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 impingement upon a substrate. Qualitative as well as quantitative comparisons were conducted between the experimental measurements and the numerical predictions from the theoretical model in part 1 of this paper. The droplet deformation process was visualized using a two-reference-beam pulse holography method. Measurements of the transient splat radius were performed with a novel photoelectric technique. The experimentally obtained droplet shapes were similar to the numerically predicted ones for the same conditions. The impact dynamics was characterized by droplet spreading, recoiling and oscillations. The spreading and recoiling motions depended upon the initial velocity as well as the droplet properties. In summary, the theoretical predictions agreed well with the experimental results until the late stages of the droplet spreading process. Copyright (C) 1996 Elsevier Science Ltd.