台阶式单微通道内气泡生成动力学

采用高速摄像系统研究了台阶式微通道中气泡生成机理和尺寸变化规律。探究了气液相流量、液相黏度以及台阶宽度对气泡生成过程的影响机制。实验中分别采用不同质量浓度的甘油水溶液和氮气作为液相和气相。发现台阶式微通道中气泡的生成过程分为扩展、夹断和蓄能阶段。增大气相、液相流量，减小液相黏度使各阶段所消耗的时间减少。随液相黏度的增大夹断阶段消耗的时间逐渐变长，成为气泡生成过程中起主导作用的阶段。最后，基于台阶式微通道中气泡的生成机理，构建了气泡体积的预测式。

Dynamics of bubble formation in single step-type microchannel

The bubble formation mechanism and size variation in stepped microchannels were studied by using a high-speed camera system. In the experiment, different concentrations of glycerin aqueous solution and nitrogen were used as the liquid phase and the gas phase, respectively. The mechanism of bubble formation process was explored by changing the gas-liquid flow, liquid viscosity and step width. It was observed that the bubble formation process in the step-type microfluidic chips was divided into expansion, pinch-off and energy storage stages. Increasing the gas phase, liquid phase flow rate, and decreasing the liquid phase viscosity could reduce the time consumed in each stage. The consumption time of the pinch-off stage gradually became longer as the viscosity of the liquid phase increases, making it the predominant stage in the bubble formation process. Finally, the prediction formula for the volume of bubbles was constructed based on the bubble formation mechanism in the step-type microfluidic chips.