Abstract
The performance of gaseous hydrocarbon/air mixing in the inlet of a scramjet is investigated in this paper. The two-oblique-shock mixed-compression inlet configuration is selected, and cantilevered ramp injectors, designed to deliver rapid mixing in a high-enthalpy flow, are placed strategically near the leading edge of the inlet. Air inflow conditions correspond to a Mach 8 flight at a dynamic pressure of 67,032 Pa at a 28.6 km altitude. The objective of this study is to evaluate the impact of inlet geometrical parameters, fuel-injection properties, and injector dimensions on the mixing efficiency. Both light (CH 4 ) and heavy (C 12 H 24 ) hydrocarbon fuels are considered. The analysis ofthree-dimensional steady-state flowfields is undertaken numerically, using the WARP code. WARP solves the multispecies Favre-averaged Navier―Stokes equations, which are closed by the Wilcox t-ω turbulence model. The numerical results indicate that a mixing efficiency of up to 95.8% can be achieved with a low risk of premature ignition. Inlet compression ratio, fuel-tank stagnation temperature, and fuel/air equivalence ratio are all identified as having a significant influence on inlet fuel-injection performance. The applicability of the cantilevered ramp injector to the Mach 8 hydrocarbon inlet is validated and justified.
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