HEAT-TRANSFER AND FLUID-DYNAMICS DURING THE COLLISION OF A LIQUID DROPLET ON A SUBSTRATE .2. EXPERIMENTS

This paper presents an experimental study of liquid droplet impingemen t upon a substrate. Qualitative as well as quantitative comparisons we re conducted between the experimental measurements and the numerical p redictions from the theoretical model in part 1 of this paper. The dro plet deformation process was visualized using a two-reference-beam pul se holography method. Measurements of the transient splat radius were performed with a novel photoelectric technique. The experimentally obt ained droplet shapes were similar to the numerically predicted ones fo r the same conditions. The impact dynamics was characterized by drople t spreading, recoiling and oscillations. The spreading and recoiling m otions depended upon the initial velocity as well as the droplet prope rties. In summary, the theoretical predictions agreed well with the ex perimental results until the late stages of the droplet spreading proc ess. Copyright (C) 1996 Elsevier Science Ltd.