液滴低速撞击润湿球面现象观测分析

Observation and analysis of drop impact on wetted spherical surfaces with low velocity

采用高速摄像仪以10000帧/s的拍摄速度对液滴低速撞击润湿球体表面过程进行了实验观测,分析了液滴撞击后的反弹、局部反弹和铺展等现象,考察了黏度对撞击过程的影响;在此基础上,定量讨论了液滴铺展特征参数随撞击速度、球体直径和黏度的变化规律.观测发现:黏度较大且撞击速度较低时,撞击后可能出现反弹和局部反弹,黏度较小时则不发生;铺展面积随撞击速度的增大而增大;黏度增大时,铺展因子减小;在球体直径为4—20 mm范围内,随着球体直径的增加,铺展因子呈上升趋势.

The phenomenon of liquid drop impact on wetted spherical surfaces with low impact velocity is observed using a high speed digital camera at 10000 frames per second. Drop rebound, partial rebound and spreading are observed and analyzed, considering the effect of viscosity. Influences of the sphere diameter, impact velocity and viscosity on the spreading characteristic parameter are discussed quantitatively. The experimental observations show that the drop rebound and partial rebound phenomena may occur at large viscosity and low impact velocity, which cannot be observed at small viscosity. The spreading area can be increased by increasing impact velocity. The results also reveal that the spreading factor increases with viscosity decreasing. At the sphere diameters ranging from 4 mm to 20 mm, it is found that with the increase of the sphere diameter, the spreading factor will be increased.