Computational simulation of scramjet combustors---a comparison between quasi-one dimensional and two-dimensional numerical simulations

1-D simulations based on the quasi-one-dimensional equations of fluid motion plus an ignition delay model and 2-D numerical simulations based on Reynolds-Averaged Navier-Stokes (RANS) equations have been performed for two different scramjet combustors. The combustor configurations at DLR and NASA's SCHOLAR Supersonic Combustor have been used as test cases for the 1-D and 2-D simulations. Comparisons between the published 3-D computational and experimental results and quasi-one-dimensional and 2-D simulations have been performed. The quasi-one dimensional modeling of NASA's SCHOLAR supersonic combustor captures the trends in Mach number, static pressure and static temperature for both cold flow and combustion case. The comparison with experimental result for combustion case reveals a close agreement with the pressure peak and the presence of an ignition delay. Thus, 1-D simulation very closely predicts the flow evolution within the combustor. On the other hand, for DLR supersonic combustor, due to the lack of oblique wave (i.e. shock waves and expansion waves) and shear dominated viscous flow simulation, 1-D model severely fails to predict the trend followed by the experimental result along the centerline of the combustor. However, the 1-D model is able to match the overall flow velocity achieved within the combustor downstream of the wedge at approximately six wedge chord lengths.