Methodology and Analysis for Determination of Propagation Speed of High-Speed Propulsion Devices

This study describes a methodology and gives an example of a simplified analysis to determine the steady propagation speed of a projectile fired into a gaseous mixture of fuel and oxidizer. For tractability, the steady supersonic flow of an inviscid calorically perfect ideal reacting gas with high activation energy over a symmetric double wedge, unconfined by a cowl, is considered. A search of parameter space reveals propagation speeds which give rise to shocks of such strength which induce a flame sheet to be at a location which allows the combustion-induced thrust to balance the wave drag. For a fixed heat release greater than a critical value, two steady propagation speeds are predicted. The solution at the higher Mach number is stable to quasi-static perturbations while the solution at the lower Mach number is unstable. This methodology is that which should be applied to analyze devices which have more complex geometries such as the ram accelerator or oblique detonation wave engine.