energy. The results are compared with the prediction by a1-D isentropic flow model

  17. The effect of nozzle location on the concentration profiles in chemical addition tank

    International Nuclear Information System (INIS)

    Park, B. H.; Kim, E. K.; Ro, T. S.; Lee, C. H.

    2001-01-01

    A numerical analysis of the flow and injection characteristics is performed for the flow field created by water injected into a cylindrical tank with an initially stationary fluid. The flow is relevant to the operation of the chemical addition system in the chemical and volume control system( CVCS) of nuclear power plants. This study is performed to improve the current design which has a disk block inside tank. The numerical analysis for the flow and injection characteristics in chemical addition tank are carried out using CFD code FLUENT 5. Results show that the inlet nozzle installed in tangential direction at the uppermost region of the tank cylinder and the outlet nozzle located at the center of the tank bottom is very effective in enhancing the injection in the tank

  18. Effects of Fuel and Nozzle Characteristics on Micro Gas Turbine System: A Review

    Science.gov (United States)

    Akasha Hashim, Muhammad; Khalid, Amir; Salleh, Hamidon; Sunar, Norshuhaila Mohamed

    2017-08-01

    For many decades, gas turbines have been used widely in the internal combustion engine industry. Due to the deficiency of fossil fuel and the concern of global warming, the used of bio-gas have been recognized as one of most clean fuels in the application of engine to improve performance of lean combustion and minimize the production of NOX and PM. This review paper is to understand the combustion performance using dual-fuel nozzle for a micro gas turbine that was basically designed as a natural gas fuelled engine, the nozzle characteristics of the micro gas turbine has been modelled and the effect of multi-fuel used were investigated. The used of biogas (hydrogen) as substitute for liquid fuel (methane) at constant fuel injection velocity, the flame temperature is increased, but the fuel low rate reduced. Applying the blended fuel at constant fuel rate will increased the flame temperature as the hydrogen percentages increased. Micro gas turbines which shows the uniformity of the flow distribution that can be improved without the increase of the pressure drop by applying the variable nozzle diameters into the fuel supply nozzle design. It also identifies the combustion efficiency, better fuel mixing in combustion chamber using duel fuel nozzle with the largest potential for the future. This paper can also be used as a reference source that summarizes the research and development activities on micro gas turbines.

  19. Development of ABWR inertia-increased reactor internal pump and thicker sleeve nozzle

    International Nuclear Information System (INIS)

    Takahashi, Shirou; Shiina, Kouji; Matsumura, Seiichi

    2002-01-01

    The conventional reactor internal pumps (RIPs) in the ABWR have an inertia moment coming from the shafts and Motor-Generator sets, enabling the RIPs to continue running for a few seconds, when a trip of all RIPs event occurs. It is possible to simplify the RIPs' power supply system without affecting the core flow supply when the above event occurs by eliminating M-G sets, if the rotating inertia is increased. This inertia increase due to an additional flywheel, which leads to gains in weight and length, requires the larger diameter nozzle with the thicker sleeve. However, too large a nozzle diameter may change the hydraulic performance. In authors' previous study, the optimum nozzle diameter (492 mm) was selected through 1/5-scale test. In this study, the 492 mm nozzle and the inertia-increased RIP were verified through the full-scale tests. The rotating inertia time constant on coastdown characteristics (behavior of the RIP speed in the event of power loss) for the inertia-increased RIP doubled compared with the current RIP. The casing and the shaft vibration were also confirmed to satisfy the design criteria. Moreover, hydraulic performance and heat increase in the motor casing due to the flywheel were evaluated. The inertia increased RIP with the 492 mm nozzle maintained good performance. (author)

  20. Preliminary Results and Learning Curve of the Minimally Invasive Chevron Akin Operation for Hallux Valgus.

    Science.gov (United States)

    Jowett, Charlie R J; Bedi, Harvinder S

    Minimally invasive surgery is increasing in popularity. It is relevant in hallux valgus surgery owing to the potential for reduced disruption of the soft tissues and improved wound healing. We present our results and assess the learning curve of the minimally invasive Chevron Akin operation for hallux valgus. A total of 120 consecutive feet underwent minimally invasive Chevron Akin for symptomatic hallux valgus, of which 14 were excluded. They were followed up for a mean of 25 (range 18 to 38) months. The patients were clinically assessed using the American Orthopaedic Foot and Ankle Society score. Complications and patient satisfaction were recorded. The radiographs were analyzed and measurements recorded for hallux valgus and intermetatarsal angle correction. The mean age of the patients undergoing surgery was 55 (range 25 to 81) years. Of the 78 patients, 76 (97.4%) were female and 2 (2.6%) were male; 28 (35.9%) cases were bilateral. The mean American Orthopaedic Foot and Ankle Society score improved from 56 (range 23 to 76) preoperatively to 87 (range 50 to 100) postoperatively (p technique. They display a steep associated learning curve. However, the results are promising, and the learning curve is comparable to that for open hallux valgus surgery. Copyright © 2017 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  1. Cyclic Testing of Steel Chevron Braces with Vertically Slotted Beam Connection

    Directory of Open Access Journals (Sweden)

    Rozlyn K. Bubela

    2010-07-01

    Full Text Available Experimental tests were performed to study the seismic behavior and performance of modified steel chevron braced frame systems, which incorporate a vertical slotted connection (VSC detail between the top of the braces and the floor beam above. The VSC detail is intended to prevent vertical load transfer to the beam and limit brace forces to the compressive resistance of the members. Full-scale quasi-static cyclic tests were performed on two specimens with hollow tube braces, with one specimen having the braces filled with concrete. Both frames exhibited stable, predictable behavior under cyclic loading. The VSC detail provided free vertical movement of the brace assembly during both tests. However, its flexibility created a moderate reduction in the overall lateral stiffness of the frame. The concrete-filled tube specimen sustained higher peak loads, demonstrated greater residual strength and dissipated more energy than the hollow tube specimen due to the partial inhibition of local buckling by the concrete core. It was found that the VSC chevron braced frame system is a suitable concept for use in buildings in high-risk seismic zones.

  2. The Chevron Foil Thrust Bearing: Improved Performance Through Passive Thermal Management and Effective Lubricant Mixing

    Science.gov (United States)

    Bruckner, Robert

    2013-01-01

    An improved foil thrust bearing is described that eliminates or reduces the need for forced cooling of the bearing foils while at the same time improves the load capacity of the bearing, enhances damping, provides overload tolerance, and eliminates the high speed load capacity drop-off that plagues the current state of the art. The performance improvement demonstrated by the chevron foil thrust bearing stems from a novel trailing edge shape that splays the hot lubricant in the thin film radially, thus preventing hot lubricant carry-over into the ensuing bearing sector. Additionally, the chevron shaped trailing edge induces vortical mixing of the hot lubricant with the gas that is naturally resident within the inter-pad region of a foil thrust bearing. The elimination of hot gas carry-over in combination with the enhanced mixing has enabled a completely passive thermally managed foil bearing design. Laboratory testing at NASA has confirmed the original analysis and reduced this concept to practice.

  3. Li/Li2 supersonic nozzle beam

    International Nuclear Information System (INIS)

    Wu, C.Y.R.; Crooks, J.B.; Yang, S.C.; Way, K.R.; Stwalley, W.C.

    1977-01-01

    The characterization of a lithium supersonic nozzle beam was made using spectroscopic techniques. It is found that at a stagnation pressure of 5.3 kPa (40 torr) and a nozzle throat diameter of 0.4 mm the ground state vibrational population of Li 2 can be described by a Boltzmann distribution with T/sub v/ = 195 +- 30 0 K. The rotational temperature is found to be T/sub r/ = 70 +- 20 0 K by band shape analysis. Measurements by quadrupole mass spectrometer indicates that approximately 10 mole per cent Li 2 dimers are formed at an oven body temperature of 1370 0 K n the supersonic nozzle expansion. This measured mole fraction is in good agreement with the existing dimerization theory

  4. Dual-nozzle microfluidic droplet generator

    Science.gov (United States)

    Choi, Ji Wook; Lee, Jong Min; Kim, Tae Hyun; Ha, Jang Ho; Ahrberg, Christian D.; Chung, Bong Geun

    2018-05-01

    The droplet-generating microfluidics has become an important technique for a variety of applications ranging from single cell analysis to nanoparticle synthesis. Although there are a large number of methods for generating and experimenting with droplets on microfluidic devices, the dispensing of droplets from these microfluidic devices is a challenge due to aggregation and merging of droplets at the interface of microfluidic devices. Here, we present a microfluidic dual-nozzle device for the generation and dispensing of uniform-sized droplets. The first nozzle of the microfluidic device is used for the generation of the droplets, while the second nozzle can accelerate the droplets and increase the spacing between them, allowing for facile dispensing of droplets. Computational fluid dynamic simulations were conducted to optimize the design parameters of the microfluidic device.

  5. A Sensor-Based Visual Effect Evaluation of Chevron Alignment Signs’ Colors on Drivers through the Curves in Snow and Ice Environment

    Directory of Open Access Journals (Sweden)

    Wei Zhao

    2017-01-01

    Full Text Available The ability to quantitatively evaluate the visual feedback of drivers has been considered as the primary research for reducing crashes in snow and ice environments. Different colored Chevron alignment signs cause diverse visual effect. However, the effect of Chevrons on visual feedback and on the driving reaction while navigating curves in SI environments has not been adequately evaluated. The objective of this study is twofold: (1 an effective and long-term experiment was designed and developed to test the effect of colored Chevrons on drivers’ vision and vehicle speed; (2 a new quantitative effect evaluation model is employed to measure the effect of different colors of the Chevrons. Fixation duration and pupil size were used to describe the driver’s visual response, and Cohen’s d was used to evaluate the colors’ psychological effect on drivers. The results showed the following: (1 after choosing the proper color for Chevrons, drivers reduced the speed of the vehicle while approaching the curves. (2 It was easier for drivers to identify the road alignment after setting the Chevrons. (3 Cohen’s d related to different colors of Chevrons have different effect sizes. The conclusions provide evident references for freeway warning products and the design of intelligent vehicles.

  6. Biannular Airbreathing Nozzle Rig (BANR) facility checkout and plug nozzle performance test data

    Science.gov (United States)

    Cummings, Chase B.

    2010-09-01

    The motivation for development of a supersonic business jet (SSBJ) platform lies in its ability to create a paradigm shift in the speed and reach of commercial, private, and government travel. A full understanding of the performance capabilities of exhaust nozzle configurations intended for use in potential SSBJ propulsion systems is critical to the design of an aircraft of this type. Purdue University's newly operational Biannular Airbreathing Nozzle Rig (BANR) is a highly capable facility devoted to the testing of subscale nozzles of this type. The high accuracy, six-axis force measurement system and complementary mass flowrate measurement capabilities of the BANR facility make it rather ideally suited for exhaust nozzle performance appraisal. Detailed accounts pertaining to methods utilized in the proper checkout of these diagnostic capabilities are contained herein. Efforts to quantify uncertainties associated with critical BANR test measurements are recounted, as well. Results of a second hot-fire test campaign of a subscale Gulfstream Aerospace Corporation (GAC) axisymmetric, shrouded plug nozzle are presented. Determined test article performance parameters (nozzle thrust efficiencies and discharge coefficients) are compared to those of a previous test campaign and numerical simulations of the experimental set-up. Recently acquired data is compared to published findings pertaining to plug nozzle experiments of similar scale and operating range. Suggestions relating to the future advancement and improvement of the BANR facility are provided. Lessons learned with regards to test operations and calibration procedures are divulged in an attempt to aid future facility users, as well.

  7. Preliminary study of the primary nozzle position of a supersonic air ejector with a constant-area mixing chamber

    Directory of Open Access Journals (Sweden)

    Kracik Jan

    2017-01-01

    Full Text Available This work aims at investigating the primary nozzle position in a proposed supersonic air ejector device. The ejector is primarily made up of a supersonic primary nozzle, which is located in the axis of the ejector, a suction chamber or secondary stream inlet, a mixing chamber and a diffuser. The ejector design allows to translate the primary nozzle in the axis direction and fix it in a chosen distance from the beginning of the mixing chamber and hence influence the secondary mass flow rate. In a limit case, it is possible to set the nozzle to such a position where no secondary flow occurs. If we ignore the case where no secondary flow occurs, five different nozzle distances have been investigated in this paper. Some cases seem to be alike and there are no significant dissimilarities between them. Courses of relative back-pressure ratio are carried out against the entrainment ratio and transition between on-design and off-design regimes is determined. Measurements of the mixed flow based on the standard ISO 5167 are performed by means of orifice plate method. In addition, a comparison between experiments and simulations performed by Ansys Fluent software is presented in order to indicate further improvements to the numerical model.

  8. Combustor nozzles in gas turbine engines

    Science.gov (United States)

    Johnson, Thomas Edward; Keener, Christopher Paul; Stewart, Jason Thurman; Ostebee, Heath Michael

    2017-09-12

    A micro-mixer nozzle for use in a combustor of a combustion turbine engine, the micro-mixer nozzle including: a fuel plenum defined by a shroud wall connecting a periphery of a forward tube sheet to a periphery of an aft tubesheet; a plurality of mixing tubes extending across the fuel plenum for mixing a supply of compressed air and fuel, each of the mixing tubes forming a passageway between an inlet formed through the forward tubesheet and an outlet formed through the aft tubesheet; and a wall mixing tube formed in the shroud wall.

  9. LEAK AND GAS PERMEABILITY TESTING DURING SOIL-GAS SAMPLING AT HAL'S CHEVRON LUST SITE IN GREEN RIVER, UTAH

    Science.gov (United States)

    The results of gas permeability and leak testing during active soil-gas sampling at Hal’s Chevron LUST Site in Green River, Utah are presented. This study was conducted to support development of a passive soil-gas sampling method. Gas mixtures containing helium and methane were...

  10. Equivalent correction in scarf and chevron osteotomy in moderate and severe hallux valgus: a randomized controlled trial.

    NARCIS (Netherlands)

    Deenik, A.; Mameren, H. van; Visser, E. de; Waal Malefijt, M.C. de; Draijer, F.; Bie, R. de

    2008-01-01

    BACKGROUND: Chevron osteotomy is a widely accepted osteotomy for correction of hallux valgus.(18) Algorithms were developed to overcome the limitations of distal osteotomies. Scarf osteotomy has become popular as a versatile procedure that should be able to correct most cases of acquired hallux

  11. Research Amplitudo Vibration On Holder Due To The Process Of Lathe Nozzle Rocket RX 450

    Science.gov (United States)

    Ediwan; Budi Djatmiko, Agus; Dody Arisandi, EfFendy; Purnomo, Heri; Ibadi, Mahfud

    2018-04-01

    The main function of the rocket nozzle is to convert the enthalpy efficiency from combustion gas to kinetic energy and also to make high velocity out of the gas. The rocket nozzle usually consists of a converging and diverging part. With a smaller area on the neck and enlarged at the exit area. The velocity flow through the nozzle enlarges into the speed of sound through the neck and then becomes super sonic in the divergent part. Nozzle making or machining using conventional lathes, first performed is drilling on a massive metal that is bonded to the veneer, then after a sufficient gap is done deep-boring. At the time of the process of lathe in the nozzle RX 450 there is an obstacle that is vibrating tool holder chisel or holder so it is worried about not precision of the process of lathe. This should not happen because it can cause failure in the latter for it needs to be studied and studied further so that the lathe process goes accordingly. The holder material of ST 60 with a modulus of elasticity 200 GPa and a nozzle material of AISI 4340 alloy steel with σyield = 470 MPa, Shear Modulus G = 80 GPa. The purpose of this research is to observe the amplitude of vibration on the holder due to RX- 450 nozzle lathe processing for the purpose of amplitude that occurs in accordance with the desired so that the nozzle structure is no damage process. The result of the research was obtained holder with length (L) 80cm, profile width (B) 5 cm, height of profile (H) 10 cm, turning machine ω = 8.98 rad / sec and natural holder frequency ωn = 89.8 rad / second, Amplitude of vibration of δ = 1.21 mm, while the amplitude of the design X = 1.22 mm From the results of this study it can be said that the holder of a chisel or holder can be used as a tool at the time of RX nozzle retrieval process and is quite safe because it works under the condition ω/ω n Rocket Payload "AKPV Engineering University of Wyoming 2009 )

  12. Effect of Injector Nozzle Holes on Diesel Engine Performance

    OpenAIRE

    Semin,; Yusof, Mohd Yuzri Mohd; Arof, Aminuddin Md; Shaharudin, Daneil Tomo; Ismail, Abdul Rahim

    2010-01-01

    All of the injector nozzle holes have examined and the results are shown that the seven holes nozzle have provided the best burning result for the fuel in-cylinder burned in any different engine speeds and the best burning is in low speed engine. In engine performance effect, all of the nozzles have examined and the five holes nozzle provided the best result in indicted power, indicated torque and ISFC in any different engine speeds.

  13. Development of an integrated optical coherence tomography-gas nozzle system for surgical laser ablation applications: preliminary findings of in situ spinal cord deformation due to gas flow effects.

    Science.gov (United States)

    Wong, Ronnie; Jivraj, Jamil; Vuong, Barry; Ramjist, Joel; Dinn, Nicole A; Sun, Cuiru; Huang, Yize; Smith, James A; Yang, Victor X D

    2015-01-01

    Gas assisted laser machining of materials is a common practice in the manufacturing industry. Advantages in using gas assistance include reducing the likelihood of flare-ups in flammable materials and clearing away ablated material in the cutting path. Current surgical procedures and research do not take advantage of this and in the case for resecting osseous tissue, gas assisted ablation can help minimize charring and clear away debris from the surgical site. In the context of neurosurgery, the objective is to cut through osseous tissue without damaging the underlying neural structures. Different inert gas flow rates used in laser machining could cause deformations in compliant materials. Complications may arise during surgical procedures if the dura and spinal cord are damaged by these deformations. We present preliminary spinal deformation findings for various gas flow rates by using optical coherence tomography to measure the depression depth at the site of gas delivery.

  14. Evolutionary Optimization of Centrifugal Nozzles for Organic Vapours

    Science.gov (United States)

    Persico, Giacomo

    2017-03-01

    This paper discusses the shape-optimization of non-conventional centrifugal turbine nozzles for Organic Rankine Cycle applications. The optimal aerodynamic design is supported by the use of a non-intrusive, gradient-free technique specifically developed for shape optimization of turbomachinery profiles. The method is constructed as a combination of a geometrical parametrization technique based on B-Splines, a high-fidelity and experimentally validated Computational Fluid Dynamic solver, and a surrogate-based evolutionary algorithm. The non-ideal gas behaviour featuring the flow of organic fluids in the cascades of interest is introduced via a look-up-table approach, which is rigorously applied throughout the whole optimization process. Two transonic centrifugal nozzles are considered, featuring very different loading and radial extension. The use of a systematic and automatic design method to such a non-conventional configuration highlights the character of centrifugal cascades; the blades require a specific and non-trivial definition of the shape, especially in the rear part, to avoid the onset of shock waves. It is shown that the optimization acts in similar way for the two cascades, identifying an optimal curvature of the blade that both provides a relevant increase of cascade performance and a reduction of downstream gradients.

