Partially premixed flamelet modeling in a hydrogen-fueled supersonic combustor

In scramjet combustors, the combustion process is usually partially premixed, that is, both the non-premixed and the premixed regimes should be taken into account. Based on the multi-regime flamelet (MRF) model proposed for low Mach number flows, a modified MRF model that applies to supersonic flow conditions has been developed. Taken a hydrogen-fueled model combustor as test case, the good agreement between the calculation and experiments was obtained. The distribution of weighting coefficient, which is defined based on the concept of combustion regime index, shows that the flow field in the supersonic combustor is partially-premixed. The premixed regime distributes in the backflow region, the shear layer and the boundary layer. Comparisons between the results of steady laminar flamelet (SLF) model and the modified MRF model show that the latter one gives a more precise prediction of temperature profiles, indicating the modified MRF model has better versatility and accuracy.