The study investigated the influence of fuel injection position in a supersonic reacting flow environment inside a bottom wall cavity. To understand the flow mechanics in supersonic combustion, a numerical analysis has been performed using the Reynolds-averaged Navier–Stokes (RANS) equations combined with the shear stress transport (SST) k-ω turbulence model. Shock patterns, along with pressure and temperature variations throughout the combustor, have been analyzed. The computational technique can be applied to further research as the computational findings are within a reasonable range and are corroborated by experimental evidence. Unlike the DLR scramjet, adding fuel injectors in the cavity increases wall pressure owing to the intensified shock wave production at the cavity’s edges, which in turn amplifies the total pressure loss of the combustor.