  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.
