Abstract: High speed digital camera was employed to investigate the liquid-liquid two-phase flow behavior in a double T-type microchannel with a rectangular cross-section， a hydraulic diameter of 0.176mm and an aspect ratio of 2.4. By changing the volumetric flow ratios of silicon oil （continuous phase） and water （dispersed phase），the two-phase flow pattern as well as the flow evolvement process were recorded and analyzed. At the upstream T-junction of the microchannel，the droplet，slug，wavy parallel，and parallel flow were observed. At the middle zone of the microchannel，a flow pattern map was presented on the basis of Weber numbers of water and oil. In addition，linear relationships between the dimensionless length of slug/droplet and water/oil flow ratios were established. Also，it was found that the velocity of slug/droplet was larger than the two-phase mixture superficial velocity，and a correlation for well predicting the velocity of slug/droplet was developed. Finally，droplet behaviors at the downstream T-junction of the microchannel were investigated，and two different flow modes，breaking and non-breaking were observed and analyzed. Corresponding two different regimes of breakup were singled out as well.

Key words: microchannel, visualization, liquid-liquid two-phase flow, flow pattern

摘要： 通过高速摄像对水力直径0.176mm、深宽比2.4的双T形矩形微通道内的液-液两相流动进行了可视化实验研究。改变连续相（硅油）和分散相（水）的流量比，记录分析了微通道不同部位油-水两相流的流型和流型发展演化情况。实验结果表明，在微通道上游T形部位的油-水两相流型主要包括滴状流、弹状流、波平行流和平行流；在微通道的中间部位，绘制了基于水和硅油量纲为1韦伯数的流型图，并将其与相关文献进行了比较。同时，发现微通道内液塞及液滴的长度（量纲为1）与油/水流量比之间存在线性关系，液塞/液滴速度比两相混合物表观速度大，建立了能够准确描述液塞/液滴运动速度的实验拟合公式。最后，研究了液滴在微通道下游T形部位的行为，观察到断裂和不断裂两种模式并进行了分析，给出了划分断裂与否的流型图。

关键词: 微通道, 可视化, 液-液两相流, 流型