第四届多相流国际会议于2001年5月27日到6月1日在美国新奥尔良市举行。来自世界各地的800余位代表出席了会议，就多相流研究与发展的各个方面及其应用进行了交流与讨论。会议共组织大会报告4篇，特邀报告16篇，宣读论文445篇，展示论文85篇，并组织了3次专题 讨论，22个小型论坛，还有不少单位放映了专门的研究录相，会议开得隆重热烈，取得圆满成功。随着多相流研究的发展，于1991年9月在日本筑波市举行了第一届多相流国际会议，在此之后成立了国际学术委员会，确定每三年举行一次，成为多相流领域学术水平最高的系列性国际会议。下次会议定于2004年在日本横滨市举行。
    在本届会议上，4篇大会报告的题目为：
    1. Drop deformation, breakup and coalescence in viscous fluids
    2. Forced convective subcooled boiling
    3. Discrete particle simulation of particle-fluid flows
    4. A review of carrier-phase turbulence in dispersed phase flows
    16篇特邀报告的题目为：
    1. The physics of boiling at burnout
    2. Direct numerical simulation of multiphase flow
    3. Opaque multiphase flows: Experiments and Modeling
    4. Multi-scale analysis of bubbly flows - pressure wave phenomena
    5. The role of particle collisions in single-phase and multi-phase flows
    6. Two-phase flow in micro-channels
    7. Hydrodynamics of fluidization: Structure and Turbulence
    8. Examples of interesting industrial multiphase flow problems
    9. Multiphase phenomena and processes at the nanoscale
    10. Gas-particle flows around bodies - Key problems, Modeling and Numerical analysis
    11. Turbulence and mixing in bubbly flows
    12. Recent developments and applications of non-intrusive optical techniques for the analysis of dispersed multiphase flow
    13. The systematic derivation of averaged equations by direct numerical simulation
    14. On the PDF approach for modeling dispersed particle flows
    15. Boiling with surfactants
    16. Recent advances in the second-order moment two-phase turbulence-models for gas-particle and bubble-liquid flows
    3次专题讨论的题目为：
    1. 微重力两相流
    2. 两相流实验方法的最新发展
    3. 核反应堆热工水力新水平
    我校陈学俊、林宗虎、陈听宽、罗毓珊四位代表出席了会议，在会上共宣读和发表了论文7篇。
    1. 郭烈锦、李广军、陈斌、陈学俊，Study on gas-liquid two-phase spraying characteristics of nozzles for the humidification of smoke
    2. 陈学俊、李广军、郭烈锦，Interfacial waves in horizontal and near-horizontal stratified two-phase flows
    3. 林宗虎、牛冬梅、王祺、王树众、苏新军，An experimental study of gas-oil-water three-phase flow characteristics in horizontal pipes
    4. 王树众、林宗虎、王祺、牛冬梅，Experimental studies on the frictional pressure drop of oil-water-air three phase flow in vertical downward pipeline
    5. 王栋、林宗虎，Gas-liquid two-phase flow measurement using ESM
    6. 罗毓珊、蔡继勇、陈听宽，Study on the bubble and intermittent flow patterns and its transition for air/oil-water emulsions
    7. 陈听宽、徐进良、宋纪元、罗毓珊，Two-phase critical flow in sharp-edged tubes at high pressures
    TWO-PHASE CRITICAL FLOW IN SHARP-EDGED TUBES AT HIGH PRESSURES
    Tingkuan Chen Jinliang Xu Jiyong Song Yushan Luo
    State Key Laboratory of Multiphase Flow in Power Engineering,
    Xi"an Jiaotong University, Xi"an, Shaanxi, 710049, CHINA
    E-mail: chentk@xjtu.edu.cn Fax: 0086-29-2669033
    ABSTRACT
    In nuclear power reactor system the discharge rate from pressurized containers under the conditions of a loss-of-coolant accident (LOCA) determines the pressure decompression rate, the coolant level within the reactor vessel, and the design of the emergency core-cooling system (ECCS) etc. The prediction accuracy of the flow rate discharging from break is not enough due to the difficulties of considering both interphase thermal nonequilibrium and interphase relative motion. The maximum discharge rate (critical flow) is dependent upon the initial state of the fluid, the entrance geometry and the length to diameter ratio of the break. The last two items are also not taken into account by the equilibrium models.
    In this paper, the transient critical flow experiments with sharp-edged tubes as the break geometries are conducted at the high pressure test loop of Xi"an Jiaotong University. The initial pressure is from 4 MPa to 22 MPa and the initial subcooling of the liquid is from 0℃-60℃. The break section consists of the break tube and a fast-closing globe valve. When the circuit is operated under the conditions of controlled system pressure, flow rate and subcooling, the fast-closing valve is opened suddenly very fast. The hot water then discharges through the break section, enters a short expansion tube and is collected by a catch tank. The catch tank is supported vertically on the two load cells. By use of the two load cells, the time dependent mass of the catch tank can be obtained, therefore the discharge flow rate through the break tube may be determined by differential technique. Five test tubes with different ratio of break tube length to diameter from 1.01 to 25.61, including one orifice plate, two short tubes (L/D<12) and two long tubes (L/D>12). Based on the experimental results, an empirical correlation is established to predict the critical flow rates for inlet saturated and subcooled water at various system pressures. The critical flow pressure ratio and the thermal nonequilibrium number are correlated as the functions of the tube length to tube diameter ratio L/D. The predicted critical flow rates have a higher accuracy and may be used for design of nuclear power plant.
    STUDY ON THE BUBBLE AND INTERMITTENT FLOW PATTERNS AND ITS TRNASITION FOR AIR/OIL-WATER EMULSIONS
    Yushan Luo Jiyong Cai Tingkuan Chen
    State Key Laboratory of Multiphase Flow in Power Engineering
    Xi"an Jiaotong University, Xi"an, Shaanxi, 710049, China
    Tel: 86-29-2668707 Fax: 86-29-2669033 E-mail: yshluo@xjtu.edu.cn
    Keywords: air/oil-water emulsions, flow pattern transition, vertical downward pipe
    ABSTRACT
    The experimental investigation on flow patterns and its transition for air/oil-water emulsions in vertical downward pipe has been undertaken. The test section is a steel tube with inner diameter of 44mm and length of 1.5m . In the test series the input water fraction in oil-water emulsions is varied between 0%(pure oil) and 100%(pure water). The test pressure are varied between 0.1 MPa and 0.5 MPa, the temperatures are varied from 10 to 40℃,air superficial velocity Vsg=0.1~26m/s, oil-water emulsions superficial velocity Vsl=0~2.5m/s. The type of test oil is 46 machine tool.
    In this paper, the phase inversion point between w/o and o/w is obtained. The water fraction is 0.51 at the phase inversion is occused. The transition of flow patterns will occur with changing of flow velocity when air/oil-water emulsions flow in pipe, and pressure drop pulsation will also occur at same time. In the experiment a group of data which determine flow pattern has been got in vertical downward pipe by study and analysis to pressure drop pulsation.
    In w/o case the transition from dispersed bubble to intermittent is easy occurred with increase of water fraction, but in o/w case the transition is just reverse. In this paper the predictable model for flow patterns transition were established. The predictable model was in good agreement with the experimental results. This model is more suitable to air/oil-water emulsions three phase flow than other model.