Abstract: A high-speed camera was used to visualize and determine the size of formed droplet for liquid-liquid two-phase flow in the T-junction microchannels with different aspect ratios.Microchannels with different dimensions of 400 μm×400 μm, 400 μm×600 μm, 400 μm×800 μm in depth and width were used in this work.Cyclohexane and deionized water with 0.3% surfactant sodium dodecyl sulfate (SDS)-glycerol (20%,40%,60%) were used as the oil (dispersed) and water (continuous) phases, respectively.The effects of microchannel geometry, flow rates of both phases and physical properties of fluids on the size of droplet formed were investigated in the slug, transient and droplet regimes.The result showed that the droplet size decreased with increasing flow rate, viscosity and capillary number of the continuous phase, while it increased with increasing width of microchannels and flow rate of the dispersed phase.The correlations for predicting the size of formed droplet were proposed in taking capillary number, ratio of oil/water flow rates and aspect ratio of microchannels into account, and the calculated values by presented correlations agreed well with the experimental data.

Key words: microchannel, droplet, high speed camera, microfluidic

摘要： 利用高速摄像仪对不同深宽比的T型微通道内液滴尺寸进行了实验研究。分别采用3种不同尺寸(深度×宽度)的微通道:400 μm×400 μm、400 μm×600 μm、400 μm×800 μm。以环己烷为分散油相,含0.3%表面活性剂十二烷基硫酸钠(SDS)的蒸馏水-甘油(质量分数分别为20%、40%、60%)溶液为连续相。考察了弹状流、过渡流和滴状流流型下微通道尺寸、两相流率、物性对液滴尺寸的影响。结果表明:液滴尺寸随微通道深宽比、连续相流率、黏度和毛细数的增加而减小,随分散相流率的增加而增加。用毛细数、两相流量比和通道深宽比对微通道内液滴尺寸进行了关联和预测,预测值与实验结果吻合良好。

关键词: 微通道, 液滴, 高速摄像仪, 微流体