The supersonic combustion experiments are carried out using T3 free-piston shock tunnel. Different shock tube fill pressures have various inflow conditions. $15^{circ}$ inclined hydrogen fuel injection is located before the cavity. Oblique shock is generated from the cavity and reflects off the top and bottom wall. For non-reacting flow, fuel makes the shear layer thicker above the cavity therefore, the shock is generated just before the trailing edge. This research has self-ignition in the combustor. For reacting flow, as the equivalence ratio increases, flame starts to generate near the injector or occur in the recirculation zone before the injector. High fuel injection sustains the jet shape in the cross flow and air can mix with fuel along the shear layer. Therefore, two flame layers find above the cavity for high equivalence ratio.