Experimental investigation of airflow-assisted water droplet impact on horizontal solid surface

Abstract

In the practice of aircraft icing, airflow-assisted droplet impact is a significant process that needs special attention and further study. In this research, airflow-assisted water droplet impact on a horizontal solid surface is studied experimentally. Effects of the airflow velocity and the droplet release height on the dynamic behaviors of the droplet, including the deformation rate in the airflow, the wetting factor on the surface and the duration of different stages, are analyzed and discussed. Seven kinds of airflow-assisted water droplet impact modes are observed and a regime map is drawn to distinguish the boundary of each mode. The results show that the airflow velocity plays a crucial role in affecting dynamics of the droplet. In the “no breakup - impact” regime, the maximum horizontal deformation rate increases monotonously with the initial gaseous Weber number Weg. Besides, both the maximum and the equilibrium wetting factor keep growing with the increase of Weg. The airflow significantly suppresses retraction of the droplet. In the “breakup - impact” regime, the maximum wetting factor declines slightly with the increasing Weg. This study is significant for understanding the microphysical mechanism inside the airflow-assisted water droplet impact phenomenon.