Variation of inlet boundary conditions on the combustion characteristics of a typical cavity-based scramjet combustor

Abstract

The influences of wall functions, reaction model, and wall Prandtl number on the reacting flow field characteristics of a typical cavity-based scramjet combustor have been investigated numerically, and the computed results have been compared with the available experimental data in the open literature. The computed results are in reasonable agreement with the experimental data, but the pressure downstream of the leading edge of the cavity is overpredicted. Meanwhile, the grid discrepancy has been analyzed by employing three different grid scales, namely the coarse, the moderate, and the refined grids. The obtained results show that the moderate grid may be employed with confidence to compute the reacting flow field of the scramjet combustor. The wall functions, reaction model, and wall Prandtl number have a large impact on the pressure distribution along the floor face of the cavity, and this may be due to the influence of the variance of the flow separation point on the top wall for the different cases investigated with different inlet boundary conditions. The static pressure along the floor face of the cavity decreases with an increase in the wall Prandtl number, and then increases when the wall Prandtl number is large enough, namely 1.2 in the current study. This points out that there exists an optimal wall Prandtl number for the prediction of the reacting flow field of the cavity-based scramjet combustor.