Mixing and combustion characteristics in a cavity-based supersonic combustor with different injection schemes

Mixing and combustion characteristics in an ethylene fueled cavity-based scramjet combustor with different injection schemes are investigated experimentally and numerically in low equivalence ratio conditions, with inflow conditions of Ma = 2.52, stagnation pressure P-0 = 1.65 MPa and stagnation temperature T-0 = 1600 K. The wall-pressure distributions obtained by numerical simulations are in fairly good agreement with the experimental data. The numerical results also indicate that multiple-orifice cases have higher mixing efficiencies and combustion efficiencies than single-orifice cases. In addition, it is observed in the experiments that flamebases are not stabilized in a fixed position. In single-orifice cases, the flamebases oscillate dramatically between the cavity leading edge and trailing edge, and the oscillations are similar for different injection pressures. In multiple-orifice cases, the flamebases oscillate slightly in the cavity shear layer just downstream of the leading edge and the amplitudes with lower injection pressure are larger than those with higher injection pressure.