Collision dynamics of a single water droplet impinging on a high-temperature pool of oil

The article presents the dynamic process of a single water droplet impinging on a hot oil surface with various temperatures ranging from 205 to 260 ${}^{\circ }\text{C}$. Distilled water is used to produce water droplets with different diameters. The impact behavior is recorded by using a high-speed digital camera with the speed of 2000 fps. The result shows that two typical phenomena, including crater–jet–bubble and vapor explosion, can be observed. The vapor explosion occurs when the oil temperature is higher than 210 ${}^{\circ }\text{C}$. The oil temperature, the droplet size, and the Weber number are found to have significant influence on the vapor explosion time. The higher the oil pool temperature is, the earlier the vapor explosion occurs. Vapor explosion time increases with the droplet size, while decreases as the droplet Weber number increases. Moreover, the maximum heat absorption for a single water droplet immersing into the hot oil is calculated considering the changes of the droplet size. Both dimensionless maximum crater depth and maximum jet height increase with the pool temperature due to the surface tension, viscous force and decreasing density of the hot oil.