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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.

This work is relevant to numerical simulation of atmospheric entry phase of space missions and in high enthalpy facilities producting flow conditions close to flight conditions. Such flows are featured by low pressure and high temperature, which induces thermal and chemical nonequilibrium, while calculations with equilibrium assumption give both qualitative and quantitative errors.

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