An Experimental and Theoretical Investigation of Rotating Detonation Rocket Engine Wave Dynamics

Abstract

Rotating detonation rocket engines (RDREs) have combustion chamber geometries that are inherently susceptible to tangential combustion instabilities. Low-amplitude pressure oscillations in the combustion chamber couple with the heat release process, resulting in high-amplitude combustion instabilities. In RDREs, this process induces a deflagration to detonation (DDT) transition. The detonation waves travel around the annulus at speeds between the hot gas speed of sound and the Chapman-Jouguet (CJ) velocity. To better understand the detonation wave dynamics, linear acoustic theory was applied to the RDRE combustion chamber. A correlation between the fundamental frequencies of the detonation waves and the natural acoustic frequencies of the combustion chambers was found. A combustion chamber linear acoustic model (CCLAM) was developed relating the wave speed and number of waves to the combustion chambers' acoustic modes through the oblique shock angle. Measurements taken of the oblique shock angles support the theory.