Combustion in a solid fuel scramjet with channel geometry variation due to burnout

Abstract

Stability of combustion in solid fuel scramjets is contingent upon proper geometry of fuel grain and availability of a flame holder. Flame stabilization is achieved in the recirculation zone developing due to sudden expansion behind the inlet. Previous experimental and theoretical works suggest that there exists an optimum range of length-to-diameter ratios for the flame holder. However, due to fuel burnout the channel and flame holder geometry change in the process of scramjet operation, the regression rate being variable both in time and length. The purpose of this work is to develop a computational model of a solid-fuel scramjet taking into account the geometry variation, as well as to obtain typical flow patterns at the different stages of combustion. The numerical model is based on a system of fully compressible RANS equations with k-epsilon turbulence model. Turbulent combustion is described by the Eddy Dissipation Concept (EDC) model.Stability of combustion in solid fuel scramjets is contingent upon proper geometry of fuel grain and availability of a flame holder. Flame stabilization is achieved in the recirculation zone developing due to sudden expansion behind the inlet. Previous experimental and theoretical works suggest that there exists an optimum range of length-to-diameter ratios for the flame holder. However, due to fuel burnout the channel and flame holder geometry change in the process of scramjet operation, the regression rate being variable both in time and length. The purpose of this work is to develop a computational model of a solid-fuel scramjet taking into account the geometry variation, as well as to obtain typical flow patterns at the different stages of combustion. The numerical model is based on a system of fully compressible RANS equations with k-epsilon turbulence model. Turbulent combustion is described by the Eddy Dissipation Concept (EDC) model.