Hypervelocity fuel/air mixing in mixed-compression inlets of shcramjets

This paper investigates the mixing of hydrogen fuel with air in the mixing duct of a mixed-compression shock-induced combustion ramjet (sheramjet) inlet. Mixing augmentation through the use of cantilevered ramp injector arrays on opposite shcramjet inlet walls is studied and the influence of relative array locations is quantified. Studies were undertaken numerically using the WARP code that solves the Favre-averaged Navier-Stokes equations closed by the Wilcox k-omega turbulence model. Air-based mixing efficiencies of up to 0.58-0.68 were achieved with thrust potential losses less than that gained from high-speed fuel injection. Shocks created from the fuel injector structures play a major role in the mixing behavior of the fuel jets on the opposing side of the mixing duct. Chemically reacting studies verified for the correct selection of spanwise displacement of the fuel injectors, an air buffer created between the fuel and walls suppresses premature ignition while still allowing for a mixing efficiency of up to 0.46-0.54.