Quasi-dual-mode behavior in the combustor of the HyShot scramjet

The flow in the HyShot scramjet combustor is studied using wall-modeled LES with a flamelet combustion model. The focus is on the qualitative changes in the flow structure as the fuel/air equivalence ratio (ER) is increased. For low ERs, an essentially linear pressure-rise is found, consistent with fully supersonic combustion. For higher ERs, a qualitatively different yet stable flow develops, with a stronger shock-train towards the end of the combustor. This shock-train is analogous to what occurs in the isolator in dual-mode operation, but is lodged within the region of heat release, with a position that depends on the ER; this is consistent with recent experimental data obtained by Laurence et al at the German Aerospace Center (DLR).