The Experts below are selected from a list of 24 Experts worldwide ranked by ideXlab platform
Raine Friedrich - One of the best experts on this subject based on the ideXlab platform.
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les of supersonic turbulent Flow in Nozzles and diffusers
International Journal of Heat and Fluid Flow, 2016Co-Authors: Somnath Ghosh, Susila Mahapatra, A Dubey, A Thagela, Raine FriedrichAbstract:Abstract Large-eddy simulations of supersonic nozzle and diffuser Flows with circular cross-sections using high-order compact schemes and an explicit filtering version of the approximate deconvolution method are presented in this paper. Two Flow cases each for nozzle and diffuser having different outlet to inlet area ratios are presented. The effect of the geometry variations on the Reynolds stresses as well as on the production and pressure-strain terms in their transport equations is demonstrated. A Green’s function analysis of the Poisson equation for pressure fluctuations using LES data is presented and the results show similar trends as found in previous analyses using DNS data. The effects of geometry changes on the rapid and slow parts of pressure-strain correlations is also demonstrated.
Wenju Zhong - One of the best experts on this subject based on the ideXlab platform.
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experimental study of Flow regime characteristics in diesel multi hole Nozzles with different structures and enlarged scales
International Communications in Heat and Mass Transfer, 2014Co-Authors: Wenju Zhong, Qia Wang, Zhuang Shao, Xicheng TaoAbstract:Abstract The internal Flow of diesel Nozzles has a strong influence on the subsequent spray and atomization characteristics. A Flow visualization experiment system equipped with enlarged transparent Nozzles was set up to investigate the effect of different nozzle structures and different nozzle enlarged scales on cavitating Flow and subsequent spray characteristics. Significant parameters of internal Flow including critical pressure of cavitation inception, critical pressure of hydraulic flip, discharge coefficient, Reynolds number, Flow rate and cavitation distribution were fully investigated during the experiments. Experimental results show that the Nozzles with small length/diameter ratios at the same orifice diameter were more inclined to cavitate and had higher discharge coefficient than that of Nozzles with large length/diameter ratios. Cavitating Flow in Nozzles with different sac volume structures may incur different spray characteristics in the near-nozzle field and it is the internal cavitating Flow that induces the asymmetry of subsequent spray. The investigations indicate that the critical pressure of hydraulic flip and discharge coefficient of Nozzles under different needle lifts were quite different even under the same boundary conditions and the nozzle Flow characteristics have been greatly influenced by the hydraulic flip phenomenon. Two types of cavitation were observed in Nozzles with different scaled-up times and the string cavitation was found in three times scaled-up nozzle, while the cloud cavitation bubbles were appeared in five and eight times scaled-up Nozzles. A kind of hysteretic cavitation phenomenon was also observed in the experiment and then was analyzed in this paper.
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an investigation of transient nature of the cavitating Flow in injector Nozzles
Applied Thermal Engineering, 2013Co-Authors: Wenju Zhong, Qia Wang, Zhaoche JiangAbstract:Abstract 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.
Krystia Smolka - One of the best experts on this subject based on the ideXlab platform.
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experimental study of condensing steam Flow in Nozzles and linear blade cascade
International Journal of Heat and Mass Transfer, 2015Co-Authors: Slawomi Dykas, Miroslaw Majku, Michal Strozik, Krystia SmolkaAbstract:Abstract Experimental investigations of non-equilibrium spontaneous condensation in transonic steam Flow were carried out in Nozzles and linear blade cascade. For the tests the geometry of the half arc Nozzles were used. The linear cascade consists of the stator blades of the last stage low pressure steam turbine. The applied experimental test section is a part of small scale steam power station located at the Silesian University of Technology. The steam parameters at the test section inlet correspond to the real conditions in low pressure part of steam turbine. The static pressure measurements as well as the Schlieren pictures were used to assess the Flow field in Nozzles and linear stator blades cascade. The capabilities of used measurement techniques were estimated for gaining insight into condensation process in steam Flow. The experimental results were compared with numerical calculations carried out by means of an in-house CFD code.
Ro Darby - One of the best experts on this subject based on the ideXlab platform.
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evaluation of two phase Flow models for flashing Flow in Nozzles
Process Safety Progress, 2000Co-Authors: Ro DarbyAbstract:A variety of methods and models have been proposed in the literature for sizing relief valves for two-phase Flow applications. A typical application involves liquids which flash during discharge as the pressure drops. The predictions from these various methods can vary greatly under such circumstances, and can also deviate as much as 300% from measured values. This paper compares predictions from several versions of the homogeneous equilibrium and non-equilibrium models with data from the literature for flashing of initially subcooled and low quality steam-water mixtures through Nozzles of various lengths. The results indicate that the homogeneous equilibrium model gives reasonable results for nozzle lengths greater than about six inches, but non-equilibrium effects must be taken into account for shorter Nozzles. Both the Fauske model with no adjustable parameters and the TPHEM model with appropriate values of the non-equilibrium parameter (kne) are shown to give good results for short Nozzles and subcooled or low quality inlet conditions.
Yu A Chulyuni - One of the best experts on this subject based on the ideXlab platform.
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numerical study of the gas Flow in Nozzles and supersonic jets for different values of specific heats
Journal of Physics: Conference Series, 2015Co-Authors: L G Gvozdeva, Yu A ChulyuniAbstract:The process of the issuing of a supersonic jet from a flat tapered nozzle has been investigated with two values of ratio of isobaric to isochoric specific heats (γ = cp/cV) and different parameters NPR (nozzle pressure ratio) on the basis of numerical modeling. NPR parameter represents the ratio of the pressure at the nozzle inlet to the pressure in the environment. As a result the solid state grid model have been created for the numerical simulations of the Flow of gas inside the nozzle and jet formation of compressed gas from the nozzle, which can be used to analyze the data structure. For the same value of the parameter NPR, but at a smaller value of γ an intersection point shifts further away from the inlet section of the nozzle. The Flow separation becomes substantially less.