A new Eulerian Multi-Fluid model for bi-component polydisperse sprays: An essential approach to evaluate the impact of aluminum combustion on solid rocket motor instabilities

In solid rocket motors, the distributed combustion of aluminum droplets is suspected to be a driving mechanism of hydrodynamic and thermoacoustic instabilities. The accurate simulation of evaporating bi-component polydisperse sprays, strongly coupled to unsteady gaseous flows, appears as a determining step for future solid rocket motor optimization. In this contribution, we propose a new Eulerian Multi-Fluid to model reactive bi-component sprays that has been designed to follow accurately the evolution of the composition and the complex thermodynamics of the droplets. The objective of this work is twofold. The first one consists in the derivation of this new Multi-Fluid model and its hypotheses, and the way it is conditioned by the droplet composition. Then we present a time splitting integration strategy particularly efficient to deal with unsteady two-phase flow computations.