  15. Sauter mean diameter statistics of the starch dispersion atomized with hydraulic nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Naz, Muhammad Yasin, E-mail: yasin603@yahoo.com; Ariwahjoedi, Bambang, E-mail: bambang-ariwahjoedi@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Sulaiman, Shaharin Anwar, E-mail: shaharin@petronas.com.my [Department Mechanical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2015-07-22

    In the reported research work, the microscopic droplet velocity at different axial and radial locations downstream to the nozzle exit was studied by using a non-intrusive Laser Doppler Anemometry (LDA) techniques. These velocity measurements made in the viscous fluid spray sterams were used to predict the different breakup regimes in the flow. It was noticed that the droplet velocity decreased sharply downstream to the nozzle exit, whereas steady decrease in velocity was seen along the radial directions. For shorter injection time periods, the velocity downstream to the nozzle was not following the general breakup model. However, along the radial direction it exactly followed the discussed model. Along the spray centerline, the velocity was decreasing sharply even at far points from the nozzle exit. It was difficult to identify the core region, transition region and fully developed spray region in the flow. It revealed that the jet breakup was not completed yet and further disintegration was taking place along the spray centerline for shorter injection periods below 250 ms.

  16. Sauter mean diameter statistics of the starch dispersion atomized with hydraulic nozzle

    International Nuclear Information System (INIS)

    Naz, Muhammad Yasin; Ariwahjoedi, Bambang; Sulaiman, Shaharin Anwar

    2015-01-01

    In the reported research work, the microscopic droplet velocity at different axial and radial locations downstream to the nozzle exit was studied by using a non-intrusive Laser Doppler Anemometry (LDA) techniques. These velocity measurements made in the viscous fluid spray sterams were used to predict the different breakup regimes in the flow. It was noticed that the droplet velocity decreased sharply downstream to the nozzle exit, whereas steady decrease in velocity was seen along the radial directions. For shorter injection time periods, the velocity downstream to the nozzle was not following the general breakup model. However, along the radial direction it exactly followed the discussed model. Along the spray centerline, the velocity was decreasing sharply even at far points from the nozzle exit. It was difficult to identify the core region, transition region and fully developed spray region in the flow. It revealed that the jet breakup was not completed yet and further disintegration was taking place along the spray centerline for shorter injection periods below 250 ms

  17. Load calculation on the nozzle in a flue gas desulphurization system

    Science.gov (United States)

    Róbert, Olšiak; Zoltán, Fuszko; Zoltán, Csuka

    2017-09-01

    The desulphurization system is used to remove sulfur oxides from exhaust, so-called flue gases through absorbing them via the sprayed suspension. The suspension delivered from the pump system to the atmospheric bi-directional double hollow cone nozzle has the prescribed working pressure. The unknown mechanical load on the solid body of the nozzle is present through the change of moment due to the flow of the suspension through the bi-directional outflow areas [1], [4]. The calculation of the acting forces and torques in the 3 directions was carried out with the methods of computational fluid dynamics (CFD) in the software ANSYS Fluent. The geometric model of the flow areas of the nozzle were created with the methods of reverse engineering. The computational mesh required by the CFD solver was created, and its quality verified with the standard criteria. The used boundary conditions were defined by the hydraulic parameters of the pump system, the properties of the suspension present in the hydraulic system were specified by sample analysis. The post-processed and analyzed results of the CFD calculation, the pressure-field and the velocity magnitudes in particular directions were further used as input parameters at the mechanical analysis of the load on the bi-directional nozzle.

  18. Sauter mean diameter statistics of the starch dispersion atomized with hydraulic nozzle

    Science.gov (United States)

    Naz, Muhammad Yasin; Sulaiman, Shaharin Anwar; Ariwahjoedi, Bambang

    2015-07-01

    In the reported research work, the microscopic droplet velocity at different axial and radial locations downstream to the nozzle exit was studied by using a non-intrusive Laser Doppler Anemometry (LDA) techniques. These velocity measurements made in the viscous fluid spray sterams were used to predict the different breakup regimes in the flow. It was noticed that the droplet velocity decreased sharply downstream to the nozzle exit, whereas steady decrease in velocity was seen along the radial directions. For shorter injection time periods, the velocity downstream to the nozzle was not following the general breakup model. However, along the radial direction it exactly followed the discussed model. Along the spray centerline, the velocity was decreasing sharply even at far points from the nozzle exit. It was difficult to identify the core region, transition region and fully developed spray region in the flow. It revealed that the jet breakup was not completed yet and further disintegration was taking place along the spray centerline for shorter injection periods below 250 ms.

  19. Transient Three-Dimensional Analysis of Side Load in Liquid Rocket Engine Nozzles

    Science.gov (United States)

    Wang, Ten-See

    2004-01-01

    Three-dimensional numerical investigations on the nozzle start-up side load physics were performed. The objective of this study is to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, and pressure-based computational fluid dynamics formulation, and a simulated inlet condition based on a system calculation. Finite-rate chemistry was used throughout the study so that combustion effect is always included, and the effect of wall cooling on side load physics is studied. The side load physics captured include the afterburning wave, transition from free- shock to restricted-shock separation, and lip Lambda shock oscillation. With the adiabatic nozzle, free-shock separation reappears after the transition from free-shock separation to restricted-shock separation, and the subsequent flow pattern of the simultaneous free-shock and restricted-shock separations creates a very asymmetric Mach disk flow. With the cooled nozzle, the more symmetric restricted-shock separation persisted throughout the start-up transient after the transition, leading to an overall lower side load than that of the adiabatic nozzle. The tepee structures corresponding to the maximum side load were addressed.

  20. Shock wave fabricated ceramic-metal nozzles

    NARCIS (Netherlands)

    Carton, E.P.; Stuivinga, M.E.C.; Keizers, H.L.J.; Verbeek, H.J.; Put, P.J. van der

    1999-01-01

    Shock compaction was used in the fabrication of high temperature ceramic-based materials. The materials' development was geared towards the fabrication of nozzles for rocket engines using solid propellants, for which the following metal-ceramic (cermet) materials were fabricated and tested: B4C-Ti

  1. New atomization nozzle for spray drying

    NARCIS (Netherlands)

    Deventer, H.C. van; Houben, R.J.; Koldeweij, R.B.J.

    2013-01-01

    A new atomization nozzle based on ink jet technology is introduced for spray drying. Application areas are the food and dairy industry, in the first instance, because in these industries the quality demands on the final powders are high with respect to heat load, powder shape, and size distribution.

  2. Clamp and Gas Nozzle for TIG Welding

    Science.gov (United States)

    Gue, G. B.; Goller, H. L.

    1982-01-01

    Tool that combines clamp with gas nozzle is aid to tungsten/inert-gas (TIG) welding in hard-to-reach spots. Tool holds work to be welded while directing a stream of argon gas at weld joint, providing an oxygen-free environment for tungsten-arc welding.

  3. Microalgal cell disruption via ultrasonic nozzle spraying.

    Science.gov (United States)

    Wang, M; Yuan, W

    2015-01-01

    The objective of this study was to understand the effect of operating parameters, including ultrasound amplitude, spraying pressure, nozzle orifice diameter, and initial cell concentration on microalgal cell disruption and lipid extraction in an ultrasonic nozzle spraying system (UNSS). Two algal species including Scenedesmus dimorphus and Nannochloropsis oculata were evaluated. Experimental results demonstrated that the UNSS was effective in the disruption of microalgal cells indicated by significant changes in cell concentration and Nile red-stained lipid fluorescence density between all treatments and the control. It was found that increasing ultrasound amplitude generally enhanced cell disruption and lipid recovery although excessive input energy was not necessary for best results. The effect of spraying pressure and nozzle orifice diameter on cell disruption and lipid recovery was believed to be dependent on the competition between ultrasound-induced cavitation and spraying-generated shear forces. Optimal cell disruption was not always achieved at the highest spraying pressure or biggest nozzle orifice diameter; instead, they appeared at moderate levels depending on the algal strain and specific settings. Increasing initial algal cell concentration significantly reduced cell disruption efficiency. In all UNSS treatments, the effectiveness of cell disruption and lipid recovery was found to be dependent on the algal species treated.

  4. Design criteria for piping and nozzles program

    International Nuclear Information System (INIS)

    Moore, S.E.; Bryson, J.W.

    1977-01-01

    This report reviews the activities and accomplishments of the Design Criteria for Piping and Nozzles program being conducted by the Oak Ridge National Laboratory for the period July 1, 1975, to September 30, 1976. The objectives of the program are to conduct integrated experimental and analytical stress analysis studies of piping system components and isolated and closely-spaced pressure vessel nozzles in order to confirm and/or improve the adequacy of structural design criteria and analytical methods used to assure the safe design of nuclear power plants. Activities this year included the development of a finite-element program for analyzing two closely spaced nozzles in a cylindrical pressure vessel; a limited-parameter study of vessels with isolated nozzles, finite-element studies of piping elbows, a fatigue test of an out-of-round elbow, summary and evaluation of experimental studies on the elastic-response and fatigue failure of tees, parameter studies on the behavior of flanged joints, publication of fifteen topical reports and papers on various experimental and analytical studies; and the development and acceptance of a number of design rules changes to the ASME Code. 2 figures, 2 tables

  5. Nozzle erosion characterization and minimization for high-pressure rocket motor applications

    Science.gov (United States)

    Evans, Brian

    Understanding of the processes that cause nozzle throat erosion and developing methods for mitigation of erosion rate can allow higher operating pressures for advanced rocket motors. However, erosion of the nozzle throat region, which is a strong function of operating pressure, must be controlled to realize the performance gains of higher operating pressures. The objective of this work was the study the nozzle erosion rates at a broad range of pressures from 7 to 34.5 MPa (1,000 to 5,000 psia) using two different rocket motors. The first is an instrumented solidpropellant motor (ISPM), which uses two baseline solid propellants; one is a non-metallized propellant called Propellant S and the other is a metallized propellant called Propellant M. The second test rig is a non-metallized solid-propellant rocket motor simulator (RMS). The RMS is a gas rocket with the ability to vary the combustion-product species composition by systematically varying the flow rates of gaseous reactants. Several reactant mixtures were utilized in the study to determine the relative importance of different oxidizing species (such as H2O, OH, and CO2). Both test rigs are equipped with a windowed nozzle section for real-time X-ray radiography diagnostics of the instantaneous throat variations for deducing the instantaneous erosion rates. The nozzle test section for both motors can also incorporate a nozzle boundary-layer control system (NBLCS) as a means of nozzle erosion mitigation. The effectiveness of the NBLCS at preventing nozzle throat erosion was demonstrated for both the RMS and the ISPM motors at chamber pressures up to 34 MPa (4930 psia). All tests conducted with the NBLCS showed signs of coning of the propellant surface, leading to increased mass burning rate and resultant chamber pressure. Two correlations were developed for the nozzle erosion rates from solid propellant testing, one for metallized propellant and one for non-metallized propellants. The non-metallized propellant

  6. Proximal Intermetatarsal Divergence in Distal Chevron Osteotomy for Hallux Valgus: An Overlooked Finding.

    Science.gov (United States)

    Akpinar, Evren; Buyuk, Abdul Fettah; Cetinkaya, Engin; Gursu, Sarper; Ucpunar, Hanifi; Albayrak, Akif

    2016-01-01

    The goal of distal chevron osteotomy for hallux valgus is to restore proper first-toe joint alignment by performing lateral translation of the distal first metatarsal fragment (the metatarsal head). We hypothesized that in some patients this procedure might also result in involuntary medial translation of the proximal first metatarsal fragment, which we called proximal intermetatarsal divergence. The aim of the present study was to compare the pre- and postoperative radiographs of patients with hallux valgus to determine whether we could identify proximal intermetatarsal divergence. We retrospectively compared the pre- and postoperative radiographs of 29 feet in 28 patients treated with distal chevron osteotomy. Two different methods were used to measure the intermetatarsal angles: the anatomic intermetatarsal angle (aIMA) and the mechanical intermetatarsal angle (mIMA). The maximum intermetatarsal distance (MID) was also measured. We defined proximal intermetatarsal divergence as a postoperative increase in the aIMA or MID, coupled with a decrease in the mIMA. For data analysis, we divided the patients into low-angle (mild deformity) and high-angle (severe deformity) groups, according to their preoperative mIMA. The mean ± standard deviation patient age was 41 ± 14 years. In the low-angle group, the mean mIMA decreased (from 10.91° to 7.00°), the mean aIMA increased (from 11.80° to 13.55°), and the mean MID increased (from 17.97 mm to 20.60 mm; p = .001, for all). In the high-angle group, the mean mIMA decreased (from 14.30° to 6.90°; p = .001), the mean aIMA decreased (from 14.77° to 13.54°; p = .06), and the mean MID decreased (from 20.74 mm to 20.37 mm; p = .64). The results of our study suggest that proximal intermetatarsal divergence might occur after distal chevron osteotomy for hallux valgus, primarily in patients with a low preoperative mIMA. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All

  7. Model based decision support system of operating settings for MMAT nozzles

    Directory of Open Access Journals (Sweden)

    Fritz Bradley Keith

    2016-04-01

    Full Text Available Droplet size, which is affected by nozzle type, nozzle setups and operation, and spray solution, is one of the most critical factors influencing spray performance, environment pollution, food safety, and must be considered as part of any application scenario. Characterizing spray nozzles can be a timely and expensive proposition if the entire operational space (all combinations of spray pressure and orifice size, what influence flow rate is to be evaluated. This research proposes a structured, experimental design that allows for the development of computational models for droplet size based on any combination of a nozzle’s potential operational settings. The developed droplet size determination model can be used as Decision Support System (DSS for precise selection of sprayer working parameters to adapt to local field scenarios. Five nozzle types (designs were evaluated across their complete range of orifice size (flow rate* and spray pressures using a response surface experimental design. Several of the models showed high level fits of the modeled to the measured data while several did not as a result of the lack of significant effect from either orifice size (flow rate* or spray pressure. The computational models were integrated into a spreadsheet based user interface for ease of use. The proposed experimental design provides for efficient nozzle evaluations and development of computational models that allow for the determination of droplet size spectrum and spraying classification for any combination of a given nozzle’s operating settings. The proposed DSS will allow for the ready assessment and modification of a sprayers performance based on the operational settings, to ensure the application is made following recommendations in plant protection products (PPP labels.

  8. Experimental aerodynamic and acoustic model testing of the Variable Cycle Engine (VCE) testbed coannular exhaust nozzle system

    Science.gov (United States)

    Nelson, D. P.; Morris, P. M.

    1980-01-01

    Aerodynamic performance and jet noise characteristics of a one sixth scale model of the variable cycle engine testbed exhaust system were obtained in a series of static tests over a range of simulated engine operating conditions. Model acoustic data were acquired. Data were compared to predictions of coannular model nozzle performance. The model, tested with an without a hardwall ejector, had a total flow area equivalent to a 0.127 meter (5 inch) diameter conical nozzle with a 0.65 fan to primary nozzle area ratio and a 0.82 fan nozzle radius ratio. Fan stream temperatures and velocities were varied from 422 K to 1089 K (760 R to 1960 R) and 434 to 755 meters per second (1423 to 2477 feet per second). Primary stream properties were varied from 589 to 1089 K (1060 R to 1960 R) and 353 to 600 meters per second (1158 to 1968 feet per second). Exhaust plume velocity surveys were conducted at one operating condition with and without the ejector installed. Thirty aerodynamic performance data points were obtained with an unheated air supply. Fan nozzle pressure ratio was varied from 1.8 to 3.2 at a constant primary pressure ratio of 1.6; primary pressure ratio was varied from 1.4 to 2.4 while holding fan pressure ratio constant at 2.4. Operation with the ejector increased nozzle thrust coefficient 0.2 to 0.4 percent.

  9. A modified Austin/chevron osteotomy for treatment of hallux valgus and hallux rigidus.

    Science.gov (United States)

    Vasso, Michele; Del Regno, Chiara; D'Amelio, Antonio; Schiavone Panni, Alfredo

    2016-03-01

    The purpose of this brief paper is to present the preliminary results of a modified Austin/chevron osteotomy for treatment of hallux valgus and hallux rigidus. In this procedure, the dorsal arm of the osteotomy is performed orthogonal to the horizontal plane of the first metatarsal, the main advantage being that this allows much easier and more accurate multiplanar correction of first metatarsal deformities. From 2010 to 2013, 184 consecutive patients with symptomatic hallux valgus and 48 patients with hallux rigidus without severe metatarsophalangeal joint degeneration underwent such modified chevron osteotomy. Mean patient age was 54.9 (range 21-70) years, and mean follow-up duration was 41.7 (range 24-56) months. Ninety-three percent of patients were satisfied with the surgery. Mean American Orthopaedic Foot and Ankle Society (AOFAS) score improved from 56.6 preoperatively to 90.6 at last follow-up, and mean visual analog scale (VAS) pain score decreased from 5.7 preoperatively to 1.6 at final follow-up (p hallux valgus, mean hallux valgus angle decreased from 34.1° preoperatively to 6.2° at final follow-up, and mean intermetatarsal angle decreased from 18.5° preoperatively to 4.1° at final follow-up (p < 0.05). One patient developed postoperative transfer metatarsalgia, treated successfully with second-time percutaneous osteotomy of the minor metatarsals, whilst one patient had wound infection that resolved with systemic antibiotics. Level IV.

  10. Treatment of moderate hallux valgus by percutaneous, extra-articular reverse-L Chevron (PERC) osteotomy.

    Science.gov (United States)

    Lucas y Hernandez, J; Golanó, P; Roshan-Zamir, S; Darcel, V; Chauveaux, D; Laffenêtre, O

    2016-03-01

    The aim of this study was to report a single surgeon series of consecutive patients with moderate hallux valgus managed with a percutaneous extra-articular reverse-L chevron (PERC) osteotomy. A total of 38 patients underwent 45 procedures. There were 35 women and three men. The mean age of the patients was 48 years (17 to 69). An additional percutaneous Akin osteotomy was performed in 37 feet and percutaneous lateral capsular release was performed in 22 feet. Clinical and radiological assessments included the type of forefoot, range of movement, the American Orthopedic Foot and Ankle (AOFAS) score, a subjective rating and radiological parameters. The mean follow-up was 59.1 months (45.9 to 75.2). No patients were lost to follow-up. The mean AOFAS score increased from 62.5 (30 to 80) pre-operatively to 97.1 (75 to 100) post-operatively. A total of 37 patients (97%) were satisfied. At the last follow up there was a statistically significant decrease in the hallux valgus angle, the intermetatarsal angle and the proximal articular set angle. The range of movement of the first metatarsophalangeal joint improved significantly.. There was more improvement in the range of movement in patients who had fixation of the osteotomy of the proximal phalanx. Preliminary results of this percutaneous approach are promising. This technique is reliable and reproducible. Its main asset is that it maintains an excellent range of movement. The PERC osteotomy procedure is an effective approach for surgical management of moderate hallux valgus which combines the benefits of percutaneous surgery with the versatility of the chevron osteotomy whilst maintaining excellent first MTPJ range of motion. ©2016 The British Editorial Society of Bone & Joint Surgery.

