Dynamics of supersonic spray combustion

The purpose of the work reported in this paper is to discuss the manner in which the models for momentum and thermal energy interaction between high enthalpy (supersonic) gas and initially subsonic liquid droplets in supersonic combustion models of a scramjet engine involving the evaporation of a hydrocarbon fuel differ from those for the analogous incompressible two-phase flows. Thus, many of the assumptions made in the case of low-speed flows are revisited in this paper for their validity for supersonic combustion involving liquid fuels. In some cases, simple scaling arguments are used to justify proposed simplifications of otherwise, complicated, general models. It is pointed out that these models are investigated outside of a CFD calculation of two-phase flows, to provide some baseline for evaluating their behaviors when they are actually used to simulate realistic supersonic two-phase flows. The problem of two-phase supersonic combustion has not received attention, and the present study aims to provide some preliminary fundamental understanding of the subject matter.