Experimental investigation of the impact and freezing processes of a hot water droplet on an ice surface.

Water droplet freezing on an ice surface is a common phenomenon and poses hazards to a lot of applications, including wind turbines, aircraft, and power transmission lines. Since the water droplet temperature is critical, many studies have been carried out to understand the influence of the water droplet temperature on both the impact and freezing processes of droplets on different surfaces. However, the past research studies mainly focused on supercooled water droplets, not on hot water droplets. For applications such as hot-water ice-drilling, the understanding of freezing of hot water droplets on an ice surface is necessary. In the present study, we report the detailed dynamic motions of a hot water droplet impacting on an ice surface. The impact and freezing processes of the hot water droplet on the ice surface are recorded by two cameras. The effects of the water droplet temperature and the ice surface temperature on the impact and freezing processes of the water droplet were experimentally investigated. The results showed that, at the same ice surface temperature, the increase of the water droplet temperature resulted in the increase of the maximum spreading factor, the reduction of the height of the ice bead, and the slight increase of the freezing time. In addition, during the droplet spreading process, the experimental results of the normalized contact diameter fitted well with the exponential model and the water droplet temperature was found to have an apparent influence on the lamella thickness. [ABSTRACT FROM AUTHOR]