  11. Nuclear thermal rocket nozzle testing and evaluation program

    International Nuclear Information System (INIS)

    Davidian, K.O.; Kacynski, K.J.

    1993-01-01

    Performance characteristics of the Nuclear Thermal Rocket can be enhanced through the use of unconventional nozzles as part of the propulsion system. In this report, the Nuclear Thermal Rocket nozzle testing and evaluation program being conducted at the NASA Lewis Research Center is outlined and the advantages of a plug nozzle are described. A facility description, experimental designs and schematics are given. Results of pretest performance analyses show that high nozzle performance can be attained despite substantial nozzle length reduction through the use of plug nozzles as compared to a convergent-divergent nozzle. Pretest measurement uncertainty analyses indicate that specific impulse values are expected to be within plus or minus 1.17%

  12. Gas dynamic virtual nozzle for generation of microscopic droplet streams

    Energy Technology Data Exchange (ETDEWEB)

    DePonte, D P; Weierstall, U; Schmidt, K; Warner, J; Starodub, D; Spence, J C H; Doak, R B [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States)], E-mail: dandeponte@gmail.com

    2008-10-07

    As shown by Ganan-Calvo (1998 Phys. Rev. Lett. 80 285-8), a free liquid jet can be compressed in diameter through gas dynamic forces exerted by a coaxially co-flowing gas, obviating the need for a solid nozzle to form a microscopic liquid jet and thereby alleviating the clogging problems that plague conventional droplet sources of small diameter. We describe in this paper a novel form of droplet beam source based on this principle. The source is miniature, robust, dependable, easily fabricated, essentially immune to clogging and eminently suitable for delivery of microscopic liquid droplets, including hydrated biological samples, into vacuum for analysis using vacuum instrumentation. Monodisperse, single-file droplet streams are generated by triggering the device with a piezoelectric actuator.

  13. Fuel injection nozzle and method of manufacturing the same

    Science.gov (United States)

    Monaghan, James Christopher; Johnson, Thomas Edward; Ostebee, Heath Michael

    2017-02-21

    A fuel injection head for use in a fuel injection nozzle comprises a monolithic body portion comprising an upstream face, an opposite downstream face, and a peripheral wall extending therebetween. A plurality of pre-mix tubes are integrally formed with and extend axially through the body portion. Each of the pre-mix tubes comprises an inlet adjacent the upstream face, an outlet adjacent the downstream face, and a channel extending between the inlet and the outlet. Each pre-mix tube also includes at least one fuel injector that at least partially extends outward from an exterior surface of the pre-mix tube, wherein the fuel injector is integrally formed with the pre-mix tube and is configured to facilitate fuel flow between the body portion and the channel.

  14. Ice Control with Brine Spread with Nozzles on Highways

    DEFF Research Database (Denmark)

    Bolet, Lars; Fonnesbech, Jens Kristian

    2010-01-01

    on the major roads (150 km) in the municipality of North Funen from the winter 2007/8. The result has been a dramatically reduction in the number of traffic accidents on slippery roads during the winter season. From 7 and 5 accidents in the previous 2 winters to 1 accident in the winter 2007/8. Neighbouring...... municipalities had an increasing number of traffic accidents on slippery roads in the same period.......During the years 1996-2006, the former county of Funen, Denmark, gradually replaced pre-wetted salt with brine spread with nozzles as anti-icing agent in all her ice control activities. The replacement related to 1000 kilometres of highways. Jeopardizing neither road safety nor traffic flow...

  15. Cathodoluminescence studies of chevron features in semi-polar (11 2 ¯ 2 ) InGaN/GaN multiple quantum well structures

    Science.gov (United States)

    Brasser, C.; Bruckbauer, J.; Gong, Y.; Jiu, L.; Bai, J.; Warzecha, M.; Edwards, P. R.; Wang, T.; Martin, R. W.

    2018-05-01

    Epitaxial overgrowth of semi-polar III-nitride layers and devices often leads to arrowhead-shaped surface features, referred to as chevrons. We report on a study into the optical, structural, and electrical properties of these features occurring in two very different semi-polar structures, a blue-emitting multiple quantum well structure, and an amber-emitting light-emitting diode. Cathodoluminescence (CL) hyperspectral imaging has highlighted shifts in their emission energy, occurring in the region of the chevron. These variations are due to different semi-polar planes introduced in the chevron arms resulting in a lack of uniformity in the InN incorporation across samples, and the disruption of the structure which could cause a narrowing of the quantum wells (QWs) in this region. Atomic force microscopy has revealed that chevrons can penetrate over 150 nm into the sample and quench light emission from the active layers. The dominance of non-radiative recombination in the chevron region was exposed by simultaneous measurement of CL and the electron beam-induced current. Overall, these results provide an overview of the nature and impact of chevrons on the luminescence of semi-polar devices.

  16. Multilaboratory particle image velocimetry analysis of the FDA benchmark nozzle model to support validation of computational fluid dynamics simulations.

    Science.gov (United States)

    Hariharan, Prasanna; Giarra, Matthew; Reddy, Varun; Day, Steven W; Manning, Keefe B; Deutsch, Steven; Stewart, Sandy F C; Myers, Matthew R; Berman, Michael R; Burgreen, Greg W; Paterson, Eric G; Malinauskas, Richard A

    2011-04-01

    This study is part of a FDA-sponsored project to evaluate the use and limitations of computational fluid dynamics (CFD) in assessing blood flow parameters related to medical device safety. In an interlaboratory study, fluid velocities and pressures were measured in a nozzle model to provide experimental validation for a companion round-robin CFD study. The simple benchmark nozzle model, which mimicked the flow fields in several medical devices, consisted of a gradual flow constriction, a narrow throat region, and a sudden expansion region where a fluid jet exited the center of the nozzle with recirculation zones near the model walls. Measurements of mean velocity and turbulent flow quantities were made in the benchmark device at three independent laboratories using particle image velocimetry (PIV). Flow measurements were performed over a range of nozzle throat Reynolds numbers (Re(throat)) from 500 to 6500, covering the laminar, transitional, and turbulent flow regimes. A standard operating procedure was developed for performing experiments under controlled temperature and flow conditions and for minimizing systematic errors during PIV image acquisition and processing. For laminar (Re(throat)=500) and turbulent flow conditions (Re(throat)≥3500), the velocities measured by the three laboratories were similar with an interlaboratory uncertainty of ∼10% at most of the locations. However, for the transitional flow case (Re(throat)=2000), the uncertainty in the size and the velocity of the jet at the nozzle exit increased to ∼60% and was very sensitive to the flow conditions. An error analysis showed that by minimizing the variability in the experimental parameters such as flow rate and fluid viscosity to less than 5% and by matching the inlet turbulence level between the laboratories, the uncertainties in the velocities of the transitional flow case could be reduced to ∼15%. The experimental procedure and flow results from this interlaboratory study (available

  17. Static investigation of two fluidic thrust-vectoring concepts on a two-dimensional convergent-divergent nozzle

    Science.gov (United States)

    Wing, David J.

    1994-01-01

    A static investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel of two thrust-vectoring concepts which utilize fluidic mechanisms for deflecting the jet of a two-dimensional convergent-divergent nozzle. One concept involved using the Coanda effect to turn a sheet of injected secondary air along a curved sidewall flap and, through entrainment, draw the primary jet in the same direction to produce yaw thrust vectoring. The other concept involved deflecting the primary jet to produce pitch thrust vectoring by injecting secondary air through a transverse slot in the divergent flap, creating an oblique shock in the divergent channel. Utilizing the Coanda effect to produce yaw thrust vectoring was largely unsuccessful. Small vector angles were produced at low primary nozzle pressure ratios, probably because the momentum of the primary jet was low. Significant pitch thrust vector angles were produced by injecting secondary flow through a slot in the divergent flap. Thrust vector angle decreased with increasing nozzle pressure ratio but moderate levels were maintained at the highest nozzle pressure ratio tested. Thrust performance generally increased at low nozzle pressure ratios and decreased near the design pressure ratio with the addition of secondary flow.

  18. CAN-DO, CFD-based Aerodynamic Nozzle Design and Optimization program for supersonic/hypersonic wind tunnels

    Science.gov (United States)

    Korte, John J.; Kumar, Ajay; Singh, D. J.; White, J. A.

    1992-01-01

    A design program is developed which incorporates a modern approach to the design of supersonic/hypersonic wind-tunnel nozzles. The approach is obtained by the coupling of computational fluid dynamics (CFD) with design optimization. The program can be used to design a 2D or axisymmetric, supersonic or hypersonic, wind-tunnel nozzles that can be modeled with a calorically perfect gas. The nozzle design is obtained by solving a nonlinear least-squares optimization problem (LSOP). The LSOP is solved using an iterative procedure which requires intermediate flowfield solutions. The nozzle flowfield is simulated by solving the Navier-Stokes equations for the subsonic and transonic flow regions and the parabolized Navier-Stokes equations for the supersonic flow regions. The advantages of this method are that the design is based on the solution of the viscous equations eliminating the need to make separate corrections to a design contour, and the flexibility of applying the procedure to different types of nozzle design problems.

  19. Reactor vessel nozzle cracks: a photoelastic study

    International Nuclear Information System (INIS)

    Smith, C.W.

    1979-01-01

    A method consisting of a marriage between the ''frozen stress'' photoelastic approach and the local stress field equations of linear elastic fracture mechanics for estimating stress intensity factor distributions in three dimensional, finite cracked body problems is reviewed and extensions of the method are indicated. The method is then applied to the nuclear reactor vessel nozzle corner crack problem for both Intermediate Test Vessel and Boiling Water Reactor geometries. Results are compared with those of other investigators. 35 refs

  20. Research on characteristics of varying conditions for nozzle governing stage based on dimensional analysis

    International Nuclear Information System (INIS)

    Xu, Jian-qun; Ma, Lin; Sun, You-yuan; Cao, Zu-qing

    2014-01-01

    In this paper, thermodynamic calculations of nozzle governing stage are taken based on APROS (Advanced Process Simulation), and verify through the comparison of experiment table data. The influence of partial admission on pressure ratio within the governing stage is also analyzed. The results show that partial admission not only leads to partial admission losses, but also makes an impact on pressure ratio, enthalpy and reaction degree, in turn, causes the change of efficiency. Then, the nozzle pressure ratio after the full-open valve and semi-open valve respectively, is expressed as a function of flow ratio based on dimensional analysis. This paper presents a method of thermodynamic calculation for nozzle governing stage. Comparing with the results calculated through APROS and discussing the change of pressure ratio and reaction degree, it shows that the method can reflect the influence of partial admission on pressure ratio exactly, and further improve the accuracy of existing thermodynamic calculation. - Highlights: • Partial admission is an important factor that affects the characteristics of governing stage. • Simulated test together with thermodynamic calculation to build a simplified efficiency model. • A method of thermodynamic calculation for nozzle governing stage is also proposed in this paper. • This presented method is successfully applied to a 600 MW steam turbine unit

  1. Computational study of a High Pressure Turbine Nozzle/Blade Interaction

    Science.gov (United States)

    Kopriva, James; Laskowski, Gregory; Sheikhi, Reza

    2015-11-01

    A downstream high pressure turbine blade has been designed for this study to be coupled with the upstream uncooled nozzle of Arts and Rouvroit [1992]. The computational domain is first held to a pitch-line section that includes no centrifugal forces (linear sliding-mesh). The stage geometry is intended to study the fundamental nozzle/blade interaction in a computationally cost efficient manner. Blade/Nozzle count of 2:1 is designed to maintain computational periodic boundary conditions for the coupled problem. Next the geometry is extended to a fully 3D domain with endwalls to understand the impact of secondary flow structures. A set of systematic computational studies are presented to understand the impact of turbulence on the nozzle and down-stream blade boundary layer development, resulting heat transfer, and downstream wake mixing in the absence of cooling. Doing so will provide a much better understanding of stage mixing losses and wall heat transfer which, in turn, can allow for improved engine performance. Computational studies are performed using WALE (Wale Adapted Local Eddy), IDDES (Improved Delayed Detached Eddy Simulation), SST (Shear Stress Transport) models in Fluent.

  2. Stress analysis of PCV nozzle junction

    International Nuclear Information System (INIS)

    Uchiyama, Shoichi; Oikawa, Tsuneo; Hoshino, Seizo

    1976-01-01

    Most of various pressure vessels comprise each one cylindrical shell and one or more nozzles. In this study, in order to analyze the stress in the structures of this type as minutely and exactly as possible, the program for stress analysis by the finite element method was made, which is required for the strength analysis for three-dimensional structures. Especially, the problem of the stress distribution around nozzle junctions was solved theoretically with the program. The program for the analysis developed in this study is provided with various functions, such as the input generator for cylindrical, conical and spherical shells, and plotter, and is very covenient. The accuracy of analysis is very good. The method of analysis and the calculation of the rigidity matrices for the deformation in plane and bending are explained. The result of the stress analysis around the nozzle junctions of a containment vessel with this program was in good agreement with experimental data and the result with SAP-4 code, therefore the propriety of the calculated result with this program was proved. Also calculations were carried out on three cases, namely a flat plate fixed at one end with distributed load, a cylinder fixed at one end with internal pressure, and an I-beam fixed at one end with concentrated load. The calculated results agreed well with theoretical solutions in all cases. (Kako, I.)

  3. Pengaruh Jarak dan Posisi Nozzle Terhadap Daya Turbin Pelton

    Directory of Open Access Journals (Sweden)

    Yani Kurniawan

    2017-12-01

    Full Text Available Pelton Turbine is a turbine which use nozzle as officers the direction of a stream water in order to move around of blade turbine. The rotating of turbine blade efected by some parameters such as the distance of the nozzle, position of nozzle, diameter of nozzle, number of nozzle, and the geometry shape of the blade turbine. An experimental study to analyze the affect of distance and position nozzle to Pelton Turbine of performance. The research method used experiment parameter was position of nozzle with three variations, first position is the right side horizontal of bottom shaft turbine, second position is vertical to down direction, and third position is the left side horizontal of upper shaft turbine. The parameter of nozzle distance used five variations was 24 cm, 23 cm, 22 cm, 21 cm, dan 20 cm, which measured from the end of position nozzle to blade turbine. The result shows that the right side horizontal of bottom shaft turbine with distance of nozzle 23 cm had the maximum performance to produce a power 125 Watt with the rotation of shaft turbine 263 rpm.

  4. Determining the fracture resistance of fibre-reinforced glass matrix composites by means of the chevron-notch flexural technique

    Czech Academy of Sciences Publication Activity Database

    Boccaccini, A. R.; Kern, H.; Dlouhý, Ivo

    2001-01-01

    Roč. 308, 1/2 (2001), s. 111-117 ISSN 0921-5093 R&D Projects: GA ČR GV101/96/K264 Institutional research plan: CEZ:AV0Z2041904 Keywords : glass matrix composites * fracture toughness * chevron notch test Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.978, year: 2001

  5. Long-term Follow-up of a Randomized Controlled Trial Comparing Scarf to Chevron Osteotomy in Hallux Valgus Correction.

    Science.gov (United States)

    Jeuken, Ralph M; Schotanus, Martijn G M; Kort, Nanne P; Deenik, Axel; Jong, Bob; Hendrickx, Roel P M

    2016-07-01

    Hallux valgus is one of the most common foot deformities. This long-term follow-up study compared the results of 2 widely used operative treatments for hallux valgus: the scarf and chevron osteotomy. Conventional weight bearing anteroposterior (AP) radiographs of the foot were made for evaluating the intermetatarsal angle and hallux valgus angle. For clinical evaluation, the American Orthopaedic Foot & Ankle Society (AOFAS) rating system for the hallux metatarsophalangeal-interphalangeal scale was used together with physical examination of the foot. These data were compared with the results from the original study. The Short Form 36 questionnaire, the Manchester-Oxford Foot Questionnaire (MOXFQ), and a general questionnaire including a visual analog scale (VAS) pain score were used for subjective evaluation. The primary outcome measures were the radiologic recurrence of hallux valgus and reoperation rate of the same toe. Secondary outcome measures were the results from the radiographs and subjective and clinical evaluation. The response rate was 76% at the follow-up of 14 years; in the chevron group, 37 feet were included compared with 36 feet in the scarf group. Twenty-eight feet in the chevron group and 27 in the scarf group developed recurrence of hallux valgus (P = .483). One patient in the scarf group had a reoperation of the same toe compared with none in the chevron group (P = .314). Current VAS pain scores and results from the SF-36, MOXFQ, and AOFAS did not significantly differ between groups. Both techniques showed similar results after 2 years of follow-up. At 14 years of follow-up, neither technique was superior in preventing recurrence. Level II, randomized controlled trial. © The Author(s) 2016.

  6. Cavitation and multiphase flow forum - 1985

    International Nuclear Information System (INIS)

    Hoyt, J.W.; Furuya, O.

    1985-01-01

    This book presents the papers given at a conference on fluid flow. Topics considered at the conference included cavitation inception, bubble growth, cavitation noise, holography, axial flow pumps, vortices, cavitation erosion, two-phase flow in nozzles, coal slurry valves, hopper flows of granular materials, helium bubble transport in a closed vertical duct, and a numerical model for flow in a venturi scrubber

  7. Structural, electronic and magnetic properties of chevron-type graphene, BN and BC{sub 2}N nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, T.; Azevedo, S. [Departamento de Física/CCEN, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900 João Pessoa, PB (Brazil); Kaschny, J.R. [Instituto Federal da Bahia-Campus Vitória da Conquista, Caixa Postal 3150, 45075-265 Vitória da Conquista, BA (Brazil)

    2017-04-15

    Graphene nanoribbons are predicted to be essential components in future nanoelectronics. The size, edge type, arrangement of atoms and width of nanoribbons drastically change their properties. Boronnitrogencarbon nanoribbons properties are not fully understood so far. In the present contribution it was investigated the structural, electronic and magnetic properties of chevron-type carbon, boron nitride and BC{sub 2}N nanoribbons, using first-principles calculations. The results indicate that the structural stability is closely related to the discrepancies in the bond lengths, which can induce structural deformations and stress. Such nanoribbons present a wide range of electronic behaviors, depending on their composition and particularities of the atomic arrangement. A net magnetic moment is found for structures that present carbon atoms at the nanoribbon borders. Nevertheless, the calculated magnetic moment depends on the peculiarities of the symmetric arrangement of atoms and imbalance of carbon atoms between different sublattices. It was found that all structures which have a significant energy gap do not present magnetic moment, and vice-versa. Such result indicates the strong correlation between the electronic and magnetic properties of the chevron-type nanoribbons. - Highlights: • Small discrepancies between distinct bond lengths can influence the formation energy of the BC{sub 2}N nanoribbons. • The electronic behavior of the BC{sub 2}N chevron-type nanoribbons depends on the atomic arrangement and structural symmetries. • There is a strong correlation between the electronic and magnetic properties for the BC{sub 2}N structures.

  8. Experimental and numerical investigation of the cap-shock structure in over expanded thrust-optimized nozzles

    Energy Technology Data Exchange (ETDEWEB)

    Reijasse, P.; Bouvier, F.; Servel, P.

