Radial Injector Mixing Effects on Detonation Zone Position in Rotating Detonation Engine

Abstract

Radial propellant injection in the annular combustion chamber of a rotating detonation engine (RDE), done in a manner to promote maximum size scale of vortices, has proven to be effective for gaseous propellants. Experiments with an RDE having a 154-mm-diameter annular combustion chamber have explored the dependence of detonation zone location on propellant mass flux using gaseous methane and oxygen. Computational fluid dynamic simulations of the non-reacting flows of these experiments estimate that the degree of propellant mixedness at the leading edge of the detonation zone must be between approximately 0.5 and 1.5 standard deviations from stoichiometric. This computational tool was also used to examine the mixing of gases that were radially injected into a smaller RDE having a 76-mm-diameter annular combustor. The smaller RDE is designed for parametric studies of injector configurations, which may or may not be configured for radial injection. The results of this study indicate that staggered radial injectors lead to more rapid mixing compared to impinging radial injectors in annular ducts and that decreasing mass flux reduces the mixing length.