Propagation and heat release characteristics of rotating detonation in a ramjet engine with a divergent combustor

Three-dimensional numerical simulations with detailed chemistry were conducted on a rotating detonation ramjet engine (RDRE) fueled by ethylene. The study compared the basic structure, combustion characteristics, and performance of the rotating detonation wave (RDW) between isometric and divergent combustors with varying divergent angles. The results reveal that the RDW propagates with a slight inclination relative to the circumferential direction in the divergent combustor, whereas it propagates with a larger inclination in the isometric combustor. The resultant velocity perpendicular to the RDW in the divergent combustor exceeds that in the isometric combustor and remains consistent across different divergent angles. Furthermore, the inclination angle adapts to variations in incoming flow velocity. In the divergent combustor, the incoming flow accelerates, depressurizes, and exhibits a lower static temperature, significantly suppressing the parasitic combustion caused by backward pressure perturbations. Additionally, the divergent combustor minimizes non-ideal heat release in the recirculation zone near the ramp corner. Consequently, the proportion of ethylene consumption associated with high heat release rates in the divergent combustor is significantly higher than in the isometric combustor. The suppression of parasitic combustion also enhances RDW propagation stability in the divergent combustor. Notably, the total pressure loss in the divergent combustor is reduced by 7.25% at the outlet compared to the isometric combustor, attributed to the absence of a recirculation zone at the ramp corner. These findings provide valuable insights for the design and optimization of RDRE configurations.