An unstructured RANS/flamelet CFD solver for numerical simulation of the supersonic combustion in an integrated ARI/GP scramjet combustor

In this paper, a parallel finite volume RANS/Flamelet CFD solver is developed for supersonic turbulent combustion simulation. The computational domain is meshed with unstructured polyhedral cell, i.e., a mesh element can be tetrahedron, wedge, pyramid or hexahedron in the grid system for 3D case. The implicit LU-SGS algorithm is adopted as the time integration method. The convective fluxes are computed with the HLLC approximate Riemann solver. The states at the cell faces are reconstructed with a second-order interpolation in conjunction with Barth's slope limiters. The turbulence model equations and flamelet table index scalar equations are solved in sequence at each time step of the LUSGS integration of RANS equations. Menter's SST k-ω turbulence model is implemented. Interaction between turbulence and chemistry is accounted for with the assumed β-PDF model. The flamelet table is constructed using the FlameMaster 3.9 code by Pitsh. To account for the compressibility affects, Overmann's method is adopted, that is, only the species mass fraction in the flamelet table are used, and temperature is computed from the total energy directly. The solver is used to simulate the supersonic combustion in the DLR scramjet, and good agreements were obtained between the numerical results and the experiment ones. Then the solver is further used to simulate the ethylene (C ₂H ₄) fueled ARI/GP scramjet combustion. The ARI/GP scramjet combustor consists of an aero-ramp injector and a gas-portfire igniter. Several experiments had been conducted in the supersonic wind tunnel in BUAA, formally. Computed wall pressure is in good agreement with those of the experiments. The research demonstrates that the unstructured RANS/Flamelet solver is suitable for supersonic combustion simulation.