The effect of fine evaporating droplets on the adiabatic-wall temperature in a compressible two-phase boundary layer

Abstract

A steady-state supersonic flow of a viscous heat-conducting gas with an admixture of small droplets over a flat plate is considered. The plate surface is assumed to be thermally insulated, and its equilibrium temperature is greater than the evaporation point of the droplets. In contrast to previous publications, the case of low-inertia droplets, which do not deposit onto the wall and have time to evaporate in the boundary layer, is considered. Within the two-fluid approximation for the laminar gasdroplet boundary layer with a compressible carrier phase, a parametric numerical study of the effect of evaporating droplets on the boundary layer structure and the temperature of the adiabatic wall is performed. The similarity parameters are found and the range of these parameters is determined, in which the adiabatic-wall temperature is reduced substantially due to the droplet evaporation even for very low initial concentrations of the liquid phase. This makes promising the use of the condensed phase in the schemes of gasdynamic energy separation based on heat transfer between the flows in subsonic and supersonic boundary layers.