Effect of Oxygen Enrichment in High Mach Number Scramjet Inlets

Abstract: Oxygen enrichment is the mixing of small amounts of pure O2 into the fuel of an airbreathing propulsion system, with the goal of improving ignition behavior in adverse conditions. This work considers simulations of oxygen enrichment in a Mach 12 shape-transitioning supersonic inlet, part of a hypothetical three-stage airbreathing launch system for placing satellites in orbit. Three-dimensional reacting numerical simulations of the flowpath are undertaken, with detailed chemical kinetics and Reynolds-Averaged turbulence modeling. The simulations find no major negative consequences of enrichment and suggest that the extra O2 notably improves combustion conditions at the end of the inlet. These results imply that oxygen enrichment may be capable of extending the operating envelope of airbreathing propulsion systems to higher altitudes and faster velocities and may improve their prospects for revolutionizing access-to-space. Keywords: Computational Fluid Dynamics, Aerospace Propulsion, Hypersonics