实验观测液滴撞击倾斜表面液膜的特殊现象

采用高速摄像仪以10000帧/s 的拍摄速度对液滴撞击倾斜表面液膜的过程进行了实验观测, 分析了液滴撞击倾斜表面液膜后的铺展、水花形成以及飞溅等现象, 考察了撞击角对液滴震荡变形过程的影响; 在此基础上, 定量讨论了液滴铺展速度随时间的变化规律, 揭示了液滴撞击速度和撞击角对前、后铺展因子及初始铺展速度的影响.观测发现, 在撞击角为28.0°–74.7°范围内, 随着撞击角的减小, 液滴在液膜表面的震荡变形程度增大; 前铺展因子随撞击速度的增大而增大, 随撞击角的减小而增大; 后铺展因子随撞击速度的增大几乎不发生变化, 但是随撞击角的增大而增大; 液滴初始铺展速度随撞击速度和撞击角的升高而增大. 关键词： 液滴撞击 倾斜液膜 铺展因子 铺展速度

Special phenomena of droplet impact on an inclined wetted surface with experimental observation

The phenomena of droplet impact on an inclined solid surface covered with a pre-existing liquid film are observed using high speed camera at 10000 frames per second. The processes of droplet spreading, liquid sheet formation, splashing and droplet oscillation are observed and analyzed. From the results the relationship between spreading velocity and time is discussed quantitatively. Besides, the effects of impact velocity and impact angle on front and back spreading factors and initiatory spreading velocity are also revealed. At the impact angles ranging from 28.0° to 74.7°, it is found that with the decrease of impact angle, the deformation degree of the droplet oscillation on the film surface increases. The results also indicate that the front spreading factor can increases by increasing impact velocity or by reducing the impact angle, whereas the back spreading factor increases with impact angle increasing. The impact velocity almost has no influence on it. The initial spreading velocity can increase by increasing the impact velocity and the impact angle.
Keywords： drop impact inclined liquid film spreading factor spreading velocity