化工学报 ›› 2018, Vol. 69 ›› Issue (7): 2851-2859.DOI: 10.11949/j.issn.0438-1157.20171309

• 流体力学与传递现象 • 上一篇    下一篇

方形微通道内流动凝结时气液相界面演进过程的数值模拟

吴春旭, 李俊明   

  1. 清华大学能源与动力工程系, 热科学与动力工程教育部重点实验室, 北京 100084
  • 收稿日期:2017-09-27 修回日期:2018-03-26 出版日期:2018-07-05 发布日期:2018-07-05
  • 通讯作者: 李俊明
  • 基金资助:

    国家自然科学基金项目(51576106);科技部国家重点研发计划政府间国际科技创新合作重点专项(2016YFE0133300);牛顿基金-中英校企合作项目(UK-CIAPP\415);国家自然科学基金创新研究群体项目(51621062)。

Numerical simulation of gas-liquid interface evolution for flow and condensation in square microchannel

WU Chunxu, LI Junming   

  1. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
  • Received:2017-09-27 Revised:2018-03-26 Online:2018-07-05 Published:2018-07-05
  • Supported by:

    supported by the National Natural Science Foundation of China (51576106), the Key Special Foundation of National Key Research Program of the Ministry of Science and Technology (2016YFE0133300), the UK-China Industry Academia Partnership Programme (UK-CIAPP\415) and the National Natural Science Foundation for Creative Research Groups of China (51621062).

摘要:

基于VOF模型,模拟了R32在水力直径为50 μm的方形微通道内流动凝结时的气液两相流型演进过程,模拟涉及的流型包括环状流、喷射流、泡状流和收缩泡状流。模拟结果显示,由于沿通道周向气液界面存在曲率差异,凝结液内部存在表面张力导致的横向压力梯度,驱使凝结液流向通道壁面拐角处,减薄通道壁面中部液膜厚度。基于势能最小原理,解释了表面张力与界面黏性力主导的喷射流形成机理。小质量流率时,喷射流诱发环状流上游气液界面波动,界面波动在界面黏性力的作用下逐渐生长。这与大质量流率时,流向下游并逐渐生长的界面波动导致流型转换的机理不同。

关键词: 凝结, 微通道, 喷射流, 界面波动

Abstract:

Based on the fluid volume approach, the gas-liquid interface evolution for R32 flow and condensation in a square microchannel with 50 μm hydraulic diameter is studied. Annular, injection flow, bubbly flow and shrinking bubbly flow are simulated successively. Because of the gas-liquid interface curvature variation along the circumferential direction of channel, the existing surface tension generated transverse pressure gradient in the condensate film, which forces the condensate towards the corners and thins the condensate film at the middle of the wall of channel. A mechanism for the occurrence of injection flow dominated by the surface tension force and interface viscous force is proposed based on the minimum potential energy theory. The interface fluctuations on the annular flow upstream are induced by injection flow at low mass flux, and grow up gradually under interface viscous force which is different from the mechanism of “flow pattern transition at high mass flux being induced by interface fluctuations which grow up while flowing downstream”.

Key words: condensation, microchannel, injection flow, interfacial fluctuation

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