Aerobreakup of liquid metal droplet*

The aerobreakup of liquid metal has application in metal powder production, thermal spray coatings, explosive detonations, metalized propellant combustion, and liquid metal cooling systems. Liquid metals provide several challenges which differ from other common Newtonian liquids (like water, ethanol, and liquid fuels). The applicability of the results obtained from the aerobreakup of common liquids to the atomization of liquid metals is a marginally explored area and is the focus of the present work. Conventional fluids and liquid metals significantly differ in density, surface tension, and viscosities. Further, liquid metal exhibits properties such as surface oxidation, which are not observed in conventional fluid experiments. Here we use a liquid metal alloy (Galinstan) as a viable material, and the aerobreakup results are compared with Newtonian fluids (water and glycerol-water solution). The surface tension of chosen material is 10 times that of water, while its viscosity is ~ 2.4 times that of water. A similar range of Weber number (We) values is tested for Galinstan and Newtonian counterparts, and the focus was kept on understanding the role of surface oxidation on the atomization characteristics. Retardation in the breakup characteristics is observed for liquid metal droplets where a lesser number of secondary droplets (in comparison to Newtonian fluids) with irregular shape are formed. However, for the considered values, a similar breakup mode (Shear-induced entrainment (SIE)) is observed for the Galinstan and Newtonian droplets.