MODELING OF WATER DROP IMPACTIONS IN THE LEIDENFROST REGIME

Experiments of monosized water drop train impingement on a surface heated well above the Leiden-frost temperature are used to derive empirical and semi empirical models describing the dynamics of the reemited drops for the general case of non-normal impacts. The experimental setup combines shadowgraphy with high-speed imaging to obtain both the size and trajectories of the reemited drops. The obtained data are analyzed to describe the impact dynamics and the properties of the reemited drops: contact time, maximum spread diameter and reemited velocities for the rebound regime, drop diameter and velocity distributions in the splashing regime. In the rebound regime, good agreement of the present experimental data with theoretical predictions of the literature based on a mechanical spring-mass analogy is observed. In the splashing regime, the arithmetic drop diameter distribution appears to evolve from a multimodal distribution at the rebound splashing threshold towards a single mode distribution. For both the rebound and splashing regimes, the initial velocity component tangential to the impinged surface is damped proportionally to the normal Weber number. In the splashing regime, the average velocity of the reemited drops normal to the surface appears almost independent of the normal impact Weber number when normalized by its initial value.