The supersonic combustion in three different combustors was numerically investigated by solving the compressible Navier-Stokes equations with implicit finite volume method.The results show that the cavity can change the waves in combustors

and facilitate the mixing of hydrogen and air for easier combustion. Besides

the relatively steady reversing area in cavity can be used to ignite and stabilize the flame;ejection of secondary hydrogen can neutralize the problems induced by injecting hydrogen only one time

and also improve the mixing and combustion of hydrogen and air

in despite of slightly larger total pressure loss.