Inlet fuel injection in a mach 12 shape-transitioning scramjet

Abstract

A Rectangular-to-Elliptical Shape Transitioning (REST) scramjet inlet designed for fight at Mach 12 was simulated with and without hydrogen fuel injection along the body-side compression surface, to investigate the feasibility of inlet injection in a practical scramjet configuration. The observed flowfields show that at an equivalence ratio of 0.3, the fuel jets cannot escape the body-side boundary layer, and have little effect on inlet flow structures. Because of this turbulent boundary layer, fuel mixing efficiency is greater than 80% by the end of the inlet. Combustion is observed in the near-constant area section near the end of the inlet, with a fuel-based combustion efficiency of 52%. Inlet drag increased less than 6%, showing that inlet fuelling provides efficient mixing and combustion on the body side of the engine, thermal compression of the remaining flow, and provides a pilot for fuel injected further downstream, without significantly increasing engine losses