The effects of top and bottom wall divergence on the supersonic combustion of the ethylene jet in a pylon-cavity configuration were studied numerically. The free-stream flight condition of Mach number 5 at an altitude of 25 km was considered, and the isolator inlet conditions were obtained using a two-dimensional inlet simulation. The equivalence ratios of 0.15 and 0.30 were considered for this study. A steady Reynolds-Averaged Navier-Stokes equation set with species transport was used in this study. The cubic K- \(\epsilon \) turbulence model with variable turbulent Schmidt number was used. The validation of the equation set was performed using experimental data from the literature. The simulation results indicate that the type of divergence and equivalence ratio affects the flow structures and reaction zones. The top wall divergence configuration produced better combustion efficiency than the bottom wall divergence configuration at both equivalence ratios. The mass-averaged total temperature also suggested the better heat addition of top wall divergence than the bottom wall divergence. Even the bottom wall divergence at a high equivalence ratio showed less effectiveness till x/dj = 30 when compared to the low equivalence ratio cases. The total pressure loss was higher for the top wall divergence than the bottom wall divergence at their respective equivalence ratios. However, the difference in total pressure loss started to appear after x/d \(_j\) = 30 at a low equivalence ratio, whereas it started after x/d \(_j\) = 10 at a high equivalence ratio.