Impact behaviors of a millimetric impinging drop on a superheated Al alloy surface

The impact behaviors and boiling regimes of millimetric water droplets on an aluminum alloy are experimentally investigated with varying surface temperatures. Compared to the impact on the unheated surface, different impact phenomena are observed on the superheated surface, suggesting the existence of a vapor layer underneath the drop. The dynamic Leidenfrost point (at which the film boiling and contact boiling regimes are differentiated) is revealed, which is dependent on the Weber number. In addition, the spreading characteristic is estimated in terms of the maximum spreading diameter. The growth of the maximum spreading diameter and its dependency on the Weber number on the superheated surface are clearly identified and compared with the scaling law in the previous studies.