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Numerical Investigation of Developing Turbulent Flow in a Helical Square Ductwith Large Curvature

Journal of Thermal Science 2001年第1期10卷 1-6页

作者： Gao Hui,Guo Liejin (state key laboratory of multiphase Flow in power engineering, Xi’an Jiaotong University, Xi’an 710049, China ) State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

A fully elliptic numerical study has been carried out to investigate the three-dimensional turbulent developing flow in a helical square duct with large curvature. A two-layer zonal model is proposed and used, in which the whole region is divided into a viscosity-affected near wall layer and a fully turbulent region. A DSM closure is applied in the former, and a one-equation model is solved in the latter. The results presented in this paper cover a Reynolds number range of (l- 10) x 104. The development of flow is found to be dominated by radial pressure gradient and Dean-type secondary motion. The distribution of Reynolds stresses in fully developed flow exhibit a complex pattern of turbulence anisotropy The development of peripherally averaged friction factor and the distribution of local friction factor in fully developed flow are given and discussed.

关键词： curved pipe developing flow turbulence model numerical simulation.

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Distribution of void fraction for gas-liquid slug flow in an inclined pipe

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Nuclear Science and Techniques 2001年第2期000卷 143-148页

作者： XIA Guo-Dong ZHOU Fang-De HU Ming-Sheng College of Environmental and Energy Engineering Beijing Polytechnic University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

In order to investigate the effect of inclination angle on the spatial distribution of phases, experiments on gas-liquid two-phase slug flow in an inclined pipe were carried out by using the optical probe and an EKTAPRO 1000 high speed motion analyzer. It has been demonstrated that the inclination angle and the mixture velocity are important parameters to influence the distribution of void fraction for upward slug flow in the inclined pipe. At high mixture velocity, the gas phase profile is axial symmetry in the cross-section of the pipe. This is similar to that for vertical slug flow. In contrast, most of the gas phase is located near the upper pipe wall at low mixture velocity. By measuring the axial variation of void fraction along the liquid slug, it can be concluded that there is a high void fraction wake region with length of 3～4D in the front of liquid slug. In the fully developed zone of liquid slug, the peak value of the void fraction is near the upper wall.

关键词： Gas-liquid slug flow Void fraction Inclined pipe

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Numerical simulation of strongly swirling turbulent flows in a liquid-liquid hydrocyclone using the Reynolds stress transport equation model

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Science China(Technological Sciences) 2000年第1期43卷 86-96页

作者：陆耀军周力行沈熊 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Engineering Mechanics Tsinghua University Beijing 100084 China

The Reynolds stress transport equation model (DSM) is used to predict the strongly swirling turbulent flows in a liquid-liquid hydrocyclone, and the predictions are compared with LDV measurements . Predictions properly give the flow behavior observed in experiments, such as the Rankine-vortex structure and double peaks near the inlet region in tangential velocity profile, the downward flow near the wall and upward flow near the core in axial velocity profiles. In the inlet or upstream region of the hydrocyclone, the reverse flow near the axis is well predicted, but in the region with smaller cone angle and cylindrical section, there are some discrepancies between the model predictions and the LDV measurements. Predictions show that the pressure is small in the near-axis region and increases to the maximum near the wall. Both predictions and measurements indicate that the turbulence in hydrocy-clones is inhomogeneous and anisotropic.

关键词： strongly swirling flows numerical simulation hydrocyclone

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Transient convective heat transfer in a helical tube with steam-water two-phase flow under pressure drop type oscillations

Transient convective heat transfer in a helical tube with st...

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ASME 2000 International Mechanical engineering Congress and Exposition, IMECE 2000

作者： Guo, Lie-Jin Feng, Zi-Ping Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Province Xi'an710049 China

ISBN: (纸本)9780791826621

In the present paper the experiments for subcooled water flow and steam-water two-phase flow were conducted to investigate the effects of pulsation upon transient heat transfer characteristics in a closed-circulation helical-coiled tube steam generator. The non-uniform property of local heat transfer with steady flow was also examined. The secondary flow mechanism and the effect of interaction between the flow oscillation and secondary flow were analyzed cm the basis of the experimental data. Some new phenomena were observed and explained. A series of correlations were proposed for the average and local heat transfer coefficients both under steady and oscillatory flow conditions. The results showed that there were considerable variations in local and peripherally time-averaged Nusselt numbers for pulsating flow in a wide range of parameters. Systematic investigations of pressure drop type oscillations and their thresholds for steam-water two-phase flow in a uniformly heated helical tube were also reported. Copyright © 2000 by ASME

关键词： Drops

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Turbulent heat transfer in a horizontal helically coiled tube

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Heat Transfer 2000年第5期28卷

作者： Bofeng Bai Liejin Guo Ziping Feng Xuejun Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

