Fluidics of an immiscible drop impact onto a hot oil film

Droplet rapid phase transition during its impact over a hot immiscible oil film is studied experimentally, which is of paramount importance in fire extinguishing, forensics, internal combustion engines, and various accident scenarios in the industries. The impact of a cold methanol droplet on a hot mustard oil film and its repercussions are analyzed from high-speed images for a temperature range relevant from the thermodynamic and heat transfer perspective. The interfacial temperature of the hot oil film has been varied through the saturation temperature, Leidenfrost point, superheat limit, and critical temperature, for methanol. A regime map has been proposed to characterize fluidic observations on Weber number and non-dimensional average temperature plane. Violent cavity crater explosions have been observed above a critical Weber number ranging 70-80 for average interfacial temperature higher than the critical point of methanol due to direct contact between the droplet and base of the petridish.

Automated summary

This experimental study investigates the rapid phase transition of a droplet during its impact on a hot immiscible oil film, which is crucial in fields such as fire extinguishing, forensics, internal combustion engines, and accident scenarios in industries. The impact of a cold methanol droplet on a hot mustard oil film and its consequences are observed and analyzed. The study proposes a regime map to characterize the observations based on Weber number and non-dimensional average temperature. It also identifies violent cavity crater explosions above a critical Weber number for high average interfacial temperature.