Collision Dynamics of a Water Droplet Impinging on a Rigid Surface above the Leidenfrost Temperature.

Abstract

The collision dynamics of a water droplet impinging on a rigid surface abovethe Leidenfrost temperature aro described from an experimental point of view. Emphasis is placed upon the col[ision of relatively small droplets in the range from 300 to 600um with the surface. The surface temperature is fixed at 500'C. The first purpose of the present study is to examine whether or not the prior empirical rules obtained by using droplets of 2 to 3 mm give an app[icability to the case where the droplet size is much smaller. The second is to clarify the relation between the Webernumberand the coefficient of restitution, when the droplet rebounds from the hot surface without disintegrating into a number of particles. Also, the maximum value of the diameter of droplet which can spread on the surface and the resident time are examinedand discussed by comparing the result obtained here with the prior empirical formulae proposed by a few researchers.