Implication of geometrical configuration of cavity on combustion performance in a strut-based scramjet combustor

The present work describes the numerical investigation on the implication of the geometrical configuration of a cavity with a strut-based scramjet combustor. Firstly, the combustion characteristics of a combustor with a cavity and the combustor without a cavity are compared and evaluated to portray the effect of a cavity. On the other hand, a separate study is performed to investigate the interplay of cavity parameters namely, length to depth (L/D) ratio of a cavity and angle of a cavity (alpha) on the performance of a strut-based scramjet combustor. Our study reveals the formation of a strong recirculation zone in the cavity region which improves the mixing and combustion efficiency in the case of a cavity-based combustor. It is observed that the combustion commences relatively earlier in the case of a cavity-based combustor and reaches to its peak value of around 80%. Further, the size of a recirculation region depends on the distance between the strut injector and the length of a cavity. Moreover, the shear layer is observed in the cavity region inducing a weak shock at the trailing edge of a cavity which deteriorates the performance of a scramjet combustor particularly for a higher angle of a cavity(a) and lowers L/D ratio of a cavity. Also, the combustion efficiency is found to be optimal with moderate pressure losses at L/D = 4 and alpha = 30(0).