Numerical study of convective heat transfer of a supersonic combustor with varied inlet flow conditions

Characteristics of convective heat transfer of a supersonic model combustor with variable inlet flow conditions were studied by numerical simulation in this paper. The three-dimensional flow and wall heat flux at different air inlet Mach numbers of 2.2, 2.8 and 3.2 were studied numerically with Reynolds-averaged Navier–Stokes equations with a shear-stress transport (SST) k − ω turbulence model and a three-step reaction model. Meanwhile, ethylene was chosen as the fuel, and the fixed fuel-to-air equivalence ratio is 0.8 in all cases in this paper. The results of the simulations indicate that wall heat flux distribution of the combustor is very non-uniform with several peaks of wall heat flux at varied locations. For the low inlet Mach number of 2.2, a shock train structure is formed in the isolator, and three peaks of wall heat flux are located respectively on the backward face of the cavity, on the side wall near the fuel injection and on the bottom wall near the injection holes, and a maximum wall heat flux reaches 5.4 MW/m². For the medium inlet Mach number of 2.8, there exists a much shorter shock structure with three peaks of wall heat flux similar to that of Mach number 2.2. However, as the inlet Mach number increased to 3.2, there is no shock structure upstream of fuel injections, and the combustor flow is in a supersonic mode with different locations and values of wall heat flux peaks. The statistical results of wall heat loading show that the change of total wall heat is not monotonic with the increase of inlet Mach number, and the maximum appears in the case of Mach number being 2.8. Meanwhile, for all the cases, the bottom wall takes up more than 50% of the total heat loading.