A Study on the Behavior of a Droplet Impacting onto a Heated Surface

고온 벽면과 충돌하는 단일 액적의 거동에 관한 연구

In this paper an experimental study is presented of the problem of dynamic behavior of a water droplet impinging upon a heated surface. The experiments are mainly focused on the effects of impinging angle of a droplet and surface temperature on the impact dynamics of the droplet. It Is clarified that the droplet exhibits much different behavior depending on the normal momentum of an impinging droplet before impact. At surface temperature In the nucleate boiling regime. the disintegration of a droplet doesn't occur, whereas the deforming droplet adheres to the surface. The spreading and contraction of the liquid film is repeated a couple of times for the horizontal surface but the expanded droplet just slips without noticeable contraction for the inclined surfaces. In the film boiling regime, the impinging droplet spreads over the surface as a liquid film which is separated from the surface by produced vapor. Depending on the magnitude of the normal momentum of the droplet the disintegration into the several irregular shapes of liquid elements occurs for the horizontal and 30o-inclined surfaces, whereas the impinging droplet for the 60o-inclined surface doesn't break up and tends to recover the original spherical shape.