T型微通道内气泡生成大小影响因素研究

Influential factors of bubble length in a T-junction microchannel

采用流体体积函数(VOF)方法,对T型微通道中气泡形成过程进行数值模拟研究,根据气泡形成机理,分析了气液流速、流体性质和微通道尺寸等因素对生成气泡大小的影响。研究结果表明,T型微通道内生成气泡长度随气体份额的增加呈指数增加趋势,而在相同气体份额下气液流速对气泡长度影响不大;比较而言,液体粘度和表面张力对生成气泡大小的影响较小,当液相表面张力从0.072 N·m-1降低到0.01 N·m-1时,T型微通道内生成气泡的长度减小了18%,主要是因为在阻塞阶段,最大颈部宽度和塌陷时间减小了;气泡长度随微通道直径的增加而增大,而气泡的无量纲长度基本不受微通道直径的影响。

We performed numerical simulation for bubble formation process in a T-junction microchannel with volume of fluid method （VOF）. We also analyzed the impact of gas/liquid fluid velocity, fluid properties and microchannel diameter on bubble length based on bubble formation mechanism. Results demonstrate that the bubble length exponentially increases with the increase of gas fraction in T-junction microchannel, but gas/liquid fluid velocity has little effect on bubble length for fixed gas fraction. Liquid viscosity and ＇surface tension comparatively have less effect on bubble length. When surface tension of liquid phase reduces from 0.072 N m-1 to 0.01 N m-1, the bubble length in T-junction microchannel decreases by 18%. This is because that maximum neck width and collapse time decrease in expansion stage of bubble formation process. The bubble length increases with the increase of microchannel diameter, but dimensionless length of the bubble is less influenced by microchannel diameter.