Investigating the combustion-flow coupling effects in a cavity-based scramjet combustor

This study investigates combustion-flow interactions within a scramjet combustor, examining how varying fuel equivalence ratios influence flow characteristics and combustion performance. By employing numerical simulations and experimental validations, we explore the dynamic interplay between combustion flames, shock waves, and localized flow fields, aiming to elucidate the evolution laws governing flow dynamics and flame propagation. The findings reveal that the recirculation zone within the cavity undergoes continuous disassembly and merging, inducing periodic oscillations in the flow field with a cycle duration of 3.6 ± 0.2 ms. Hydrogen injection stabilizes the flow field by balancing upstream and downstream pressures, thereby creating a structured mixing flow field. Furthermore, under reacting flow conditions, a pre-combustion shock train forms due to the combined effects of heat release from combustion and compression caused by fuel injection. Notably, at a fuel equivalence ratio of 0.398, reducing hydrogen supply causes a shift in the combustion regime, accompanied by decreased heat release and weakened shock train intensity. The specific impulse reaches its maximum at a ratio of 0.453, while flow uniformity at the combustor exit is optimized at 0.496. This study contributes to the understanding of complex combustion-flow interactions in scramjet engines, offering valuable insights into optimizing engine performance.