Effect of cavity back height on mixing efficiency of hydrogen multi-jets at supersonic combustion chamber

Stable fuel distribution and mixing is noteworthy for increasing the efficiency of the scramjet engine at high-speed flight. In this work, numerical studies are accomplished to inspect and disclose the effects of cavity back height on the fuel (hydrogen) spreading inside the cavity flameholder at supersonic flow. The effects of both positive and negative back height on fuel distribution are explained by analysis of the three-dimensional jet contour. The implications of multi-jets directions on the hydrogen distribution are also presented in this research. RANS equations with the SST turbulence model are employed for the computational investigations of 3-D supersonic air and fuel inside the cavity. Our outcomes show that the injection of the opposing multi-jets is more effective on fuel mixing when the back height is positive. However, multi hydrogen co-jet distributes the fuel jets homogenous inside the cavity for negative cavity back height. According to our results, the weakening the main circulation improves the mixing performance inside the cavity. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.