Numerical Study of Counter-Rotating Wave Propagation in a Rotating Detonation Engine

The phenomena driving counter-rotating wave (CRW) mode formation in rotating detonation engines (RDEs) are relatively unexplored in the literature. Therefore, a full-scale 3D non-premixed reacting flow simulation was performed to simulate CRW mode propagation in a hydrogen-air RDE. This study investigates the flow field and wave dynamics within the combustor due to the presence of CRWs in the system. The pressure, heat release and fuel-air composition in the presence of the CRWs were analyzed and the injector response to the detonation wave passage was quantified. The CRW formation involved several detonation wave and weak shock wave collisions, and ignition of premixed hot spots by reflected shock waves. The CRWs formed localized high pressure and heat release regions upon collision. Post-collision, weakening of the detonation waves was observed. The periodic injector blockage and recovery due to the passage of multiple detonation waves can led to a stratified fuel-oxidizer composition within the combustor. This stratification produced significant deflagrative combustion. The deflagrative combustion regimes, i.e., parasitic combustion and commensal combustion, became prominent upon moving radially inward from the outer to the inner wall. More than 60 % of the total heat release in the combustor occurred in fuel-lean regions and > 80 % of heat release occurred in regions below a pressure of 5 bar. These deflagrative combustion regions are detrimental to the overall detonation efficiency of the combustor.