Droplet coalescence at microchannel intersection chambers with different shapes
Droplet coalescence at microchannel intersection chambers with different shapes
复制标题
不同形状的微通道交叉室的液滴聚结
作者：
Zhaomiao Liu;Xiang Wang;Rentuo Cao;Yan Pang
研究了微通道交汇室形状对液滴聚并过程的影响。设计了半圆形、三角形和弧形三种不同形状的气室，实现了液滴的迎面聚并。聚结过程可视化使用高速摄像系统和内部流动模式的解决使用微型PIV系统。对液滴的聚并位置、聚并时间和临界条件进行了实验分析。在弧形结中可以观察到直接聚结和后期聚结，而在半圆形结和三角形结中仅存在后期聚结。临界毛细管数Ca* 因工作系统或交叉形状的不同而不同。对于每种工作系统，曲面连接处的Ca* 均大于其它两个连接处的Ca *，并且对于每种交叉形状，其Ca * 均随粘度比的增大而减小。此外，不同的聚并情况下的速度场的特点进行了分析，深入了解的过程。
The influence of microchannel intersection chamber shape on the droplet coalescence process is investigated in this study. Three kinds of chamber shapes (half-round, triangle and camber) are designed to realize head-on droplet coalescence. The coalescence processes are visualized using a high-speed camera system and the internal flow patterns are resolved using a micro-PIV system. Experimental analyses on the coalescence position and coalescence time of droplets and the critical conditions are discussed. Both direct coalescence and late coalescence can be observed in the camber junction while only the late coalescence is present for the half-round and the triangle junction. The critical capillary number Ca* varies for different working systems or intersection shapes. Ca* in the camber junction is larger than that in the other two junctions for each working system and it decreases with the increase of the viscosity ratio for each intersection shape. Moreover, the characteristics of the velocity fields for different coalescence cases are analyzed for an in-depth understanding of the process.