中文摘要：

微通道内气液二相流的空隙率对管路内热质传递具有重要影响。利用高速摄像仪对4种不同深宽比的矩形截面微通道内空气-水二相流的流型进行实时观测和记录,对二相流型图进行了分析和计算,得到了不同流型时的空隙率。4种微通道尺寸（深度×宽度）分别为100μm×200μm,100μm×400μm,100μm×800μm,100μm×2 000μm。结果表明：对于弹状流,空隙率随着微通道截面深宽比的减小而降低,当流型为液环流时,空隙率随着微通道截面深宽比的减小而增加。在实验基础上,将截面深宽比作为参数提出了一个新的空隙率预测模型,计算结果显示：模型能对矩形截面微通道内气液二相流动空隙率进行很好的预测。

英文摘要：

The void fraction of gas-liquid two-phase flow in microchannels is of vital importance in heat and mass transfer processes.A high-speed camera was utilized for real-time observation and recordation of air-water two-phase flow patterns in rectangular cross-section microchannels with four different aspect ratios,and the void fractions under different flow regimes were obtained by analyzing and calculating the flow pattern images.Four microchannels with different dimensions of 100 μm × 200 μm,100 μm× 400 μm,100 μm × 800 μm and 100 μm× 2 000 μm in depth and width were used.The results show that the void fraction decreases in the slug flow pattern while increases in the annular flow pattern with the decreasing of aspect ratios.A new correlation of void fraction prediction was proposed with the aspect ratio as a variable,and the present model shows good predicting accuracy.