Abstract: Geometrical parameters have great influences on the formation of gas bubbles or liquid droplets in the microchannel.The effects of gas inlet angle and cross-section aspect ratio on gas-liquid flow in the microchannel were investigated numerically by employing the volume of fluid (VOF) method.Generally, Taylor flow pattern could be observed in microchannels with various gas inlet angles and cross-section aspect ratios.A uniform distribution of bubble length could also be obtained under most circumstances.It was found that a 60° gas inlet angle helped to generate shortest bubble when cross-section aspect ratio was in the range of 0.5 to 2, while bubble length reached a minimal value when gas inlet angle was 45° and cross-section aspect ratio was 4 or 8.The dimensionless bubble length increased with increasing cross-section aspect ratio, and poor uniformity of bubble length distribution was observed when cross-section aspect ratio became larger.More specifically, a non-uniform bubble length distribution was observed when cross-section aspect ratio reached the value of 8.

Key words: gas-liquid flow, bubble length, microchannel, volume of fluid method

摘要： 微通道的几何参数对于气泡或者液滴在其中的形成过程有着显著的影响。采用流体体积法(VOF法)研究了不同气体入口角度以及不同通道截面宽高比对微通道内气液两相流流动状况的影响。在所研究的操作范围内,各个微通道内的两相流流型均为泰勒流,并且在大多数情况下气泡长度分布均匀。在通道截面宽高比为0.5～2条件下,60°的气体入口角度有利于产生较短的气泡;如果通道截面宽高比达到4或8时,45°的气体入口角度更有利于形成较短的气泡。此外,随着通道截面宽高比的增大,通道内气泡的量纲1长度也随之增大,气泡长度分布的均匀性也逐渐变差。当通道截面宽高比增大到8时气泡长度分布变得很不均匀。

关键词: 气液两相流, 气泡长度, 微通道, 流体体积法