Interaction of Impact Liquid Drop With Splat in Spray Cooling

This study investigates the interaction between an impacting liquid drop and a splat generated on a solid prior to impact, focusing mainly on the wave production and propagation on the splat with low impact velocity. Using high-speed video, the wave generation concerning the effects of Weber number is observed and analyzed, including the first wave caused by drop kinematic energy, the secondary and tertiary capillary waves subjected to surface tension. Also, the wave propagation magnitude is discussed, the purpose of which is to provide a suitable method for predicting the wave diameter. Results show that the increasing of Weber number is slightly against the wave propagation, but this effect weakens gradually. The kinematic discontinuity theory devised for crown propagation can be applied to predict the wave propagation magnitude with an excellent agreement, for both the kinematic wave and the capillary wave. In addition, the propagation speed of the wave during the drop-splat interaction is also analyzed.