An experiment has been conducted in detail to study the turbulent heat transfer in horizontal helically coiled tubes over a wide range of experimental parameters. We found that the enhancement of heat transfer in the coils results from the effects of turbulent and secondary flows. With Reynolds number increasing to a high level, the contribution of the secondary flow becomes less to enhance heat transfer, and the average heat transfer coefficient of the coil is closer to that in straight tubes under the same conditions. The local heat transfer coefficients are not evenly distributed along both the tube axis and the periphery on the cross section. The local heat transfer coefficients on the outside are three or four times those on the inside, which is half of the average heat transfer. A correlation is proposed to describe the distribution of the heat transfer coefficients at a cross section. The average cross-section heat transfer coefficients are distributed along the tube axis. The average value at the outlet section should not be taken as the average heat transfer coefficient. © 1999 Scripta Technica, Heat Trans Asian Res, 28(5): 395–403, 1999

关键词： turbulent heat transfer horizontal helically coiled tube secondary flow local heat transfer

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Experimental Study on the Characteristics of Liquid Layer and Disturbance Waves in Horizontal Annular Flow

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Journal of Thermal Science 1999年第4期8卷 235-242页

作者： Li Weidong Zhou Fangde Li Rongxian Zhou Lixing Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The mechanism for transporting liquid from the bottom of the pipe to the top still to be established in the prediction of the film thickness distribution in horizontal annular two-phase flow. To resolve this issue, using five parallel-wire conductance probes, time records of local liquid film thickness at five circumferential positions were collected. The characteristics of circumferential liquid film thickness profiles and its variation with gas and liquid velocities were obtained. The basic features of probability distribution function, probability density function, auto-correlation, cross-correlation and power spectrum density function of the disturbance waves in angular flow were studied respectively. The characteristics of circumferential profiles of disturbance waves and its variation with gas and liquid velocities were presented.

关键词： two-phase flow annular flow liquid layer disturbance wares.

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Turbulent heat transfer in a horizontal helically coiled tube

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Heat Transfer - Asian Research 1999年第5期28卷 395-403页

作者： Bai, Bofeng Guo, Liejin Feng, Ziping Chen, Xuejun State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University China

关键词： Heat transfer

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The Measurement of Oil,Gas and Water Flowrates in Three-Phase Slug Flow

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Chinese Journal of Chemical engineering 1998年第4期6卷 37-43页

作者：蔡继勇陈听宽罗毓珊 State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China

Three-sphase flow invo1ving oil-water two immiscible liquids and gas which is often foundin the fields of petroleum production has been studied in this paper.A new method with thecombination of a horizontal tube,a downward flow vertica1 tube and an orifice to measure theflowrates is *** this method the frictional pressure drop in the downward vertical tube isreplaced by that in the horizontal tube,the void fraction is derived from the gravitational pressuredrop,then the volume fraction of the individual phase can also be *** individual flowratescan be calculated when the water fraction is *** method is applicable for many kinds ofoil-wells to measure the flowrates of crude oil,natural gas and *** with other methods,the presented method involves fewer measuring *** experimental results proved quitegood accuracy of the method,with measurement deviation within 10%,and reliable results wereobtained under high Dressure conditions.

关键词： measurement flowrate three-phase flow slug flow

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Statistical characteristics of the interfacial waves in horizontal gas-liquid two-phase stratified flow

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Progress in Natural Science:Materials International 1998年第4期 3-5页

作者：李广军郭烈锦陈学俊陈永利 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an 710049 Xi’an Jiaotong University

The study of the interfacial waves is very important in understanding and grasping the laws of the phase interface exchange dynamics in gas-liquid two-phase flow. Based on a series of experiments and investigations, the statistical characteristics of the interfacial waves in gas-liquid two-phase stratified flow in both time and frequency domains are presented. The statistical parameters with variations of the gas and liquid superficial velocities are analyzed and discussed.

关键词： liquid film thickness gas-liquid two-phase flow interfacial waves statistical analysis.

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A hydrodynamic model for gas-liquid slug flow in inclined tubes

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Progress in Natural Science:Materials International 1998年第5期 3-5页

作者：夏国栋李施雄周芳德胡明胜 Beijing 100011 Beijing 100081 Beijing Institute of Technology China China Electric Power Technology Import and Export Corporation China) State Key Laboratory of Multiphase Flow in Power Engineering Vehicle Engineering College Xi’an 710049 Xi’an Jiaotong University

With the gas exchange between the Taylor bubble and the following liquid slug taken into consideration a physically-based hydrodynamic model has been developed for gas-liquid slug flow in vertical and inclined tubes, which can predict the flow characteristics of slug flow in vertical and inclined tubes. Some experimental data arc obtained to check the model. In comparison with previously published results, the prediction by this model is better and in good agreement with the experimental data.

关键词： gas-liquid two-phase flow inclined tubes hydrodynamic model.

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