    2002-07-01

    This paper deals with the aerodynamics of an over-expanded nozzle, when the internal parabolic contour of the nozzle extension is highly thrust-optimized in terms of specific impulse-to-weight ratio. This optimization leads to an internal focusing shock issuing from a little downstream from the throat, even when the nozzle is running at nearly vacuum conditions. When such a nozzle is over-expanded, the focusing shock thus interferes with the over-expansion shock, and it forms from this shock interference a particular shock system, named 'cap-shock' because of the cap-like luminous shape seen in the over-expanded plumes of some real engines. Navier-Stokes calcinations performed in Europe had permitted to numerically analyze such a flow pattern, and they have revealed notably a recirculation bubble on the centerline downstream of the Mach disk, which had never been measured yet. A test campaign characterizing the flow separation in over-expanded sub-scale nozzles has been performed in the R2Ch blowdown wind tunnel of the Onera Chalais-Meudon center. Schlieren photographs of the exhaust jet have authorized a detailed description of the cap-shock pattern. Two-components Laser Doppler Velocimetry measurements have confirmed the existence of a recirculation bubble surrounded by an annular supersonic jet and has given its size. In addition to the calculations and the Schlieren interpretative sketches, these first quantitative experimental characterization of the cap-shock structure permit to state a physical description of the cap-shock induced flow field in the thrust-optimized nozzles. (authors)

  9. Development of top nozzle for Korean standard LWR fuel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S. K.; Kim, I. K.; Choi, K. S.; Kim, Y. H.; Lee, J. N.; Kim, H. K. [KNFC, Taejon (Korea, Republic of)

    2001-10-01

    Performance evaluation was executed for each component and its assembly for the deduced Top Nozzles to develop the new Top Nozzle for LWR. This new Top Nozzle is composed of the optimum components among the derived Top Nozzles that have been evaluated in the viewpoint of structural integrity, simpleness of dismantle and assembly, manufacturability etc. In this study, the developed Top Nozzle satisfied all the related design criteria. In special, it makes fuel repair time reduced by assembling and disassembling itself as one body, and improves Fuel Assembly holddown ability by revising the design parameters of its spring and the structural integrity through the betterment of its geometrical shpae of Flange and Holddown Plate as compared with the existing LWR Top Nozzles.

  10. Mounting apparatus for a nozzle guide vane assembly

    Science.gov (United States)

    Boyd, Gary L.; Shaffer, James E.

    1995-01-01

    The present invention provides a ceramic nozzle guide assembly with an apparatus for mounting it to a metal nozzle case that includes an intermediate ceramic mounting ring. The mounting ring includes a plurality of projections that are received within a plurality of receptacles formed in the nozzle case. The projections of the mounting ring are secured within the receptacles by a ceramic retainer that allows contact between the two components only along arcuate surfaces thus eliminating sliding contact between the components.

  11. Fluidized-bed calciner with combustion nozzle and shroud

    International Nuclear Information System (INIS)

    Wielang, J.A.; Palmer, W.B.; Kerr, W.B.

    1977-01-01

    A nozzle employed as a burner within a fluidized bed is coaxially enclosed within a tubular shroud that extends beyond the nozzle length into the fluidized bed. The open-ended shroud portion beyond the nozzle end provides an antechamber for mixture and combustion of atomized fuel with an oxygen-containing gas. The arrangement provides improved combustion efficiency and excludes bed particles from the high-velocity, high-temperature portions of the flame to reduce particle attrition. 4 claims, 2 figures

  12. Transient heating effects in high pressure Diesel injector nozzles

    International Nuclear Information System (INIS)

    Strotos, George; Koukouvinis, Phoevos; Theodorakakos, Andreas; Gavaises, Manolis; Bergeles, George

    2015-01-01

    Highlights: • Simulation of friction-induced heating in high pressure Diesel fuel injectors. • Injection pressures up to 3000 bar. • Simulations with variable fuel properties significantly affect predictions. • Needle motion affects flow and temperature fields. • Possible heterogeneous boiling as injection pressures increase above 2000 bar. - Abstract: The tendency of today’s fuel injection systems to reach injection pressures up to 3000 bar in order to meet forthcoming emission regulations may significantly increase liquid temperatures due to friction heating; this paper identifies numerically the importance of fuel pressurization, phase-change due to cavitation, wall heat transfer and needle valve motion on the fluid heating induced in high pressure Diesel fuel injectors. These parameters affect the nozzle discharge coefficient (C d ), fuel exit temperature, cavitation volume fraction and temperature distribution within the nozzle. Variable fuel properties, being a function of the local pressure and temperature are found necessary in order to simulate accurately the effects of depressurization and heating induced by friction forces. Comparison of CFD predictions against a 0-D thermodynamic model, indicates that although the mean exit temperature increase relative to the initial fuel temperature is proportional to (1 − C d 2 ) at fixed needle positions, it can significantly deviate from this value when the motion of the needle valve, controlling the opening and closing of the injection process, is taken into consideration. Increasing the inlet pressure from 2000 bar, which is the pressure utilized in today’s fuel systems to 3000 bar, results to significantly increased fluid temperatures above the boiling point of the Diesel fuel components and therefore regions of potential heterogeneous fuel boiling are identified

  13. Effect of carrier gas pressure on condensation in a supersonic nozzle

    International Nuclear Information System (INIS)

    Wyslouzil, B.E.; Wilemski, G.; Beals, M.G.; Frish, M.B.

    1994-01-01

    Supersonic nozzle experiments were performed with a fixed water or ethanol vapor pressure and varying amounts of nitrogen to test the hypothesis that carrier gas pressure affects the onset of condensation. Such an effect might occur if nonisothermal nucleation were important under conditions of excess carrier gas in the atmospheric pressure range, as has been suggested by Ford and Clement [J. Phys. A 22, 4007 (1989)]. Although a small increase was observed in the condensation onset temperature as the stagnation pressure was reduced from 3 to 0.5 atm, these changes cannot be attributed to any nonisothermal effects. The pulsed nozzle experiments also exhibited two interesting anomalies: (1) the density profiles for the water and ethanol mixtures were shifted in opposite directions from the dry N 2 profile; (2) a long transient period was required before the nozzle showed good pulse-to-pulse repeatability for condensible vapor mixtures. To theoretically simulate the observed onset behavior, calculations of nucleation and droplet growth in the nozzle were performed that took into account two principal effects of varying the carrier gas pressure: (1) the change in nozzle shape due to boundary layer effects and (2) the variation in the heat capacity of the flowing gas. Energy transfer limitations were neglected in calculating the nucleation rates. The trend of the calculated results matched that of the experimental results very well. Thus, heat capacity and boundary layer effects are sufficient to explain the experimental onset behavior without invoking energy transfer limited nucleation. The conclusions about the rate of nucleation are consistent with those obtained recently using an expansion cloud chamber, but are at odds with results from thermal diffusion cloud chamber measurements

  14. Method of fault diagnosis in nozzle cascades for U-235 enrichment

    International Nuclear Information System (INIS)

    Schuette, R.; Steinhaus, H.

    1978-09-01

    In a separation nozzle cascade for enrichment of the light uranium isotope U-235 some 450 stages are connected in series. For optimum separation performance of such a plant the design values of the nozzle inlet pressure, of the UF 6 concentration of the UF 6 -cut and the cut of the light additional gas must be matched in all separation stages. Also the feed stream, the product stream, and the tails stream have to be controlled according to the cascade design values. Since it is not possible to measure the cuts directly, these values are calculated on the basis of the material flow balances of the cascade using the pressure values and the UF 6 concentration measurements in each stage, these data being supplemented by concentration measurements in the light and heavy fractions of selected stages. This approach requires the use of a digital computer for processing some 1500 readings to calculate the 2500 plant parameters defining the plant state. This study describes a method of diagnosing the major faults to be expected in a separation nozzle cascade. It is based on the fact that the fault profiles are characterized sufficiently well by maximum values and values to identify the cause of a fault and localize the point where it occurs by means of simple relations between these six values and of their relative positions. The performance of the method has been tested in experiments in the ten-stage pilot plant. For use in commercial separation nozzle cascades the range of performance and the special mode of implementation can be derived from the characteristics of the plant components (separation nozzles, compressors, control valves). The methodological approach in this fault diagnosis also provides the basis for computer aided control procedures to raise a separation cascade from any steady plant condition to its set point operation. (orig./HP) 891 HP [de

  15. Transient Three-Dimensional Analysis of Nozzle Side Load in Regeneratively Cooled Engines

    Science.gov (United States)

    Wang, Ten-See

    2005-01-01

    Three-dimensional numerical investigations on the start-up side load physics for a regeneratively cooled, high-aspect-ratio nozzle were performed. The objectives of this study are to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and a transient inlet condition based on an engine system simulation. Computations were performed for both the adiabatic and cooled walls in order to understand the effect of boundary conditions. Finite-rate chemistry was used throughout the study so that combustion effect is always included. The results show that three types of shock evolution are responsible for side loads: generation of combustion wave; transitions among free-shock separation, restricted-shock separation, and simultaneous free-shock and restricted shock separations; along with oscillation of shocks across the lip. Wall boundary conditions drastically affect the computed side load physics: the adiabatic nozzle prefers free-shock separation while the cooled nozzle favors restricted-shock separation, resulting in higher peak side load for the cooled nozzle than that of the adiabatic nozzle. By comparing the computed physics with those of test observations, it is concluded that cooled wall is a more realistic boundary condition, and the oscillation of the restricted-shock separation flow pattern across the lip along with its associated tangential shock motion are the dominant side load physics for a regeneratively cooled, high aspect-ratio rocket engine.

  16. Analysis of the combined effect of hydrogrinding process and inclination angle on hydraulic performance of diesel injection nozzles

    International Nuclear Information System (INIS)

    Salvador, F.J.; Carreres, M.; Jaramillo, D.; Martínez-López, J.

    2015-01-01

    Highlights: • Effect of inclination angle and rounding radius of diesel nozzle holes is explored. • The study starts with experimental tests and is extended by CFD simulations. • A CFD code with a HEM model for two-phase flow and a RANS approach is used. • Differences in flow parameters, cavitation inception and morphology are analysed. • The flow is generally favoured by low inclination angles and high rounding radius. - Abstract: A computational study to investigate the influence of the orifices inclination and the rounding radius at the orifice inlet (consequence of the hydro-erosive grinding process applied after the orifices machining) over the internal nozzle flow is performed in this paper. The study starts with the analysis of experimental results where the mass flow and momentum flux of two nozzles with very different values of these two variables are compared. This analysis shows relatively small differences in terms of mass flow and momentum flux, since the higher losses associated to the higher deflection of the streamlines with a higher inclination of the orifices are counteracted by the higher rounding radius, which favours the flow entrance to the orifice. To explain this experimental outcome, an extensive computational study involving nine geometries that combine different inclination angles and rounding radius is conducted, in order to quantify the influence of both parameters on the flow separately, as well as to assess the potential of their combination. These geometries are compared in terms of discharge coefficient, critical cavitation conditions and effective injection velocity, among others. Results show differences up to 15% in terms of mass flow rate and 8% for the effective injection velocity among the two extreme cases (lowest inclination and highest hydro-erosion level versus the nozzle with the highest inclination and lowest hydro-erosion level). Given the importance of these phenomena on the subsequent mixing and combustion

  17. BWR feedwater nozzle and control-rod-drive return line nozzle cracking

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    In its 1978 Annual Report to Congress, the Nuclear Regulatory Commission identified as an unresolved safety issue the appearance of cracks in feedwater nozzles at boiling-water reactors (BWRs). Later similar cracking, detected in return water lines for control-rod-drive systems at BWRs, was designated Part II of the issue. This article outlines the resolution of these cracking problems

  18. Transient and steady-state flows in shock tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Hannemann, K. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Goettingen (Germany); Jacobs, P.A. [Queensland Univ., Brisbane (Australia). Dept. of Mechanical Engineering; Thomas, A.; McIntyre, T.J. [Queensland Univ., Brisbane, QLD. (Australia). Dept. of Physics

    1999-12-01

    Due to the difficulty of measuring all necessary flow quantities in the nozzle reservoir and the test section of high enthalpy shock tunnels, indirect computational methods are necessary to estimate the required flow parameters. In addition to steady state flow computations of the nozzle flow and the flow past wind tunnel models it is necessary to investigate the transient flow in the facility in order to achieve a better understanding of its performance. These transient effects include the nozzle starting flow, the interaction of the shock tube boundary layers and the reflected shock, thermal losses in the shock reflection region and the developing boundary layers in the expanding section of the nozzle. Additionally, the nonequilibrium chemical and thermal relaxation models which are used to compute high enthalpy flows have to be validated with appropriate experimental data. (orig.)

  19. Transient and steady-state flows in shock tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Hannemann, K. (Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Goettingen (Germany)); Jacobs, P.A. (Queensland Univ., Brisbane (Australia). Dept. of Mechanical Engineering); Thomas, A.; McIntyre, T.J. (Queensland Univ., Brisbane, QLD. (Australia). Dept. of Physics)

    1999-01-01

    Due to the difficulty of measuring all necessary flow quantities in the nozzle reservoir and the test section of high enthalpy shock tunnels, indirect computational methods are necessary to estimate the required flow parameters. In addition to steady state flow computations of the nozzle flow and the flow past wind tunnel models it is necessary to investigate the transient flow in the facility in order to achieve a better understanding of its performance. These transient effects include the nozzle starting flow, the interaction of the shock tube boundary layers and the reflected shock, thermal losses in the shock reflection region and the developing boundary layers in the expanding section of the nozzle. Additionally, the nonequilibrium chemical and thermal relaxation models which are used to compute high enthalpy flows have to be validated with appropriate experimental data. (orig.)

  20. Nozzle evaluation for Project W-314

    International Nuclear Information System (INIS)

    Galbraith, J.D.

    1998-01-01

    Revisions to the waste transfer system piping to be implemented by Project W-314 will eliminate the need to access a majority of interfarm jumper connections associated with specific process pits. Additionally, connections that formerly facilitated waste transfers from the Plutonium-Uranium Extraction (PUREX) Plant are no longer required. This document identified unneeded process pit jumper connections, describes former designated routing, denotes current status (i.e., open or blanked), and recommends appropriate disposition for all. Blanking of identified nozzles should be accomplished by Project W-314 upon installation of jumpers and acceptance by Tank Waste Remediation System (TWRS) Tank Farm Operations

  1. Gas flow in miniaturized nozzles for micro-thrusters

    NARCIS (Netherlands)

    La Torre, F.

    2011-01-01

    A new satellite philosophy, developed during the last two decades, suggests to make satellites smaller and lighter rather than bigger and heavier. In other words, large (?m3), single system satellites are being replaced by ?eets of small (?dm3), so-called micro-satellites. Future developmentsmay

  2. Study of Magnetogasdynamic Flow Acceleration in a Scramjet Nozzle

    National Research Council Canada - National Science Library

    Ross, Erik K

    2005-01-01

    .... Using an AFRL/VAAC CFD code that was modified for MGD computations, this project investigated the effect conductivity and load factor had on the specific thrust and efficiency of an MGD accelerator...

  3. Numerical analysis of choked converging nozzle flows with surface ...

    Indian Academy of Sciences (India)

    numerically investigated by means of a recent computational model that ..... dependent nonlinear formulations, where the solution scheme is most likely to face with .... boundary and geometric conditions, to (15–16), also proves the validity.

  4. Gas flow parameters in laser cutting of wood- nozzle design

    Science.gov (United States)

    Kali Mukherjee; Tom Grendzwell; Parwaiz A.A. Khan; Charles McMillin

    1990-01-01

    The Automated Lumber Processing System (ALPS) is an ongoing team research effort to optimize the yield of parts in a furniture rough mill. The process is designed to couple aspects of computer vision, computer optimization of yield, and laser cutting. This research is focused on optimizing laser wood cutting. Laser machining of lumber has the advantage over...

  5. Simulation model of converging-diverging (CD) nozzle to improve particle delivery system of deoxyribonucleic acid (DNA)

    Science.gov (United States)

    Sumarsono, Danardono A.; Ibrahim, Fera; Santoso, Satria P.; Sari, Gema P.

    2018-02-01

    Gene gun is a mechanical device which has been used to deliver DNA vaccine into the cells and tissues by increasing the uptake of DNA plasmid so it can generate a high immune response with less amount of DNA. Nozzle is an important part of the gene gun which used to accelerate DNA in particle form with a gas flow to reach adequate momentum to enter the epidermis of human skin and elicit immune response. We developed new designs of nozzle for gene gun to make DNA uptake more efficient in vaccination. We used Computational Fluid Dynamics (CFD) by Autodesk® Simulation 2015 to simulate static fluid pressure and velocity contour of supersonic wave and parametric distance to predict the accuracy of the new nozzle. The result showed that the nozzle could create a shockwave at the distance parametric to the object from 4 to 5 cm using fluid pressure varied between 0.8-1.2 MPa. This is indication a possibility that the DNA particle could penetrate under the mammalian skin. For the future research step, this new nozzle model could be considered for development the main component of the DNA delivery system in vaccination in vivo

  6. Toxicity of Chevron Escravos crude oil and chemical dispersant on guinea pig testicular function.

    Science.gov (United States)

    Afonne, Onyenmechi Johnson; Onyiaorah, Igwebuike Victor; Orisakwe, Orish Ebere

    2013-01-01

    Chemical contaminants have been found to affect reproductive functions in mammals. This study investigated the effect of Chevron Escravos crude oil and Emulsol L.W. dispersant on the testicular functions of guinea pig. Eight groups of seven sexually mature male guinea pigs each were given 1250, 2500, or 5000 mg/kg of crude oil and dispersant for 7 days. The fluid and food intake and body weight of the animals were measured daily throughout the study. After the exposure period, sperm quality analysis was carried out, and fructose and lactate dehydrogenase were analyzed in tissue homogenate, while testosterone and estradiol were assayed in blood. The right testis was also processed for histological analysis. The epididymal sperm number and fructose level of treated animals showed a significant dose-dependent decrease (pguinea pigs. The possible mechanism of toxicity is suggested to be by stimulation of hormone production from the adrenal cortex, causing a negative feedback on gonadotropin-releasing hormone in the pituitary gland to suppress spermatogenesis.

  7. Magnetoresistance and noise properties of chevron stretcher detectors for field access bubble domain devices

    Science.gov (United States)

    George, P. K.; Oeffinger, T. R.; Chen, T. T.

    1976-01-01

    Experiments were devised to study the angular variation of the resistance and noise properties of one- and two-level chevron stretcher magnetoresistive detectors for use in field access bubble memory devices. All measurements, made with an electronic system, were performed on glass or garnet samples upon which 1 micron of SiO2 was sputter-deposited, followed by 4000 A of Permalloy for the 28-micron-period devices and 0.8 microns of SiO2, followed by 3000 A of Permalloy for the 20-micron-period devices. The geometrical and drive-state dependence of the zero-state noise were studied, as was its frequency dependence. It is found that both types of detectors operate primarily in the amplitude-shift mode for drive fields of interest and that the presence of a bubble in a detector causes a magnetoresistance change equal to that produced by increasing the in-plane drive field about 8 Oe in the absence of a bubble.

