撞击流内液滴碰撞后续发展行为

Subsequent development of collided droplets in impinging streams

为了探索撞击流内液滴碰撞后续发展行为,设计搭建了由激光点光源和高速数码摄像机构成的高速数码摄像系统及气液两相撞击流实验平台。利用高速数码摄像系统记录下同轴对置气液两相撞击流中液滴碰撞导致的融合聚结或二次雾化过程,通过处理记录下的液滴运动过程图像,分析了进口液滴粒径、速度、黏度以及液滴碰撞角度等对撞击流中液滴碰撞结果的影响规律。结果表明:随着进口液滴粒径和速度的无限增大,液滴碰撞后最终发生炸裂;进口液滴黏度越小、表面张力越大、Ohnesorge数越小,液滴碰撞后越容易破碎;在本实验条件下,液滴同轴同向运动发生碰撞时,液滴碰撞后全部聚结,当液滴以一定角度发生斜碰时,碰撞后发生拉伸断裂,而当液滴同轴相向运动发生碰撞时,液滴碰撞后可能发生反射分离也可能炸裂。

In order to study subsequent development of collided droplets in impinging streams, a high-speed digital camera system, consisting of laser point source and high-speed digital camera, and a gas-liquid two-phase experimental platform was designed. The high-speed digital camera system was used to record droplet coalescence or secondary atomization caused by collisions in coaxially opposite gas-liquid two-phase impinging streams. Images of droplet movement were processed to analyze influence of droplet size, velocity, viscosity, and impact angle on collision outcomes. The results showed that droplets would be busted upon collision with unlimited increase in size and velocity. As surface tension was increased but viscosity and Ohnesorge number were decreased, inlet droplets were more inclined to break. Under experimental conditions, droplets upon collision were coalesced when moved coaxially in the same direction, were stretchily separated when moved in a certain angle, and were reflexively separated or busted moved coaxially in the opposite direction.