为研究半椭圆管水平降膜厚度的分布规律，搭建逆向气流条件下水平降膜实验平台，并结合数字图像处理技术，研究逆流风速(0~5 m/s)和喷淋流量(0.025~0.221 L/min)对液膜厚度的影响。研究表明：逆向气流会对管外水膜产生影响，并存在临界速度；当逆流风速低于临界速度，液膜厚度沿圆周方向先减小后增大，与无空气流动时相似；当逆流风速超过临界速度时，液膜分布严重不均甚至被吹飞；随着逆流风速增大，平均液膜厚度先增大后减小；随着喷淋流量增大，平均液膜厚度持续增大；当喷淋流量减小、逆流风速增大时，平均液膜厚度减小。

In order to study the distribution of the horizontal film thickness outside the semielliptical tube,an experimental platform for horizontal falling film was built under countercurrent airflow.Combined with digital image processing technology,the influence of countercurrentairflow speed (0~5 m/s) and spray flow rate (0.025~0.221 L/min) on the liquid film thickness were investigated.The results show that the countercurrent airflow has an effect on the liquid film outside semielliptical tube,and the critical velocity exists.When the speed of countercurrent airflow is lower than critical speed,liquid film thickness decreases first and then increases along circumferential angle,which is similar to that without airflow.When the countercurrent airflow speed exceeds the critical speed,the distribution of liquid film is severely uneven or even blown away.The average liquid film thickness increases first and then decreases with the increase of countercurrent airflow speed.With the increase of spray flow,the average liquid film thickness continues to increases.When spray flow decreases and the countercurrent air speed increases,the average liquid film thickness decreases.

TK124