  8. Analysis of plume backflow around a nozzle lip in a nuclear rocket

    International Nuclear Information System (INIS)

    Chung, C.H.; Kim, S.C.; Stubbs, R.M.; De Witt, K.J.

    1993-06-01

    The structure of the flow around a nuclear thermal rocket nozzle lip has been investigated using the direct simulation Monte Carlo method. Special attention has been paid to the behavior of a small amount of harmful particles that may be present in the rocket exhaust gas. The harmful fission product particles are modeled by four inert gases whose molecular weights are in a range of 4 131. Atomic hydrogen, which exists in the flow due to the extremely high nuclear fuel temperature in the reactor, is also included. It is shown that the plume backflow is primarily determined by the thin subsonic fluid layer adjacent to the surface of the nozzle lip, and that the inflow boundary in the plume region has negligible effect on the backflow. It is also shown that a relatively large amount of the lighter species is scattered into the backflow region while the amount of the heavier species becomes negligible in this region due to extreme separation between the species. Results indicate that the backscattered molecules are very energetic and are fast-moving along the surface in the backflow region near the nozzle lip. 22 refs

  9. Investigation of Direct-Injection via Micro-Porous Injector Nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Reijnders, J.J.E.; Boot, M.D.; Luijten, C.C.M.; De Goey, L.P.H.

    2009-02-15

    The possibility to reduce soot emissions by means of injecting diesel fuel through a porous injector is investigated. From literature it is known that better oxygen entrainment into the fuel spray leads to lower soot emissions. By selection of porous material properties and geometry, the spray is tunable such that a maximum of air, present in the cylinder, is utilized. A numerical model has been created to predict the flow through the porous nozzle. Experiments are reported on the spray shape, flow rate and the durability of the porous injector under atmospheric circumstances.

  10. Top Nozzle Holddown Spring Optimization of KSNP Fuel Assembly

    International Nuclear Information System (INIS)

    Lee, Seong Ki; Park, Nam Kyu; Kim, Hyeong Koo; Lee, Joon Ro; Kim, Jae Won

    2002-01-01

    Nuclear fuel assembly for Korea Standard Nuclear Power (KSNP) Plant has 4 helical compression springs at the upper end of it. The springs, in conjunction with the fuel assembly weight, apply a holddown force against excess of buoyancy forces and the upward hydraulic forces due to the reactor coolant flow. Thus the holddown spring is to be designed such that the positive net downward force will be maintained for all normal and anticipated transient flow and temperature conditions in the nuclear reactor. With satisfying these in-reactor requirements of the fuel assembly holddown spring. Under the assumption that spring density is constant, the volume nozzle holddown spring. Under the assumption that spring density is constant, the volume minimization is executed by using the design variables, viz., wire diameter, mean coil diameter, minimization is executed by using the design variables, viz., wire diameter, mean coil diameter are within the compatible range of the fuel assembly structural components. Based on these conditions, the optimum design of the holddown spring is obtained considering the reactor operating condition and by using ANSYS code. The optimized spring has the properties that are a decreased volume and increased stiffness, compared with the existing one even if the absolute values are very similar each other. The holddown spring design features and the algorithm developed in this study could be directly applicable to the current commercial production. Therefore, it could be used to enhance the design efficiency and the functional performance of the spring, and to reduce a material cost a little

  11. EURCYL. A program to generate finite element meshes for pressure vessel nozzles

    International Nuclear Information System (INIS)

    De Windt, P.; Reynen, J.

    1974-12-01

    EURCYL is a program dealing with the automatic generation of finite element meshes for pressure vessel nozzles, using isoparametric elements with 8, 20 or 32 nodes. Options exist to generate BWR nozzles as well as PWR nozzles

  12. Analysis of plasma behavior in a magnetic nozzle of laser fusion rocket

    International Nuclear Information System (INIS)

    Nagamine, Yoshihiko; Yoshimi, Naofumi; Nakama, Yuji; Muranaka, Takanobu; Mayumi, Takao; Nakashima, Hideki

    1997-01-01

    A magnetic nozzle concept in a laser fusion rocket is suitable for controlling the fusion plasma flow and it has an advantage that thermalization with wall structures in a thrust chamber can be avoided. Rayleigh-Taylor instability would occur at the surface of expanding plasma and it would lead to the degradation of thrust efficiency, due to diffusion of the plasma through ambient decelerating magnetic field. A 3D hybrid particle-in-cell code has been developed to analyze the plasma instability in the magnetic nozzle. The resultant linear growth rate γ of the instability is found to be 2.96 x 10 6 and it is in good agreement with the theoretical value from conventional Rayleigh Taylor instability. (author)

  13. An Automated DAKOTA and VULCAN-CFD Framework with Application to Supersonic Facility Nozzle Flowpath Optimization

    Science.gov (United States)

    Axdahl, Erik L.

    2015-01-01

    Removing human interaction from design processes by using automation may lead to gains in both productivity and design precision. This memorandum describes efforts to incorporate high fidelity numerical analysis tools into an automated framework and applying that framework to applications of practical interest. The purpose of this effort was to integrate VULCAN-CFD into an automated, DAKOTA-enabled framework with a proof-of-concept application being the optimization of supersonic test facility nozzles. It was shown that the optimization framework could be deployed on a high performance computing cluster with the flow of information handled effectively to guide the optimization process. Furthermore, the application of the framework to supersonic test facility nozzle flowpath design and optimization was demonstrated using multiple optimization algorithms.

  14. Influences of hydrodynamic conditions, nozzle geometry on appearance of high submerged cavitating jets

    Directory of Open Access Journals (Sweden)

    Hutli Ezddin

    2013-01-01

    Full Text Available Based on visualization results of highly-submerged cavitating water jet obtained with digital camera, the influences of related parameters such as: injection pressure, nozzle diameter and geometry, nozzle mounting (for convergent / divergent flow, cavitation number and exit jet velocity, were investigated. In addition, the influence of visualization system position was also studied. All the parameters have been found to be of strong influence on the jet appearance and performance. Both hydro-dynamical and geometrical parameters are playing the main role in behavior and intensity of cavitation phenomenon produced by cavitating jet generator. Based on our considerable previous experience in working with cavitating jet generator, the working conditions were chosen in order to obtain measurable phenomenon. [Projekat Ministarstva nauke Republike Srbije, br. TR35046

  15. Transient two-phase flow

    International Nuclear Information System (INIS)

    Hsu, Y.Y.

    1974-01-01

    The following papers related to two-phase flow are summarized: current assumptions made in two-phase flow modeling; two-phase unsteady blowdown from pipes, flow pattern in Laval nozzle and two-phase flow dynamics; dependence of radial heat and momentum diffusion; transient behavior of the liquid film around the expanding gas slug in a vertical tube; flooding phenomena in BWR fuel bundles; and transient effects in bubble two-phase flow. (U.S.)

  16. Nucleation of super-critical carbon dioxide in a venturi nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Jarrahbashi, D., E-mail: dorrin.jarrahbashi@me.gatech.edu; Pidaparti, S.R.; Ranjan, D.

    2016-12-15

    Highlights: • Nucleation of S-CO{sub 2} in a nozzle near critical point has been computationally studied. • The nucleation behavior is very sensitive to the inlet pressure and temperature. • After nucleation, high liquid-content two-phase mixture near wall travels downstream. - Abstract: Pressure reduction at the entrance of the compressor in supercritical CO{sub 2} Brayton cycles may cause nucleation and create a mixture of vapor and liquid droplets due to operation near the saturation conditions. Transient behavior of the flow after nucleation may cause serious issues in operation of the cycle and degrade the materials used in the design. The nucleation behavior of supercritical carbon-dioxide inside a venturi nozzle near the critical point is computationally studied. A transient compressible 3D Navier–Stokes solver, coupled with continuity, and energy equations have been implemented. In order to expedite the simulations, Fluid property Interpolation Tables (FIT) based on a piecewise biquintic spline interpolation of Helmholtz energy have been integrated with OpenFOAM to model S-CO{sub 2} properties. The mass fraction of vapor created in the venturi nozzle has been calculated using homogeneous equilibrium model (HEM). Nucleation behavior has been shown to be very sensitive to the inlet pressure, inlet temperature, and flow rate. The flow conditions that led to nucleation were identified. Nucleation was observed in the throat area and divergent section of the nozzle for mass flow rates from 0.050 kg/s to 0.065 kg/s, inlet pressure from 7.8 to 7.4 MPa for fixed exit pressure equal to 7.28 MPa. The inception of high-vapor-content nucleation was first observed in the throat area away from the side walls that remained confined to the throat region in later times. However, near the walls, a high liquid-content two-phase region was detected, first in the divergent section. At later times, the two-phase region was convected downstream toward the nozzle exit

  17. MASH full-scale crash testing of 4-ft mounting height, 24"\\0xD730" Chevron sign installed on 5.5H:1V slope ditch.

    Science.gov (United States)

    2013-03-01

    Current TxDOT practice allows installation of all existing chevron sizes on 7-ft mounting height, but restricts the use of 4-ft mounting height for the three smallest existing chevron signsthat is, 12 inches 18 inches, 18 inches 24 inches, a...

  18. Numerical study of saturation steam/water mixture flow and flashing initial sub-cooled water flow inside throttling devices

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    In this work, a Computational Fluid-Dynamics (CFD) approach to model this phenomenon inside throttling devices is proposed. To validate CFD results, different nozzle geometries are analyzed, comparing numerical results with experimental data. Two cases are studied: Case 1: saturation steam/water mixture flow inside 2D convergent-divergent nozzle (inlet, outlet and throat diameter of nozzle are 0.1213m, 0.0452m and 0.0191m respectively). In this benchmark, a range of total inle...

  19. Grit blasting nozzle fabricated from mild tool steel proves satisfactory

    Science.gov (United States)

    Mc Farland, J. E.; Turbitt, B.

    1966-01-01

    Dry blasting with glass beads through a nozzle assembly descales both the outside and inside surfaces of tubes of Inconel 718 used for the distribution of gaseous oxygen. The inside of the nozzle is coated with polyurethane and the deflector with a commercially available liquid urethane rubber.

  20. Multi-orifice deposition nozzle for additive manufacturing

    Science.gov (United States)

    Lind, Randall F.; Post, Brian K.; Cini, Colin L.

    2017-11-21

    An additive manufacturing extrusion head includes a nozzle for accepting and depositing a heated material onto a work surface and/or part. The nozzle includes a valve body and an internal poppet body moveable between positions to permit deposition of at least two bead sizes of heated material onto a work surface and/or part.

  1. Noise from Aft Deck Exhaust Nozzles: Differences in Experimental Embodiments

    Science.gov (United States)

    Bridges, James E.

    2014-01-01

    Two embodiments of a rectangular nozzle on an aft deck are compared. In one embodiment the lower lip of the nozzle was extended with the sidewalls becoming triangles. In a second embodiment a rectangular nozzle was fitted with a surface that fit flush to the lower lip and extended outward from the sides of the nozzle, approximating a semi-infinite plane. For the purpose of scale-model testing, making the aft deck an integral part of the nozzle is possible for relatively short deck lengths, but a separate plate model is more flexible, accounts for the expanse of deck to the sides of the nozzle, and allows the nozzle to stand off from the deck. Both embodiments were tested and acoustic far-field results were compared. In both embodiments the extended deck introduces a new noise source, but the amplitude of the new source was dependent upon the span (cross-stream dimension) of the aft deck. The noise increased with deck length (streamwise dimension), and in the case of the beveled nozzle it increased with increasing aspect ratio. In previous studies of slot jets in wings it was noted that the increased noise from the extended aft deck appears as a dipole at the aft deck trailing edge, an acoustic source type with different dependence on velocity than jet mixing noise. The extraneous noise produced by the aft deck in the present studies also shows this behavior both in directivity and in velocity scaling.

  2. Combustor nozzle for a fuel-flexible combustion system

    Science.gov (United States)

    Haynes, Joel Meier [Niskayuna, NY; Mosbacher, David Matthew [Cohoes, NY; Janssen, Jonathan Sebastian [Troy, NY; Iyer, Venkatraman Ananthakrishnan [Mason, OH

    2011-03-22

    A combustor nozzle is provided. The combustor nozzle includes a first fuel system configured to introduce a syngas fuel into a combustion chamber to enable lean premixed combustion within the combustion chamber and a second fuel system configured to introduce the syngas fuel, or a hydrocarbon fuel, or diluents, or combinations thereof into the combustion chamber to enable diffusion combustion within the combustion chamber.

  3. Ultrasonic pattern recognition study of feedwater nozzle inner radius indication

    International Nuclear Information System (INIS)

    Yoneyama, H.; Takama, S.; Kishigami, M.; Sasahara, T.; Ando, H.

    1983-01-01

    A study was made to distinguish defects on feed-water nozzle inner radius from noise echo caused by stainless steel cladding by using ultrasonic pattern recognition method with frequency analysis technique. Experiment has been successfully performed on flat clad plates and nozzle mock-up containing fatigue cracks and the following results which shows the high capability of frequency analysis technique are obtained

  4. Finite element analysis of inclined nozzle-plate junctions

    International Nuclear Information System (INIS)

    Dixit, K.B.; Seth, V.K.; Krishnan, A.; Ramamurthy, T.S.; Dattaguru, B.; Rao, A.K.

    1979-01-01

    Estimation of stress concentration at nozzle to plate or shell junctions is a significant problem in the stress analysis of nuclear reactors. The topic is a subject matter of extensive investigations and earlier considerable success has been reported on analysis for the cases when the nozzle is perpendicular to the plate or is radial to the shell. Analytical methods for the estimation of stress concentrations for the practical situations when the intersecting nozzle is inclined to the plate or is non-radial to the shell is rather scanty. Specific complications arise in dealing with the junction region when the nozzle with circular cross-section meets the non-circular cut-out on the plate or shell. In this paper a finite element analysis is developed for inclined nozzles and results are presented for nozzle-plate junctions. A method of analysis is developed with a view to achieving simultaneously accuracy of results and simplicity in the choice of elements and their connectivity. The circular nozzle is treated by axisymmetric conical shell elements. The nozzle portion in the region around the junction and the flat plate is dealt with by triangular flat shell elements. Special transition elements are developed for joining the flat shell elements with the axisymmetric elements under non-axisymmetric loading. A substructure method of analysis is adopted which achieves considerable economy in handling the structure and also conveniently combines the different types of elements in the structure. (orig.)

  5. TMI-2 instrument nozzle examinations at Argonne National Laboratory

    International Nuclear Information System (INIS)

    Neimark, L.A.; Shearer, T.L.; Purohit, A.; Hins, A.G.

    1993-09-01

    Six of the 14 instrument-penetration-tube nozzles removed from the lower head of TMI-2 were examined to identify damage mechanisms, provide insight to the fuel relocation scenario, and provide input data to the margin-to-failure analysis. Visual inspection, gamma scanning, metallography, microhardness measurements, and scanning electron microscopy were used to obtain the desired information. The results showed varying degrees of damage to the lower head nozzles, from ∼50% melt-off to no damage at all to near-neighbor nozzles. The elevations of nozzle damage suggested that the lower elevations (near the lower head) were protected from molten fuel, apparently by an insulating layer of fuel debris. The pattern of nozzle damage was consistent with fuel movement toward the hot-spot location identified in the vessel wall. Evidence was found for the existence of a significant quantity of control assembly debris on the lower head before the massive relocation of fuel occurred

  6. Analisa Laju Kegagalan Recloser untuk Mengurangi Kerugian Akibat Tidak Tersedianya Cadangan Recloser di PT. Chevron Pacific Indonesia - Riau

    OpenAIRE

    Khairul, Ahmad '; ', Nurhalim '

    2016-01-01

    In PT. Chevron Pacific Indonesia (PT. CPI), recloser is an important equipment for electric power systems that supposedly able to work optimally in a variety conditions probably happens on the systems. One of the causes of the losses incurred in PT.CPI is because of the recloser failure. Recloser failure is indeed a normal thing to happen, but the problem is when there is a failure (permanent damage) to the recloser which means that they must do the replacement, there is no backup available. ...

  7. Bunion correction using proximal chevron osteotomy: a single-incision technique.

    Science.gov (United States)

    Sammarco, G J; Russo-Alesi, F G

    1998-07-01

    Proximal chevron first metatarsal osteotomy with lateral capsulotomy, adductor tenotomy, and binding of the first and second metatarsals was reviewed in 88 consecutive cases. Seventy-two cases in 55 patients are reported, with an average clinical follow-up of 41 months. The hallux valgus angle improved an average of 15 degrees , from 32.0 degrees preoperatively to an average of 17.0 degrees postoperatively. The intermetatarsal I-II angle improved an average of 5.5 degrees, from 15.3 degrees preoperatively to 9.0 degrees postoperatively. The lateral plantar first metatarsal angle did not change. First metatarsal length was decreased by 2.0 mm. Union occurred at an average of 2 months. Sesamoid position improved 49%, from a preoperative average subluxation of 80% to a postoperative average subluxation of 29%. Subjective foot score profiles improved from a preoperative average of 70.1/100 to a postoperative average of 94.4/100 with respect to pain, deformity, motion, disability, and cosmesis. There were 10 patients with complications, including three patients with delayed unions, two with second metatarsal stress fractures, one with hallux varus, two with hallux limitus, one with progressive arthritis, one with cellulitis, and one with hallux elevatus. Eighty-four percent of the patients stated that they would undergo the procedure again without reservation, 9% would proceed with reservation, and 7% would not proceed with surgery again if offered. This technique provides reliable successful long-term results for the treatment of moderate and severe symptomatic bunion, hallux valgus, and metatarsus primus varus.

  8. Hallux Valgus Correction Comparing Percutaneous Chevron/Akin (PECA) and Open Scarf/Akin Osteotomies.

    Science.gov (United States)

    Lee, Moses; Walsh, James; Smith, Margaret M; Ling, Jeff; Wines, Andrew; Lam, Peter

    2017-08-01

    Minimally invasive surgery is being used increasingly, including for hallux valgus surgery. Despite the growing interest in minimally invasive procedures, there have been few publications on percutaneous chevron/akin (PECA) procedures, and no studies have been published comparing PECA to open scarf/akin osteotomies (SA). This was a prospective, randomized study of 50 patients undergoing operative correction of hallux valgus using one of 2 techniques (PECA vs open SA). Data were collected preoperatively and on 1 day, 2 weeks, 6 weeks, and 6 months postoperatively. Outcome measures include the American Orthopaedic Foot & Ankle Society Hallux-Metatarsophalangeal-Interphalangeal (AOFAS-HMI) Score, visual analog pain score, hallux valgus angle (HVA), and 1-2 intermetatarsal angle (IMA). Twenty-five patients underwent PECA procedures and 25 patients received SA procedures. Both groups showed significantly improved AOFAS-HMI scores after surgery (PECA group: 61.8 to 88.9, SA group: 57.3 to 84.1, P = .560) with comparable final scores. HVA and IMA also presented similar outcomes at final follow-up ( P = .520 and P = .270, respectively). However, the PECA group showed significantly lower pain level (VAS) in the early postoperative phase (postoperative day 1 to postoperative week 6, P < .001 and P = .004, respectively). No serious complications were observed in either group. Both groups showed comparable good to excellent clinical and radiologic outcomes at final follow-up. However, the PECA group had significantly less pain in the first 6 weeks following surgery. Level of Evidence Level II, prospective comparative study.

