Experiments on flame stabilization in a scramjet combustor with a rear-wall-expansion cavity

The current study investigated the characteristics of the flame stabilization in a hydrogen fueled scramjet combustor with a rear-wall-expansion cavity at the inflow condition of Mach 2.92 with stagnation pressure 2.6 MPa and stagnation temperature 1530 K. Effects of four representative fuel injection schemes on the combustion process had been compared. The experimental results show that the injection schemes with two parallel injectors (30 mm upstream the cavity) and with single injector (10 mm upstream the cavity) achieve slightly heat release increment when increasing the equivalence ratio. While the injection schemes with two cascaded injectors (30 mm and 10 mm upstream the cavity) and with two parallel injectors (10 mm upstream the cavity) would perform obviously more intense and stable combustion in the combustor at the same equivalence ratio. For the injection scheme with two cascaded injectors (30 mm and 10 mm upstream the cavity), although there would be less intense combustion above the cavity, there exist wider heat release zones downstream the cavity compared to the injection scheme with two parallel injectors (10 mm upstream the cavity). It is also demonstrated that the injection scheme with two cascaded injectors (30 mm and 10 mm upstream the cavity) is a favorable fuel injection scheme for the rear-wall-expansion cavity during the flame stabilization process, and a robust and stable flame would be achieved in the combustor.