Development of a Shell-Flaking Model for Hydriding Ejecta Particles

Recent experiments performed at Los Alamos National Laboratory have shown that metal particles ejected from a shocked surface show vastly different behavior when the accepting medium is either inert or reactive. Particles which are ejected into an inert medium appear to breakup in a standard liquid droplet breakup mechanism. However, those ejected into the reactive, hydrogen-based media form a hydride shell and exhibit a non-monotonic velocity response in recorded LDV data. The physical processes which dictate this phenomenon are mostly unknown and are of interest for accurate modeling of the trajectories of the ejecta after formation. Point-particle simulations of the inert experiments are performed to validate the currently implemented ejecta sourcing and transport models of the hydrocode to be used for further model development and testing. Then, validation of a numerical solver for the inner and outer radii of the growing hydride shell around the ejecta due to chemical reactions with the ambient gas against experimental data is also shown for single particle cases. Finally, the ongoing development of a model meant to simulate shedding of small particles from the hydride shell formed around the reacting ejecta particles as they propagate through the gas is discussed.