Effect of different strut design on the mixing performance of H2 fueled two-strut based scramjet combustor

Abstract

Strut fuel injection approach significantly influences the combustion mechanism inside the scramjet engines. To address this issue, researchers are nowadays mainly focused on a scramjet model with two struts. As the performance of the two-strut model is improved as compared to the original single-strut model as per the latest research findings, therefore the current research is focused on the impact of the different shapes of the two-strut on the combustion flow-field study of scramjet engines. Initially, experimental data from the already-published literature for a single strut is used to validate the implemented simulation techniques. Then, to investigate the combustion performance, different shapes of the two-strut are included in the already-existing DLR scramjet combustor. The SST k-ω turbulence model and steady RANS equations are used to carry out the numerical simulation. The semi-circular trailing edge half-wedge strut, with a combustion efficiency of roughly 92%, is the most effective strut configuration obtained in the current study. The findings also revealed that the semi-circular trailing edge half-wedge strut profile attains a stronger as well as a wider wake region, ensuring better combustion performance, and indicating that the two-strut model can be used as an efficient flame holder in subsequent works. Next, an analysis of how various inward fuel injection angles affect the performance of the optimum strut shape in terms of mixing efficiency and total pressure loss is provided. According to the study, an increase in the inward fuel injection angle significantly improves the mixing performance of the two-strut scramjet combustor. Additionally, the mixing and total pressure loss profiles reveal that the geometry with a 60° strut injection angle achieves early complete mixing within 0.145 m at the cost of only a slight increase in total pressure loss, and this outcome may lead to the development of a short-length supersonic combustor to minimize the drag forces and heat generation. Last but not the least, the optimal inward fuel injection angle (60°) of the two-strut and its effects on mixing performance under different freestream conditions are investigated, illustrating that mixing efficiency decreases with increasing Mach number in the same manner as single strut geometry.