  9. A Basic Study on the Ejection of ICI Nozzle under Severe Accidents

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jong Rae; Bae, Ji Hoon; Bang, Kwang Hyun [Korea Maritime and Ocean University, Busan (Korea, Republic of); Park, Jong Woong [Dongguk University, Gyeongju (Korea, Republic of)

    2016-05-15

    Nozzle injection should be blocked because it affect to the environment if its melting core exposes outside. The purpose of this study is to carry out the thermos mechanical analysis due to debris relocation under severe accidents and to predict the nozzle ejection calculated considering the contact between the nozzle and lower head, and the supports of pipe cables. As a result of analyzing process of severe accidents, there was melting reaction between nozzle and the lower head. In this situation, we might predict the non-uniform contact region of nozzle hole of lower head and nozzle outside, delaying ejection of nozzles. But after melting, the average remaining length of the nozzle was 120mm and the maximum vertical displacement of lower nozzle near the weld is 3.3mm so there would be no nozzle this model, because the cable supports restrains the vertical displacement of nozzle.

  10. PULSED MOLECULAR BEAM PRODUCTION WITH NOZZLES

    Energy Technology Data Exchange (ETDEWEB)

    Hagena, Otto-Friedrich

    1963-05-15

    Molecular beam experiments that can be carried out in pulsed operation may be performed at considerably reduced expense for apparatus if, for pulse generation, the gas supply to the beam production system is interrupted as opposed to the usual steady molecular beam. This technique is studied by measuring intensity vs time of molecular beam impulses of varying length, how fast and through which intermediate states the initial intensity of the impulse attains equilibrium, and in which way the intensity of the molecular-beam impulse is affected by the pulse length and by increasing pressure in the first pressure stage. For production of pulses, a magnetically actuated, quick shutting, valve is used whose scaling area is the inlet cone of the nozzle used for the beam generation. The shortest pulses produced had a pulse length of 1.6 ms. (auth)

  11. Specific decontamination methods: water nozzle, cavitation erosion

    International Nuclear Information System (INIS)

    Boulitrop, D.; Gauchon, J.P.; Lecoffre, Y.

    1984-05-01

    The erosion and decontamination tests carried out in the framework of this study, allowed to specify the fields favourable to the use of the high pressure jet taking into account the determinant parameters that are the pressure and the target-nozzle distance. The previous spraying of gels with chemical reagents (sulfuric acid anf hydrazine) allows to get better decontamination factors. Then, the feasibility study of a decontamination method by cavitation erosion is presented. Gelled compounds for decontamination have been developed; their decontamination quality has been evaluated by comparative contamination tests in laboratory and decontamination tests of samples of materials used in nuclear industry; this last method is adapted to remote handling devices and produces a low quantity of secondary effluents, so it allows to clean high contaminated installation on the site without additional exposure of the personnel [fr

  12. Noise Prediction Module for Offset Stream Nozzles

    Science.gov (United States)

    Henderson, Brenda S.

    2011-01-01

    A Modern Design of Experiments (MDOE) analysis of data acquired for an offset stream technology was presented. The data acquisition and concept development were funded under a Supersonics NRA NNX07AC62A awarded to Dimitri Papamoschou at University of California, Irvine. The technology involved the introduction of airfoils in the fan stream of a bypass ratio (BPR) two nozzle system operated at transonic exhaust speeds. The vanes deflected the fan stream relative to the core stream and resulted in reduced sideline noise for polar angles in the peak jet noise direction. Noise prediction models were developed for a range of vane configurations. The models interface with an existing ANOPP module and can be used or future system level studies.

  13. Optimizing parameters of GTU cycle and design values of air-gas channel in a gas turbine with cooled nozzle and rotor blades

    Science.gov (United States)

    Kler, A. M.; Zakharov, Yu. B.

    2012-09-01

    The authors have formulated the problem of joint optimization of pressure and temperature of combustion products before gas turbine, profiles of nozzle and rotor blades of gas turbine, and cooling air flow rates through nozzle and rotor blades. The article offers an original approach to optimization of profiles of gas turbine blades where the optimized profiles are presented as linear combinations of preliminarily formed basic profiles. The given examples relate to optimization of the gas turbine unit on the criterion of power efficiency at preliminary heat removal from air flows supplied for the air-gas channel cooling and without such removal.

  14. Fluiddynamic effects in the fuel element top nozzle area during refilling and reflooding

    International Nuclear Information System (INIS)

    Hawighorst, A.; Kroening, H.; Mewes, D.; Spatz, R.; Mayinger, F.

    1985-01-01

    During the refilling and reflooding phase following a hypothetical loss of coolant accident in lightwater cooled nuclear reactors, there will be countercurrent flow between discharging steam and the feed of emergency core cooling water. It was the objective of this research project to contribute to a better physical understanding of the fluiddynamic processes in the area of the fuel element top nozzle and so to improve emergency core cooling calculations. Therefore, experimental and theoretical investigations about the entrainment and countercurrent behaviour of gas/liquid flows have been implemented within this project. Fluiddynamic processes in the fuel element top nozzle area were simulated during the reflooding and refilling phase. Based on special internals as single and multiple-hole orifices, basic phenomena of fluidynamics were studied first with air-water. Subsequently, investigations of the system steam/water were conducted. The reactor geometry was approximated step by step, until a complete reactor fuel assembly top nozzle was constituted. The system pressure was 4.8 bars (abs), in accordance with the conditions in the reactor pressure vessel at the end of the blowdown phase. The water was initially fed in at saturation temperature, then, as a second step, fed in at subcooled condition relative to the steam temperature, in order to be able to study condensation effects as well. First, investigations on gas/liquid countercurrent flows in the fluid system air/water are presented. Then one studies countercurrent flow in the system steam/water, including the investigation of condensation effects. Finally, a detailed description of the research on droplet size determination is given

  15. Design of Single Stage Axial Turbine with Constant Nozzle Angle Blading for Small Turbojet

    Science.gov (United States)

    Putra Adnan, F.; Hartono, Firman

    2018-04-01

    In this paper, an aerodynamic design of a single stage gas generator axial turbine for small turbojet engine is explained. As per design requirement, the turbine should be able to deliver power output of 155 kW at 0.8139 kg/s gas mass flow, inlet total temperature of 1200 K and inlet total pressure of 335330 Pa. The design phase consist of several steps, i.e.: determination of velocity triangles in 2D plane, 2D blading design and 3D flow analysis at design point using Computational Fluid Dynamics method. In the determination of velocity triangles, two conditions are applied: zero inlet swirl (i.e. the gas flow enter the turbine at axial direction) and constant nozzle angle design (i.e. the inlet and outlet angle of the nozzle blade are constant from root to tip). The 2D approach in cascade plane is used to specify airfoil type at root, mean and tip of the blade based on inlet and outlet flow conditions. The 3D approach is done by simulating the turbine in full configuration to evaluate the overall performance of the turbine. The observed parameters including axial gap, stagger angle, and tip clearance affect its output power. Based on analysis results, axial gap and stagger angle are positively correlated with output power up to a certain point at which the power decreases. Tip clearance, however, gives inversely correlation with output power.

  16. Mathematical Investigation of the Cavitation Phenomenon in the Nozzle with Partially Surface Wetting

    Directory of Open Access Journals (Sweden)

    Jablonská Jana

    2015-12-01

    Full Text Available Partially surface wetting has a great influence on friction losses in the fluid flow in both the pipeline system and the complex shape of hydraulic elements. In many hydraulic elements (valves, pump impellers, cavitation is generated, which significantly changes the hydraulic flow parameters, so the last part of the article is devoted to the mathematical solution of this phenomena and evaluates the impact of wall wetting on the size and shape of the cavitation area which appears in the nozzle and in small gaps at special conditions. If the cavitation appears e. g. near the wall of pipes, the blades of turbine or a pump, then it destroys the material surface. On the basis of this physical experiment (nozzle, a two-dimensional (2D mathematical cavitation model of Schnerr-Sauer was made and calculated shape and size of the cavitation region was compared with the experiment. Later this verified model of cavitation was used for cavitation research flow with partial surface wetting. The pressure drop and the size of the cavitation area as it flows from partially surface wetting theory was tested depending on the adhesion coefficient.

  17. Development of acoustically lined ejector technology for multitube jet noise suppressor nozzles by model and engine tests over a wide range of jet pressure ratios and temperatures

    Science.gov (United States)

    Atvars, J.; Paynter, G. C.; Walker, D. Q.; Wintermeyer, C. F.

    1974-01-01

    An experimental program comprising model nozzle and full-scale engine tests was undertaken to acquire parametric data for acoustically lined ejectors applied to primary jet noise suppression. Ejector lining design technology and acoustical scaling of lined ejector configurations were the major objectives. Ground static tests were run with a J-75 turbojet engine fitted with a 37-tube, area ratio 3.3 suppressor nozzle and two lengths of ejector shroud (L/D = 1 and 2). Seven ejector lining configurations were tested over the engine pressure ratio range of 1.40 to 2.40 with corresponding jet velocities between 305 and 610 M/sec. One-fourth scale model nozzles were tested over a pressure ratio range of 1.40 to 4.0 with jet total temperatures between ambient and 1088 K. Scaling of multielement nozzle ejector configurations was also studied using a single element of the nozzle array with identical ejector lengths and lining materials. Acoustic far field and near field data together with nozzle thrust performance and jet aerodynamic flow profiles are presented.

  18. Rebuilding of Rothe's nozzle measurements with OpenFOAM software

    International Nuclear Information System (INIS)

    Arlemark, Erik; Nedea, Silvia; Markelov, Gennady

    2012-01-01

    In this paper the dsmcFoam solver is tested and validated for the the three main solver functionalities of 1) free-stream boundary conditions, 2) kinetic intermolecular collision including internal degrees of freedom and 3) gas/surface interactions. The free-stream utility was improved such that a spatially uniform field of particles gets inserted now yielding reliable results for the cells located close to these patches. Implementation of the collision models were validated for two test cases (monatomic gas mixtures and diatomic gas) by observing the equilibration of both the kinetic and internal energies. It was found that the present code had good agreement to the independent codes of HAWK and SMILE as well as to results by G. Bird. The validation of the present codes treatment for the gas/surface interactions was evaluated using the benchmark case of Rothe's nozzle measurements. Results show that the present version of dsmcFoam obtained good agreements for this case compared to the measurements of Rothe for density and temperature. It was also found that the Navier-Stokes solver of OpenFOAM produced reasonable results, even though the local Knudsen number of the flow exceeds the range of applicability for this method, Kn=0.1.

  19. Application of LBB to a nozzle-pipe interface

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Y.J.; Sohn, G.H.; Kim, Y.J. [and others

    1997-04-01

    Typical LBB (Leak-Before-Break) analysis is performed for the highest stress location for each different type of material in the high energy pipe line. In most cases, the highest stress occurs at the nozzle and pipe interface location at the terminal end. The standard finite element analysis approach to calculate J-Integral values at the crack tip utilizes symmetry conditions when modeling near the nozzle as well as away from the nozzle region to minimize the model size and simplify the calculation of J-integral values at the crack tip. A factor of two is typically applied to the J-integral value to account for symmetric conditions. This simplified analysis can lead to conservative results especially for small diameter pipes where the asymmetry of the nozzle-pipe interface is ignored. The stiffness of the residual piping system and non-symmetries of geometry along with different material for the nozzle, safe end and pipe are usually omitted in current LBB methodology. In this paper, the effects of non-symmetries due to geometry and material at the pipe-nozzle interface are presented. Various LBB analyses are performed for a small diameter piping system to evaluate the effect a nozzle has on the J-integral calculation, crack opening area and crack stability. In addition, material differences between the nozzle and pipe are evaluated. Comparison is made between a pipe model and a nozzle-pipe interface model, and a LBB PED (Piping Evaluation Diagram) curve is developed to summarize the results for use by piping designers.

  20. Optimum geometry for boiler soot blowers nozzles; Geometria optima de toberas para deshollinadores de caldera

    Energy Technology Data Exchange (ETDEWEB)

    Espinoza Garza, Jesus; Garcia Tinoco, Guillermo J; Martinez Flores, Jose Oscar [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1990-12-31

    For boiler soot blowing converging-diverging nozzles are employed, whose function is to convert thermal energy of a gas into kinetic energy to remove the deposits that adhere to the heat exchanger surfaces. In this paper are described the experimental equipment and the methods for flow, dynamic pressure, discharge velocity and air expansion factor calculation in each nozzle, as a function of its design geometry, utilizing air from a five stage centrifugal compressor. The graphic analysis of the results, concludes that the most efficient nozzles are not the ones than develop the greatest velocity, but the ones of highest dynamic pressure at the outlet. The nozzle geometry that allows obtaining the maximum dynamic air pressure at the discharge is A{sub 2}/A{sub g}=1.3676 [Espanol] Para el deshollinado de calderas se utilizan las toberas convergentes-divergentes, cuya funcion es convertir la energia termica de un gas en energia cinetica para remover los depositos que se adhieren a las superficies de intercambio de calor. En este trabajo se describen el equipo experimental y los metodos de calculo para flujo, presion dinamica, velocidad a la descarga y factor de expansion del aire en cada tobera, como funcion de su geometria de diseno. Durante la experimentacion se evaluaron siete disenos diferentes de toberas, empleando aire de un compresor centrifugo de cinco etapas. Del analisis grafico de los resultados, se concluye que las toberas mas eficientes no son las que desarrollan mayor velocidad sino las de mayor presion dinamica de la salida. La geometria de tobera que permite obtener la maxima presion dinamica del aire a la descarga es A{sub 2}/A{sub g} = 1.3676.

  1. Optimum geometry for boiler soot blowers nozzles; Geometria optima de toberas para deshollinadores de caldera

    Energy Technology Data Exchange (ETDEWEB)

    Espinoza Garza, Jesus; Garcia Tinoco, Guillermo J.; Martinez Flores, Jose Oscar [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1989-12-31

    For boiler soot blowing converging-diverging nozzles are employed, whose function is to convert thermal energy of a gas into kinetic energy to remove the deposits that adhere to the heat exchanger surfaces. In this paper are described the experimental equipment and the methods for flow, dynamic pressure, discharge velocity and air expansion factor calculation in each nozzle, as a function of its design geometry, utilizing air from a five stage centrifugal compressor. The graphic analysis of the results, concludes that the most efficient nozzles are not the ones than develop the greatest velocity, but the ones of highest dynamic pressure at the outlet. The nozzle geometry that allows obtaining the maximum dynamic air pressure at the discharge is A{sub 2}/A{sub g}=1.3676 [Espanol] Para el deshollinado de calderas se utilizan las toberas convergentes-divergentes, cuya funcion es convertir la energia termica de un gas en energia cinetica para remover los depositos que se adhieren a las superficies de intercambio de calor. En este trabajo se describen el equipo experimental y los metodos de calculo para flujo, presion dinamica, velocidad a la descarga y factor de expansion del aire en cada tobera, como funcion de su geometria de diseno. Durante la experimentacion se evaluaron siete disenos diferentes de toberas, empleando aire de un compresor centrifugo de cinco etapas. Del analisis grafico de los resultados, se concluye que las toberas mas eficientes no son las que desarrollan mayor velocidad sino las de mayor presion dinamica de la salida. La geometria de tobera que permite obtener la maxima presion dinamica del aire a la descarga es A{sub 2}/A{sub g} = 1.3676.

  2. Fuel injector nozzle for an internal combustion engine

    Science.gov (United States)

    Cavanagh, Mark S.; Urven, Jr., Roger L.; Lawrence, Keith E.

    2008-11-04

    A direct injection fuel injector includes a nozzle tip having a plurality of passages allowing fluid communication between an inner nozzle tip surface portion and an outer nozzle tip surface portion and directly into a combustion chamber of an internal combustion engine. A first group of the passages have inner surface apertures located substantially in a first common plane. A second group of the passages have inner surface apertures located substantially in at least a second common plane substantially parallel to the first common plane. The second group has more passages than the first group.

  3. The fabrication of nozzles for nuclear components by welding

    International Nuclear Information System (INIS)

    Moraes, M.M.; Krausser, P.; Echeverria, J.A.V.

    1986-01-01

    A nozzle with medium outside diameter of 1000 mm and medium thickness of 150 mm composed integrally by deposited metal by submerged-arc (wire S3NiMo1, 0.5mm) was fabricated in NUCLEP. The nondestructive, mechanical, metallographic and chemical testing carried out in a test sample made by the same procedure and welding parameters, showed results according to specifications established for primary components for nuclear power plants, and the tests presented mechanical properties and tenacity better than similar nozzle samples. This nozzle is cheapest concerning to importations, in respecting to its forged similar. (M.C.K.) [pt

  4. The Effect of Bypass Nozzle Exit Area on Fan Aerodynamic Performance and Noise in a Model Turbofan Simulator

    Science.gov (United States)

    Hughes, Christopher E.; Podboy, Gary, G.; Woodward, Richard P.; Jeracki, Robert, J.

    2013-01-01

    The design of effective new technologies to reduce aircraft propulsion noise is dependent on identifying and understanding the noise sources and noise generation mechanisms in the modern turbofan engine, as well as determining their contribution to the overall aircraft noise signature. Therefore, a comprehensive aeroacoustic wind tunnel test program was conducted called the Fan Broadband Source Diagnostic Test as part of the NASA Quiet Aircraft Technology program. The test was performed in the anechoic NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel using a 1/5 scale model turbofan simulator which represented a current generation, medium pressure ratio, high bypass turbofan aircraft engine. The investigation focused on simulating in model scale only the bypass section of the turbofan engine. The test objectives were to: identify the noise sources within the model and determine their noise level; investigate several component design technologies by determining their impact on the aerodynamic and acoustic performance of the fan stage; and conduct detailed flow diagnostics within the fan flow field to characterize the physics of the noise generation mechanisms in a turbofan model. This report discusses results obtained for one aspect of the Source Diagnostic Test that investigated the effect of the bypass or fan nozzle exit area on the bypass stage aerodynamic performance, specifically the fan and outlet guide vanes or stators, as well as the farfield acoustic noise level. The aerodynamic performance, farfield acoustics, and Laser Doppler Velocimeter flow diagnostic results are presented for the fan and four different fixed-area bypass nozzle configurations. The nozzles simulated fixed engine operating lines and encompassed the fan stage operating envelope from near stall to cruise. One nozzle was selected as a baseline reference, representing the nozzle area which would achieve the design point operating conditions and fan stage performance. The total area change from

  5. Axial loading screw fixation for chevron type osteotomies of the distal first metatarsal: a retrospective outcomes analysis.

