气泡生长及脱离过程中下边缘的迁移行为

基于高速摄像技术记录静止液体中气泡生长及脱离过程,并采用Image-Pro Plus 6.0软件进行后处理,研究了两种管径下气泡生长过程的形状变化.实验结果表明:由于不同管径下气泡生长过程中起主导的作用力不同,导致小管径生成气泡的高宽比随时间变化呈先陡后缓的上升趋势,大管径生成气泡的高宽比随时间变化呈先缓后陡的上升趋势;由于生长前期不满足脱离条件,小管径生成的气泡会出现下边缘向液体侧迁移的现象;大管径生成的气泡在气液面与固液面夹角小于接触角时即达到脱离条件,因此不会出现迁移;3.80 mm气泡脱离上浮的临界高宽比稍大于9.28 mm气泡相应值.

Bubble Bottom Edge Migration Behavior During Bubble Growth and Detachment Process

The bubble growth and detachment was recorded using a high speed video technology. The post-processing of photos was completed by Image-Pro Plus 6.0 software. The bubble shape variation during bubble growth under the condition of two kinds of different tube diameters was investigated. The experimental results show that the dominant force during bubble growth is different for different diameter tube. The increment of bubble aspect ratio from the small diameter tube with time is greater at first and then becomes smaller， while that from the large diameter one with time is firstly smaller and then greater afterward. Since the bubble detachment condition cannot be satisfied for the small diameter tube， the bubble bottom edge migrates towards liquid side. On the other hand， the bubble detachment condition can be reached for the large tube when the angle between gas-liquid line and solid-liquid line is smaller than the contact angle， therefore the bubble bottom edge cannot migrate towards liquid side. The critical bubble aspect ratio for detachment of 3.80mm bubble is slightly larger than that of 9.28mm bubble.