Coupling Effect of Multicavity on Flame Stabilization Mode Transitions in Scramjet Combustor

To investigate the effect of the multicavity on flame stabilization mode transition in a scramjet combustor, experiments involving various fuel injection strategies were conducted in a direct-connect supersonic combustor with a multicavity at the entrance with a Mach number of 3.0. The flame stabilization mode of the first cavity transitioned under all working conditions, but the equivalence ratio and wall static pressure changes were different. According to the different driving modes, the transition types were identified to be direct-driven local heat release and indirect-driven downstream backpressure. Direct changes in the local equivalence ratio could lead to significant combustion variations. The difference in combustion intensity between the two flame stabilization modes resulted in obvious path dependence, and the different transition paths of the flame stabilization mode could yield a difference in the equivalence ratio of ?f=0.10 at the moment of flame stabilization mode transition. If the equivalence ratio of the first cavity was set to a low value, the backpressure generated by downstream combustion was indirectly employed to promote the flame stabilization mode transition of the first cavity, which could reduce the degree of abrupt change. In addition, different transition paths could generate a difference in the equivalence ratio of ?f=0.03 at the moment of flame stabilization mode transition.