    Science.gov (United States)

    Murphy, Ryan M; Fallat, Lawrence M; Kish, John P

    2014-01-01

    The distal chevron osteotomy is a widely accepted technique for the treatment of hallux abductovalgus deformity. Although the osteotomy is considered to be stable, displacements of the capital fragment has been described. We propose a new method for fixation of the osteotomy involving the axial loading screw (ALS) used in addition to single screw fixation. We believe this method will provide a more mechanically stable construct. We reviewed the charts of 46 patients in whom 52 feet underwent a distal chevron osteotomy that was fixated with either 1 screw or 2 screws that included the ALS. We hypothesized that the ALS group would have fewer displacements and would heal more quickly than the single screw fixation group. We found that the group with ALS fixation had healed at a mean of 6.5 weeks and that the group with single screw fixation had healed at 9.53 weeks (p = .001). Also, 8 cases occurred of displacement of the capital fragment in the single screw, control group compared with 2 cases of displacement in the ALS group. However, this finding was not statistically significant. The addition of the ALS to single screw fixation allowed the patients to heal approximately 3 weeks earlier than single screw fixation alone. The ALS is a fixation option for the surgeon to consider when osseous correction of hallux abducto valgus is performed. Copyright © 2014 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  6. A Prospective Study of Distal Metatarsal Chevron Osteotomies with K-Wire Fixations to Treat Hallux Valgus Deformities

    Science.gov (United States)

    Baig, Usman; Tariq, Ali; Din, Robert

    2017-01-01

    Introduction Hallux valgus is one of the most common forefoot deformities worldwide. Females are affected more often than males. The three most common clinical symptoms are the painful bunion, transfer metatarsalgia, and hammer or claw toes. Methods This case series consisted of 20 patients who had chevron osteotomy from January 2015 to January 2016. The clinical assessment was measured by The American Orthopedic Foot and Ankle Score (AOFAS), and radiologic assessment was determined by preoperative and postoperative hallux valgus angle (HVA) and intermetatarsal angle (IMA). Results The patients’ mean age was 56 years. Out of 20 patients, 19 were female, and one was male. The mean AOFAS improved from 51 preoperatively to 82 postoperatively. The HVA improved from 26° preoperatively to 14°. There were five complications including four Kirschner (K)-wire complications. Conclusion Distal chevron osteotomy is a reliable and time-tested procedure. The K-wire fixation has a relatively high complication rate. We planned to use other methods of fixation and then compared them with K-wires fixation results for future studies. PMID:29167752

  7. Effect of fuel and nozzle geometry on the off-axis oscillation of needle in diesel injectors using high-speed X-ray phase contrast imaging

    International Nuclear Information System (INIS)

    Zhang, X.; Liu, J.; Wang, J.

    2016-01-01

    The diesel spray characteristics are strongly influenced by the flow dynamics inside the injector nozzle. Moreover, the off-axis oscillation of needle could lead to variation of orifice flow in the nozzle. In this paper, the needle oscillation was investigated using high-speed X-ray phase contrast imaging and quantitative image processing. The effects of fuel, injection pressure and nozzle geometry on the needle oscillation were analyzed. The results showed that the vertical and horizontal oscillation of needle was independent on the injection pressure. The maximum oscillation range of 14μ m was found. Biodiesel application slightly decreased the needle oscillation due to high viscosity. The needle oscillation range increased generally with increasing hole number. The larger needle oscillation in multi-hole injectors was dominated by the geometry problem or production issue at lower needle lift. In addition, the influence of needle oscillation on the spray morphology was also discussed.

  8. Effect of fuel and nozzle geometry on the off-axis oscillation of needle in diesel injectors using high-speed X-ray phase contrast imaging

    Science.gov (United States)

    Zhang, X.; Liu, J.; Wang, J.

    2016-05-01

    The diesel spray characteristics are strongly influenced by the flow dynamics inside the injector nozzle. Moreover, the off-axis oscillation of needle could lead to variation of orifice flow in the nozzle. In this paper, the needle oscillation was investigated using high-speed X-ray phase contrast imaging and quantitative image processing. The effects of fuel, injection pressure and nozzle geometry on the needle oscillation were analyzed. The results showed that the vertical and horizontal oscillation of needle was independent on the injection pressure. The maximum oscillation range of 14μ m was found. Biodiesel application slightly decreased the needle oscillation due to high viscosity. The needle oscillation range increased generally with increasing hole number. The larger needle oscillation in multi-hole injectors was dominated by the geometry problem or production issue at lower needle lift. In addition, the influence of needle oscillation on the spray morphology was also discussed.

  9. Heat transfer and pressure drop characteristics of a plate heat exchanger using water based Al2O3 nanofluid for 30° and 60° chevron angles

    Science.gov (United States)

    Elias, M. M.; Saidur, R.; Ben-Mansour, R.; Hepbasli, A.; Rahim, N. A.; Jesbains, K.

    2018-04-01

    Nanofluid is a new class of engineering fluid that has good heat transfer characteristics which is essential to increase the heat transfer performance in various engineering applications such as heat exchangers and cooling of electronics. In this study, experiments were conducted to compare the heat transfer performance and pressure drop characteristics in a plate heat exchanger (PHE) for 30° and 60° chevron angles using water based Al2O3 nanofluid at the concentrations from 0 to 0.5 vol.% for different Reynolds numbers. The thermo-physical properties has been determined and presented in this paper. At 0.5 vol% concentration, the maximum heat transfer coefficient, the overall heat transfer coefficient and the heat transfer rate for 60° chevron angle have attained a higher percentage of 15.14%, 7.8% and 15.4%, respectively in comparison with the base fluid. Consequently, when the volume concentration or Reynolds number increases, the heat transfer coefficient and the overall heat transfer coefficient as well as the heat transfer rate of the PHE (Plate Heat Exchangers) increases respectively. Similarly, the pressure drop increases with the volume concentration. 60° chevron angle showed better performance in comparison with 30° chevron angle.

  10. Short-Term Radiographic Outcome After Distal Chevron Osteotomy for Hallux Valgus Using Intramedullary Plates With an Amended Algorithm for the Surgical Management of Hallux Valgus.

    Science.gov (United States)

    Matsumoto, Takumi; Gross, Christopher E; Parekh, Selene G

    2018-03-01

    Distal Chevron osteotomy is a well-established surgical procedure for mild to moderate hallux valgus deformity. Many methods have been described for fixation of osteotomy site; secure fixation, enabling large displacement of the metatarsal head, is one of the essentials of this procedure. The purpose of the present study was to evaluate the short-term radiographic outcome of a distal Chevron osteotomy using an intramedullary plate for the correction of hallux valgus deformity. The present study evaluated 37 patients (40 feet) who underwent distal Chevron osteotomy using an intramedullary plate by periodic radiographs obtained preoperatively and at 4 weeks, 8 weeks, 3 months, and 6 months postoperatively. Correction of the hallux valgus angle averaged 17.8°, intermetatarsal angle 7.4°, distal metatarsal articular angle 2.7°, and sesamoid position 1.4 stages at 3 months postoperatively. The average lateral shift of the capital fragment was 6.5 mm. All patients achieved bone union, and there were no cases of dislocation, displacement, or avascular necrosis of the metatarsal head fragment. In conclusion, a distal Chevron osteotomy using an intramedullary plate was a favorable method for the correction of mild to moderate hallux valgus deformity. Level IV: Case series.

  11. Altitude Compensating Nozzle Transonic Performance Flight Demonstration, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Altitude compensating nozzles continue to be of interest for use on future launch vehicle boosters and upper stages because of their higher mission average Isp and...

  12. Design methods of Coanda effect nozzle with two streams

    Directory of Open Access Journals (Sweden)

    Michele TRANCOSSI

    2014-03-01

    Full Text Available This paper continues recent research of the authors about the ACHEON Coanda effect two streams nozzle. This nozzle aims to produce an effective deflection of a propulsive jet with a correspondent deviation of the thrust vector in a 2D plane. On the basis of a previously published mathematical model, based on integral equations, it tries to produce an effective design guideline, which can be adopted for design activities of the nozzle for aeronautic propulsion. The presented model allows defining a governing method for this innovative two stream synthetic jet nozzle. The uncertainness level of the model are discussed and novel aircraft architectures based on it are presented. A CFD validation campaign is produced focusing on validating the model and the designs produced.

  13. Characterization of Plasmadynamics within a Small Magnetic Nozzle

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal presents an experimental and theoretical research project intended to develop a more refined model of the underlying physics of magnetic nozzles. The...

  14. Separation of a light additive gas by separation nozzle cascades

    International Nuclear Information System (INIS)

    Becker, E.; Bley, P.; Ehrfeld, W.; Fritz, W.; Steinhaus, H.

    1984-01-01

    Double-turn separation nozzles, in comparison with single-turn separation nozzles, offer much greater advantages in the separation of UF6 and H2 than in the separation of the U isotopes, for which the double-turn separation nozzles were conceived. By using a double-turn separation-nozzle stage as a preseparation stage in combination with a low-temperature separator, one can reduce the ratio of the buffer input stream to the product stream, in contrast with the solution used up to this time, with only a slight increase in cost of about an order of magnitude. The control program in the case of return feeding of the UF6 from the buffer and the danger of production losses connected with it are thereby correspondingly diminished. An example is given of the enrichment of 235U using the title facility with UF6. (orig./PW)

  15. Optimal Thrust Vectoring for an Annular Aerospike Nozzle, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Recent success of an annular aerospike flight test by NASA Dryden has prompted keen interest in providing thrust vector capability to the annular aerospike nozzle...

  16. Analysis of the Vortex Street Generated at the Core-Bypass Lip of a Jet-Engine Nozzle

    Science.gov (United States)

    Nogueira, José; Legrand, Mathieu; Nauri, Sara; Rodríguez, Pedro A.; Lecuona, Antonio

    The reduction of the noise generated by jet-engine aircrafts is of growing concern in the present society. A better understanding of the aircraft noise production and the development of predictive tools is of great interest. Within this framework, the CoJeN (Coaxial Jet Noise) European Project includes the measurement of the flow field and the noise generated by typical turbofan jet-engine nozzles. One of the many aspects of interest is the occasional presence of acoustic tones of a defined frequency, symptomatic of the presence of quasiperiodic coherent structures within the flow. This chapter analyzes the characteristics of a vortex street in the core-bypass lip of one of the nozzles under study. The measurements were made by means of advanced PIV techniques within the above-mentioned project.

  17. Development of methodology for evaluating and monitoring steam generator feedwater nozzle cracking in PWRs

    International Nuclear Information System (INIS)

    Shvarts, S.; Gerber, D.A.; House, K.; Hirschberg, P.

    1994-01-01

    The objective of this paper is to describe a methodology for evaluating and monitoring steam generator feedwater nozzle cracking in PWR plants. This methodology is based in part on plant test data obtained from a recent Diablo Canyon Power Plant (DCPP) Unit 1 heatup. Temperature sensors installed near the nozzle-to-pipe weld were monitored during the heatup, along with operational parameters such as auxiliary feedwater (AFW) flow rate and steam generator temperature. A thermal stratification load definition was developed from this data. Steady state characteristics of this data were used in a finite element analysis to develop relationship between AFW flow and stratification interface level. Fluctuating characteristics of this data were used to determine transient parameters through the application of a Green's Function approach. The thermal stratification load definition from the test data was used in a three-dimensional thermal stress analysis to determine stress cycling and consequent fatigue damage or crack growth during AFW flow fluctuations. The implementation of the developed methodology in the DCPP and Sequoyah Nuclear Plant (SNP) fatigue monitoring systems is described

  18. A comprehensive study on the effect of cavitation on injection velocity in diesel nozzles

    International Nuclear Information System (INIS)

    Javier López, J.; Salvador, F.J.; Garza, Oscar A. de la; Arrègle, Jean

    2012-01-01

    Highlights: ► Cavitation has an indirect effect on the effective injection velocity. ► Cavitation in the injector hole reduces locally the fluid viscosity. ► A lower viscosity leads to a more turbulent velocity profile. ► The more turbulent velocity profile justifies the increase in effective velocity. - Abstract: Results when testing cavitating injection nozzles show a strong reduction in mass flow rate when cavitation appears (the flow is choked), while the momentum flux is reduced to a lesser extent, resulting in an increase in effective injection velocity. So as to better understand the origin of this increase in effective injection velocity, the basic equations for mass and momentum conservation were applied to an injection nozzle in simplified conditions. The study demonstrated that the increase in injection velocity provoked by cavitation is not a direct effect of the latter, but an indirect effect. In fact, the vapor appearance inside the injection hole produces a decrease in the viscosity of the fluid near the wall. This leads to lower momentum flux losses and to a change in the velocity profile, transforming it into a more “top hat” profile type. This change in the profile shape allows explaining why the momentum flux reduction is not so important compared to that of the mass flow rate, thus explaining why the effective injection velocity increases.

  19. Study of Liquid Breakup Process in Solid Rocket Motor Nozzle

    Science.gov (United States)

    2016-02-16

    Laboratory, Edwards, CA Abstract In a solid rocket motor (SRM), when the aluminum based propellant combusts, the fuel is oxidized into alumina (Al2O3...34Chemical Erosion of Refractory-Metal Nozzle Inserts in Solid - Propellant Rocket Motors," J. Propulsion and Power, Vol. 25, no.1,, 2009. [4] E. Y. Wong...34 Solid Rocket Nozzle Design Summary," in 4th AIAA Propulsion Joint Specialist Conference, Cleveland, OH, 1968. [5] Nayfeh, A. H.; Saric, W. S

  20. Nozzle Mounting Method Optimization Based on Robot Kinematic Analysis

    Science.gov (United States)

    Chen, Chaoyue; Liao, Hanlin; Montavon, Ghislain; Deng, Sihao

    2016-08-01

    Nowadays, the application of industrial robots in thermal spray is gaining more and more importance. A desired coating quality depends on factors such as a balanced robot performance, a uniform scanning trajectory and stable parameters (e.g. nozzle speed, scanning step, spray angle, standoff distance). These factors also affect the mass and heat transfer as well as the coating formation. Thus, the kinematic optimization of all these aspects plays a key role in order to obtain an optimal coating quality. In this study, the robot performance was optimized from the aspect of nozzle mounting on the robot. An optimized nozzle mounting for a type F4 nozzle was designed, based on the conventional mounting method from the point of view of robot kinematics validated on a virtual robot. Robot kinematic parameters were obtained from the simulation by offline programming software and analyzed by statistical methods. The energy consumptions of different nozzle mounting methods were also compared. The results showed that it was possible to reasonably assign the amount of robot motion to each axis during the process, so achieving a constant nozzle speed. Thus, it is possible optimize robot performance and to economize robot energy.

  1. Stresses in reactor pressure vessel nozzles -- Calculations and experiments

    International Nuclear Information System (INIS)

    Brumovsky, M.; Polachova, H.

    1995-01-01

    Reactor pressure vessel nozzles are characterized by a high stress concentration which is critical in their low-cycle fatigue assessment. Program of experimental verification of stress/strain field distribution during elastic-plastic loading of a reactor pressure vessel WWER-1000 primary nozzle model in scale 1:3 is presented. While primary nozzle has an ID equal to 850 mm, the model nozzle has ID equal to 280 mm, and was made from 15Kh2NMFA type of steel. Calculation using analytical methods was performed. Comparison of results using different analytical methods -- Neuber's, Hardrath-Ohman's as well as equivalent energy ones, used in different reactor Codes -- is shown. Experimental verification was carried out on model nozzles loaded statically as well as by repeated loading, both in elastic-plastic region. Strain fields were measured using high-strain gauges, which were located in different distances from center of nozzle radius, thus different stress concentration values were reached. Comparison of calculated and experimental data are shown and compared

  2. Remedial measures for nozzles susceptible to PWSCC

    International Nuclear Information System (INIS)

    Hunt, E.S.

    1992-01-01

    Remediating primary water stress corrosion cracking (PWSCC) is usually directed towards one of the three causes of PWSCC, material susceptiability, tensile stress, and an aggressive environment. The most practical remedial measures for primary loop penetration of PWSCC are considered to be shot peening, electropolishing, stress relief, and electroplating. The objective of shot peening is to induce a comprehensive residual stress on surfaces of Inconel 600 which are exposed to aggressive environments. Experience with steam generator tubes has shown this method is most effective if applied before PWSCC occurs. If it has already occurred, then the peening may retard but not arrest the corrosion. Electroplating consists of plating the inside surface of the Inconel 600 penetration with pure nickel. One of the major problems with this method was in obtaining surfaces uniformly free from pitting and roughness. Electropolishing for PWSCC remediation would remove the high strength cold work surfaces on the insides of nozzles which are produced by mechanical working e.g. machining. 5 figs

  3. Influence of flow force on the flapper of a water hydraulic servovalve; Suiatsu servo ben no flapper ni sayosuru ryutairyoku no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Urata, E. [Kanagawa University, Kanagawa (Japan). Faculty of Engineering; Yamashina, C. [Ebara Research Co. Ltd., Kanagawa (Japan)

    1997-06-25

    In this paper flow force due to nozzle flow and its influence on the flapper-nozzle system for water hydraulic servovalves are discussed. The flow force acting on the flapper is estimated using the momentum theory, and expressed as a function of the nozzle pressure and flapper-nozzle gap. Analysis shows that the double nozzle flapper gives a quasilinear characteristic to the relationship between the force on the flapper, the flapper gap and the spool velocity. The numerical result based on the theory is used to estimate accuracy of the classical linear approximation. The flow force reduces the magnitude of the change of the nozzle back pressures which drive the spool of the water hydraulic valve, because the input moment acting on the armature is resisted by the moment due to the flow force. Experimental verification of the theory is also given. 7 refs., 10 figs., 1 tab.

  4. Hydrogen extraction from liquid lithium-lead alloy by bubbling with rotational jet nozzle

    International Nuclear Information System (INIS)

    Xie Bo; Yang Tongzai; Guan Rui; Weng Kuiping

    2010-01-01

    The technology of tritium extraction from lithium-lead alloy has been simulated, hydrogen extraction from lithium-lead alloy by bubbling with rotational jet nozzle being used to simulate tritium in the study based on the introduction of fluid dynamics to establish algebraic model. The results show that the higher than lithium-lead melting temperature, the higher cumulative hydrogen extraction efficiency, and gas holdup of bubble column is little affected by the impeller diameter. Gas holdup when using small aperture is slightly higher when using large aperture only at a high helium flow rate, but the smaller the aperture, the greater the bubble surface area, and a marked increase in intensity of flow circulation for liquid lithium-lead with the increase of helium flow rate, hydrogen extraction rate increases too. Moreover, influence of the jet rotational velocity on hydrogen extraction is limited. (authors)

  5. Separation nozzle: an aerodynamic device for large-scale enrichment of uranium-235

    International Nuclear Information System (INIS)

    Becker, E.W.; Bley, P.; Ehrfeld, U.; Ehrfeld, W.

    1977-01-01

    This paper gives a review of the flow and diffusion phenomena in the separation nozzle. It is shown that admixing of a light auxiliary gas offers inherent advantages for the separation of heavy isotopic molecules in a centrifugal flow. The UF 6 is accelerated to a high speed ratio by the light gas already at a low expansion of the mixture--i.e., favorable conditions for centrifugal separation are obtained while aerodynamic losses are kept low. In addition, isotope separation is enhanced because of the different diffusion velocities of the isotopes relative to the light gas. Typical rarefaction phenomena are observed in the curved jet; the molecular velocity distribution is bimodal in large regions of the flow, and a velocity slip between the heavy UF 6 and the light auxiliary gas occurs

  6. Flow visualization study of post critical heat flux region for inverted bubbly, slug and annular flow regimes

    International Nuclear Information System (INIS)

    Denten, J.G.; Ishii, M.

