Computational study of the effect of cavity geometry on the supersonic mixing and combustion of ethylene

Abstract

In this numerical study, the supersonic combustion of ethylene in three model combustor configurations namely, baseline (no cavity), square cavity and inclined cavity are investigated. To this end, 3D, compressible, turbulent, non-reacting (with fuel injection) and reacting flow calculations using single step and 10-step chemical kinetics in conjunction with a one equation turbulence model have been carried out. In the mixing study, predictions of the flow features with fuel injection, fuel trajectories, contours of total pressure loss along the combustor are compared between the combustor models. In the combustion study, contours of heat release are compared across the combustor models. Overall performance metrics such as mixing efficiency, total pressure loss and combustion efficiency are also compared between the combustor models. The comparison of combustor top wall static pressure and exit total pressure predictions with experimental data reported in the literature are also presented and discussed. The results clearly show that the model combustor with a shallow and inclined aft wall cavity has the highest residence time and maximum heat release. In addition, the role of a smaller L/D ratio cavity is shown to be minimal on the predictions of residence time and the heat release.