Aerobreakup of a liquid metal droplet

The current investigation employs Galinstan as the test fluid to explore the gas induced breakup phenomenon of a liquid metal droplet under high Weber number conditions (We ~ 400 - 8000). Three distinct test environments are considered: oxidizing (Galinstan-air), inert (Galinstan-nitrogen), and conventional fluids (DI water-air). In industrial setups, liquid metal atomization usually takes place in inert atmospheres due to their propensity for oxidation. Surprisingly, no previous research has focused on the gas-induced secondary atomization of liquid metals under inert conditions. Typically, laboratory-scale models employ conventional fluids like DI water or liquid fuels to address the challenges related to molten metals. However, there is a need for studies investigating the transferability of results from conventional fluids to liquid metal atomization.

In this study, a comprehensive comparison is made between the atomization dynamics of conventional fluids and liquid metals under oxidizing and inert conditions on different spatial and temporal scales. The liquid metal droplet experiences breakup through the Shear-Induced Entrainment (SIE) mode within the examined range of Weber numbers. The mechanism governing this breakup is elucidated by considering the relative dominance of droplet deformation and KH wave formation. Notably, the research presents quantitative and qualitative similarities among the three test cases while highlighting the distinctions in the morphology of fragmenting secondary droplets in the oxidizing test case (Galinstan-air) due to the rapid oxidation of the fragmenting ligaments. Additionally, a phenomenological framework is proposed for predicting the morphology of secondary droplets. The unique formation of flake-like secondary droplets observed in the Galinstan-air test case is attributed to the oxidation rate of liquid metals and the properties of the oxide layer formed on the atomizing ligament surface.