Verification and characteristics of continuous rotating detonation waves in a novel rounded-rectangle hollow combustor

A noncircular cross-sectioned combustor holds the potential to facilitate the flexible design of continuous rotating detonation (CRD) engines, meeting the demands of airframe/engine integration. In this study, we propose and validate a novel rounded-rectangle hollow combustor comprising arc and straight segments. We conduct experimental and numerical investigations into the detailed propagation and combustion characteristics of the CRD wave in this combustor. The results demonstrate that a single hydrogen-air CRD wave can be achieved and sustained over a wide equivalence ratio (ER) range. As the ER increases from 0.71 to 1.25, the CRD wave's propagation velocity escalates from 1837.1 to 2190.8 m/s, with a substantial decrease in the relative standard deviation from 9.76% to 0.85%. The curvature variation along the combustor circumference influences the local propagation velocity, combustion intensity, shock wave strength, and shock wave system. Specifically, the constraints imposed by the arc segment significantly enhance combustion intensity and amplify shock wave strength. This is evident through a higher heat release rate fraction (f_HRR), increased pressure peaks, and elevated propagation velocity. At the straight segment, the shock wave system comprises the CRD wave, leading, and trailing diffracted shock waves. However, the constraint from the arc segment leads to the formation of an additional reflected shock wave, altering the shock wave system to include the CRD wave, the reflected shock wave, and the leading diffracted shock wave. Thus, this study advances our understanding of CRD characteristics in noncircular cross-sectioned combustors, providing insight to the design theory for CRD engine combustors.