Shock induced atomisation of a liquid metal droplet (2305.03525v1)

Abstract: The present study uses Galinstan as a test fluid to investigate the shock-induced aerobreakup of a liquid metal droplet in a high Weber number regime (We ~ 400 - 8000). Atomization dynamics is examined for three test environments: oxidizing (Galinstan-air), inert (Galinstan-nitrogen), and conventional fluids (DI water-air). Due to the readily oxidizing nature of liquid metals, their atomization in an industrial scale system is generally carried in inert atmosphere conditions. However, no previous study has considered gas-induced secondary atomization of liquid metals in inert conditions. Due to experimental challenges associated with molten metals, laboratory scale models are generally tested for conventional fluids like DI water, liquid fuels, etc. The translation of results obtained from conventional fluid to liquid metal atomization is rarely explored. Here a direct multi-scale spatial and temporal comparison is provided between the atomization dynamics of conventional fluid and liquid metals under oxidizing and inert conditions. The liquid metal droplet undergoes breakup through Shear-Induced Entrainment (SIE) mode for the studied range of Weber number values. The prevailing mechanism is explained based on the relative dominance of droplet deformation and KH wave formation. The study provides quantitative and qualitative similarities for the three test cases and explains the differences in morphology of fragmenting secondary droplets in the oxidizing test case (Galinstan-air) due to rapid oxidation of the fragmenting ligaments. A phenomenological framework is postulated for predicting the morphology of secondary droplets. The formation of flake-like secondary droplets in the Galinstan air test case is based on the oxidation rate of liquid metals and the properties of the oxide layer formed on the atomizing ligament surface.