    1988-11-01

    A visual study of film boiling using still photographic and high- speed motion picture methods was carried out in order to analyze the post-CHF hydrodynamics for steady-state inlet pre-CHF two-phase flow regimes. Pre-CHF two-phase flow regimes were established by introducing Freon 113 liquid and nitrogen gas into a jet core injection nozzle. An idealized, post-CHF two-phase core initial flow geometry (cylindrical multiphase jet core surrounded by a coaxial annulus of gas) was established at the nozzle exit by introducing nitrogen gas into the annular gap between the jet nozzle two-phase effluent and the heated test section inlet. For the present study three basic post-CHF flow regimes have been observed: the rough wavy regime (inverted annular flow preliminary break down), the agitated regime (transition between inverted annular and dispersed droplet flow), and the dispersed ligament/droplet regime. For pre-CHF bubbly flow in the jet nozzle, the post-CHF flow (beginning from jet nozzle exit/heated test section inlet) consists of the rough wavy regime, followed by the agitated and then the dispersed ligament/droplet regime. In the same way, for pre-CHF slug flow in the jet core, the post-CHF flow is comprised of the agitated regime at the nozzle exit, followed by the dispersed regime. Pre-CHF annular jet core flow results in a small, depleted post-CHF agitated flow regime at the nozzle exit, immediately followed by the dispersed ligament/droplet regime. Observed post dryout hydrodynamic behavior is reported, with particular attention given to the transition flow pattern between inverted annular and dispersed droplet flow. 43 refs., 20 figs., 5 tabs

  7. A numerical study of cavitation phenomenon in a flapper-nozzle pilot stage of an electrohydraulic servo-valve with an innovative flapper shape

    International Nuclear Information System (INIS)

    Aung, Nay Zar; Li, Songjing

    2014-01-01

    Highlights: • The flapper with curved edge develops a significant cavitation in pilot stage. • The rectangular shape flapper significantly reduces cavitation in pilot stage. • The innovative flapper eliminates undesired transverse lateral force. • The innovative flapper maintains the same flow control capability and construction. - Abstract: The flapper-nozzle pilot stage, whose performance can be deteriorated by the generated flow cavitation phenomenon, is a vital segment in achieving precise control of electrohydraulic servo-valves. Aiming to find out a reasonable flapper shape to reduce cavitation, this paper presents a numerical study of cavitation phenomenon in a flapper-nozzle pilot stage with different flapper shapes. A simple rectangular shape, carefully designed without disturbing the flow control characteristics of the pilot stage, is set as an innovative flapper shape in this work. Cavitation phenomena in the pilot stage are simulated for both of the traditionally used flapper shape and the innovative flapper shape at flow conditions with various nozzle inlet pressures, 1 MPa to 7 MPa. Then, systematic comparison of resulted cavitation phenomena for the two different flapper shapes is carried out. The results confirm that, for both flapper shapes, cavitation commonly occurs along the nozzle tip wall beyond stagnation region. The curved edge in traditionally used flapper shape is a massive contributor of cavitation in the pilot stage and the selected innovative shape shows a significant reduction of cavitation on its surface. From the flow structure, it is also noticeable that undesired transverse lateral force of sheded vortices is eliminated by using the innovative flapper shape. Meanwhile, the innovative flapper shape highlights the same effectiveness on the performance of flow control as the traditionally used flapper shape. Thus, a simple and effective flapper shape is proposed for cavitation reduction in the flapper-nozzle pilot stage of an

  8. An experimental study on the effects of rectifiers on fluid flow

    International Nuclear Information System (INIS)

    Kawashima, G.

    1985-01-01

    This paper reports studies of various combinations of rectifiers and rectifying nets to measure fluid flow and in particular, the measurement of the flow through an orifice or nozzle, since they help to shorten the inlet length

  9. Unique Kutubu export system complete; production flowing

    International Nuclear Information System (INIS)

    McGovern, R.; Miller, G.

    1992-01-01

    First oil from near Lake Kutubu in Papua New Guinea began flowing in June through pipelines and marine facilities recently installed by Chevron Niugini Pty. Ltd. Production facilities were built near Lake Kutubu. The export pipeline was laid form the central production facility to landfall on the Kikori River - approximately 171 km (106 miles) away - and then another 56 miles to a platform in 66 ft of water in the gulf. From the platform, an oilspading line extends about 2.4 miles to the SPM in 83 ft of water where tankers will load oil at an initial design flowrate of 157,000 b/d

  10. Elliptic nozzle aspect ratio effect on controlled jet propagation

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S M Aravindh; Rathakrishnan, Ethirajan, E-mail: aravinds@iitk.ac.in, E-mail: erath@iitk.ac.in [Department of Aerospace Engineering, Indian Institute of Technology, Kanpur (India)

    2017-04-15

    The present study deals with the control of a Mach 2 elliptic jet from a convergent–divergent elliptic nozzle of aspect ratio 4 using tabs at the nozzle exit. The experiments were carried out for rectangular and triangular tabs of the same blockage, placed along the major and minor axes of the nozzle exit, at different levels of nozzle expansion. The triangular tabs along the minor axis promoted superior mixing compared to the other controlled jets and caused substantial core length reduction at all the nozzle pressure ratios studied. The rectangular tabs along the minor axis caused core length reduction at all pressure ratios, but the values were minimal compared to that of triangular tabs along the minor axis. For all the test conditions, the mixing promotion caused by tabs along the major axis was inferior to that of tabs along the minor axis. The waves present in the core of controlled jets were visualized using a shadowgraph. Comparison of the present results with the results of a controlled Mach 2 elliptic jet of aspect ratio 2 (Aravindh Kumar and Sathakrishnan 2016 J. Propulsion Power 32 121–33, Aravindh Kumar and Rathakrishnan 2016 J. Aerospace Eng. at press (doi:10.1177/0954410016652921)) show that for all levels of expansion, the mixing effectiveness of triangular tabs along the minor axis of an aspect ratio 4 nozzle is better than rectangular or triangular tabs along the minor axis of an aspect ratio 2 nozzle. (paper)

  11. Elliptic nozzle aspect ratio effect on controlled jet propagation

    International Nuclear Information System (INIS)

    Kumar, S M Aravindh; Rathakrishnan, Ethirajan

    2017-01-01

    The present study deals with the control of a Mach 2 elliptic jet from a convergent–divergent elliptic nozzle of aspect ratio 4 using tabs at the nozzle exit. The experiments were carried out for rectangular and triangular tabs of the same blockage, placed along the major and minor axes of the nozzle exit, at different levels of nozzle expansion. The triangular tabs along the minor axis promoted superior mixing compared to the other controlled jets and caused substantial core length reduction at all the nozzle pressure ratios studied. The rectangular tabs along the minor axis caused core length reduction at all pressure ratios, but the values were minimal compared to that of triangular tabs along the minor axis. For all the test conditions, the mixing promotion caused by tabs along the major axis was inferior to that of tabs along the minor axis. The waves present in the core of controlled jets were visualized using a shadowgraph. Comparison of the present results with the results of a controlled Mach 2 elliptic jet of aspect ratio 2 (Aravindh Kumar and Sathakrishnan 2016 J. Propulsion Power 32 121–33, Aravindh Kumar and Rathakrishnan 2016 J. Aerospace Eng. at press (doi:10.1177/0954410016652921)) show that for all levels of expansion, the mixing effectiveness of triangular tabs along the minor axis of an aspect ratio 4 nozzle is better than rectangular or triangular tabs along the minor axis of an aspect ratio 2 nozzle. (paper)

  12. A comparison of three radiation models for the calculation of nozzle arcs

    International Nuclear Information System (INIS)

    Dixon, C M; Yan, J D; Fang, M T C

    2004-01-01

    Three radiation models, the semi-empirical model based on net emission coefficients (Zhang et al 1987 J. Phys. D: Appl. Phys. 20 386-79), the five-band P1 model (Eby et al 1998 J. Phys. D: Appl. Phys. 31 1578-88), and the method of partial characteristics (Aubrecht and Lowke 1994 J. Phys. D: Appl. Phys. 27 2066-73; Sevast'yanenko 1979 J. Eng. Phys. 36 138-48), are used to calculate the radiation transfer in an SF6 nozzle arc. The temperature distributions computed by the three models are compared with the measurements of Leseberg and Pietsch (1981 Proc. 4th Int. Symp. on Switching Arc Phenomena (Lodz, Poland) pp 236-40) and Leseberg (1982 PhD Thesis RWTH Aachen, Germany). It has been found that all three models give similar distributions of radiation loss per unit time and volume. For arcs burning in axially dominated flow, such as arcs in nozzle flow, the semi-empirical model and the P1 model give accurate predictions when compared with experimental results. The prediction by the method of partial characteristics is poorest. The computational cost is the lowest for the semi-empirical model

  13. Plate fixation for proximal chevron osteotomy has greater risk for hallux valgus recurrence than Kirschner wire fixation.

    Science.gov (United States)

    Park, Chul-Hyun; Ahn, Ji-Yong; Kim, Yu-Mi; Lee, Woo-Chun

    2013-06-01

    The purpose of this study was to compare the results of hallux valgus surgery between feet fixed with Kirschner wires and those fixed with a plate and screws. Between December 2008 and November 2009, 53 patients (62 feet) were treated with proximal chevron osteotomy and distal soft tissue procedure for symptomatic moderate to severe hallux valgus deformity. Thirty-four patients (41 feet) were stabilised with Kirschner wires (K-wire group) and 19 patients (21 feet) were stabilised with a locking plate (plate group). Clinical results were assessed using American Orthopaedic Foot and Ankle Society (AOFAS) score. Radiographic parameters were compared between these groups. Recurrence rate at the last follow-up was compared between the K-wire and plate groups. Mean AOFAS score was lower in the plate group, however, the difference between the groups was not statistically significant in AOFAS score at the last follow-up. Hallux valgus angle and intermetatarsal angle were significantly larger in the plate group at the last follow-up. Mean 1-2 metatarsal (MT) distance on immediately postoperative radiographs was significant larger in the plate group. Four (9.8 %) of the 41 feet in the K-wire group and 7 (33.3 %) of the 21 feet in the plate group showed hallux valgus recurrence at the last follow-up. The plate group had a significantly higher risk of recurrence than the K-wire group. Fixation of proximal chevron osteotomy using a plate and screws has a greater risk of hallux valgus recurrence than fixation using Kirschner wires.

  14. Set-up and calibration of an indoor nozzle-type rainfall simulator for soil erosion studies

    Science.gov (United States)

    Lassu, T.; Seeger, M.

    2012-04-01

    Rainfall simulation is one of the most prevalent methods used in soil erosion studies on agricultural land. In-situ simulators have been used to relate soil surface characteristics and management to runoff generation, infiltration and erosion, eg. the influence of different cultivation systems, and to parameterise erosion models. Laboratory rainfall simulators have been used to determine the impact of the soil surface characteristics such as micro-topography, surface roughness, and soil chemistry on infiltration and erosion rates, and to elucidate the processes involved. The purpose of the following study is to demonstrate the set-up and the calibration of a large indoor, nozzle-type rainfall simulator (RS) for soil erosion, surface runoff and rill development studies. This RS is part of the Kraijenhoff van de Leur Laboratory for Water and Sediment Dynamics in Wageningen University. The rainfall simulator consists from a 6 m long and 2,5 m wide plot, with metal lateral frame and one open side. Infiltration can be collected in different segments. The plot can be inclined up to 15.5° slope. From 3,85 m height above the plot 2 Lechler nozzles 460.788 are sprinkling the water onto the surface with constant intensity. A Zehnder HMP 450 pump provides the constant water supply. An automatic pressure switch on the pump keeps the pressure constant during the experiments. The flow rate is controlled for each nozzle by independent valves. Additionally, solenoid valves are mounted at each nozzle to interrupt water flow. The flow is monitored for each nozzle with flow meters and can be recorded within the computer network. For calibration of the RS we measured the rainfall distribution with 60 gauges equally distributed over the plot during 15 minutes for each nozzle independently and for a combination of 2 identical nozzles. The rainfall energy was recorded on the same grid by measuring drop size distribution and fall velocity with a laser disdrometer. We applied 2 different

  15. Critical flow rate in a single phase flow. Blocking concept

    International Nuclear Information System (INIS)

    Giot, Michel

    1978-01-01

    After referring to the phenomena accompanying the appearance of a critical flow rate in a nozzle and presenting equations governing single phase flows, the critical condition is defined. Several particular cases are then examined; the horizontal and vertical isentropic flow, Fanno's flow and Raleigh's and the isothermal flow. The entropy deviation is calculated on either side of a normal impact. To conclude, the link existing between the concepts of critical flow and the propagation rate of small perturbations is demonstrated. To do so, the method of perturbations, that of Prandtl and that of characteristic directions are applied in turn [fr

  16. The role of nozzle convergence in diesel combustion

    Energy Technology Data Exchange (ETDEWEB)

    J. Benajes; S. Molina; C. Gonzaalez; R. Donde [CMT-Motores Termicos, Universidad Politecnica de Valencia, Valencia (Spain)

    2008-08-15

    An experimental study has been performed for identifying the role of injector nozzle hole convergence and cavitation in diesel engine combustion and pollutant emissions. For doing so, five nozzles were tested under different operating and experimental conditions. The critical cavitation number of each nozzle was analyzed. With this value, an estimation of the mixing process at different conditions obtained. This data is used to explain the combustion results which are analyzed in terms of the apparent combustion time, rate of heat release, in-cylinder pressures, adiabatic temperatures and soot and NOx emissions. Special emphasis is put in developing an expression to explicitly link the mixing process and the injection rate with the rate of heat release. The results show that the fuel-air mixing process can be improved by the use of both convergent and cavitating nozzles, thus lowering the soot emissions. The NOx production, being dependent of the injection rate and the mixing process, does not necessarily increase with the use of more convergent nozzles. 40 refs., 8 fig., tabs.

  17. Hot Streak Characterization in Serpentine Exhaust Nozzles

    Science.gov (United States)

    2014-12-26

    computational results with experiments at General Electric (GE) Aircraft Engines. They used the CFD code PEPSI -G, a three-dimensional, subsonic, PNS...the treatment of flow separation. The PEPSI -G code did not allow for reverse flow but instead substituted a small positive value for any cells where...aforementioned PEPSI -G code was used with a first-order marching scheme and one-dimensional pressure field correction), some results and hypotheses are

  18. Stress analyses of flat plates with attached nozzles. Vol. 2: Experimental stress analyses of a flat plate with one nozzle attached

    International Nuclear Information System (INIS)

    Battiste, R.L.; Peters, W.H.; Ranson, W.F.; Swinson, W.F.

    1975-07-01

    Vol. 1 of this report compares experimental results with theoretical stress distributions for a flat plate with one nozzle configuration and for a flat plate with two closely spaced nozzles attached. This volume contains the complete test results for a flat plate with one nozzle attached that was subjected to 1:1 and 1:2 biaxial planar loadings on the plate, to a thrust loading on the nozzle, and to a moment loading on the nozzle. The plate tested was 36 x 36 x 0.375 in., and the attached nozzle had an outer dia of 2.625 in. and a 0.250-in.-thick wall. The nozzle was located in the center of the plate and was considered to be free of weld distortions and irregularities in the junction area. (U.S.)

  19. Numerical study of base pressure characteristic curve for a four-engine clustered nozzle configuration

    Science.gov (United States)

    Wang, Ten-See

    1993-07-01

    Excessive base heating has been a problem for many launch vehicles. For certain designs such as the direct dump of turbine exhaust in the nozzle section and at the nozzle lip of the Space Transportation Systems Engine (STME), the potential burning of the turbine exhaust in the base region has caused tremendous concern. Two conventional approaches have been considered for predicting the base environment: (1) empirical approach, and (2) experimental approach. The empirical approach uses a combination of data correlations and semi-theoretical calculations. It works best for linear problems, simple physics and geometry. However, it is highly suspicious when complex geometry and flow physics are involved, especially when the subject is out of historical database. The experimental approach is often used to establish database for engineering analysis. However, it is qualitative at best for base flow problems. Other criticisms include the inability to simulate forebody boundary layer correctly, the interference effect from tunnel walls, and the inability to scale all pertinent parameters. Furthermore, there is a contention that the information extrapolated from subscale tests with combustion is not conservative. One potential alternative to the conventional methods is computational fluid dynamics (CFD), which has none of the above restrictions and is becoming more feasible due to maturing algorithms and advancing computer technology. It provides more details of the flowfield and is only limited by computer resources. However, it has its share of criticisms as a predictive tool for base environment. One major concern is that CFD has not been extensively tested for base flow problems. It is therefore imperative that CFD be assessed and benchmarked satisfactorily for base flows. In this study, the turbulent base flowfield of a experimental investigation for a four-engine clustered nozzle is numerically benchmarked using a pressure based CFD method. Since the cold air was the

  20. Construction and evaluation of a hollow cone type nozzle with ceramic nanocomposites

    Directory of Open Access Journals (Sweden)

    F Amirshaghaghi

    2015-09-01

    products. In order to prepare nanocomposite powder mixed with stabilized zirconia alumina, the ratio of 10/90 percent by volume of the powder was poured into the mill for three hours and it was stirred in the mixer. Pressing is placing the powder into a mold, and applying pressure to achieve the desired density. In this study, pressing device with 30 tons was manually used and powder sample in the amount of one gram was placed in a semi-cylindrical small hollow. After making a few samples and determining the optimal pressure and time of pressing in action, samples were manufactured under 90 kg cm-2 pressure at 20 seconds. A high temperature furnace model F3L-1720 was used for zintering. Samples were put into the furnace after forming by a single-axis press. Temperature the of furnace was raised up 1650°C at a rate of 10 degrees per minute and then the samples were exposed for one hour in order for the heat to be evenly applied in all the body of the nozzle. Finally, a hollow cone spray pattern fan nozzle with a major diameter of 15 mm and an inner diameter of 2 mm was built. Equipment for analyzing used in this study included: X-Ray Diffraction device (XRD, Scanning Electron Microscope (SEM. The flow rate output was measured at a pressure of 2 bar in the period of 0-50 hours at 1, 2, 3, 4, 5, 8, 10, 15, 20, 25, 30, 40 and 50 hours. Results and Discussion: XRD analysis of nano-composite stabilizer in the presence of yttria- zirconia- alumina toughness with (Al2O3-ZrO2-Y2O3, yttria stabilized zirconia (ZrO2-Y2O3 and alumina indicates respective phases. For the samples made with better properties, it should be uniformly distributed within it. To evaluate the uniformity, SEM-Mapping test samples were made. The results showed that the distribution of Y, Zr, Al in nanocomposite (Al2O3-ZrO2-Y2O3 is almost uniform. The results of changes in the level of output over time showed that the rate of flow in composite (Al2O3-ZrO2-Y2O3 nozzle versus ceramic conventional (Al2O3 nozzle