Diagnostic Investigation of Flow field Characteristics of Cavity based Scramjet Combustors

In this paper diagnostic investigation of flow field characteristics of different cavity based scramjet combustors have been carried out for both non-reacting and reacting flows. The hydrogen fuel is injected at three different jet angles from ten different locations for the optimization of its location and jet orientation. The numerical studies have been carried out using a validated 2D unsteady, density based 1st-order implicit shear stress transport k-ω turbulence model with multi-component finite rate reacting species. The results show a wide variety of flow features resulting from the interactions between the injector flows, shock waves, boundary layers, and cavity flows. We conjectured that an optimized cavity is a good choice to stabilize the flame in the hypersonic flow as it generates a recirculation zone in the scramjet combustor. We comprehended that the cavity based scramjet combustors having a bearing on the source of disturbance for the transverse jet oscillation, fuel/air mixing enhancement, and flame-holding improvement. We concluded that cavity shape with backward facing step and 45 forward ramp is a good choice to get higher temperatures at the exit compared to other four models of scramjet combustors considered in this study. Additionaly, we inferred that fixing the fuel injector at an angle of 45 towards the inlet flow at a longitudinal distance 1.4 times of the inlet diameter of the combustor from the head-end could improve the combustor efficiency.