Numerical investigation on the supersonic combustion of liquid kerosene in a dual-staged strut based scramjet combustor

In this study, a full-scale scramjet combustor with two-staged injection from Beihang University is numerically investigated. High enthalpy vitiated air is heated by the hydrogen-oxygen combustion at a total temperature of 1899K, entering the isolator entrance at a Mach number of 3.0. Two struts in the cross arrangement act as the main injectors, and a ramped-wall cavity, located downstream of the second strut, acts as the flameholder. The liquid kerosene acts as the fuel, and the whole fuel equivalence ratio is held constant to 1.0. The local fuel equivalence ratio at the first stage is varied from 0 to 0.7. Three-dimensional compressible, turbulent, reacting flow calculations with a single-step chemistry model are conducted using the FLUENT 12.1 code, which solves the Reynolds Averaged Navier Stokes (RANS) equations appropriate for calorically or thermally perfect gases with a cell-centered finite volume scheme. The Menter’s SST k-w turbulence model is used in this work. The static pressure profiles along the combustor side wall in different cases are presented. The axial variations of the combustion efficiency and total pressure losses are also calculated to investigate the influence of fuel distribution on the combustor performance. The numerical results show that the shock train induced by the first strut improves the kerosene-air mixing. After pressurized by the shock train, the inflow reaches a high static temperature to ignite the kerosene. With the local fuel equivalence ratio at the first strut increasing, the combustion efficiency and net thrust increase, while the mass-averaged total pressure recoveries at the combustor exit are nearly held constant. When the local fuel equivalence ratio at the first strut exceeds a certain value, the pre-combustion shock train is pushed out of the isolator, resulting in an inlet unstart. These numerical simulations can be applied to assist the design and analysis of the following experiments.