Propagation characteristics of hydrogen-air rotating detonation wave in disk-shaped combustors with different configurations

Experiments are performed to investigate the propagating characteristics of rotating detonation fueled by hydrogen in disk-shaped combustors with different configurations. Three combustor configurations are employed in the experiments, and the channel convergence ratio is ranged from 1.0 to 2.61. The mass flow rate varies from 50 to 450 g/s, and the equivalence ratio is ranged from 0.4 to 2.75. The operation maps including single-wave, symmetric dual-wave, asymmetric dual-wave and triple-wave rotating detonation mode are plotted in this study. The results indicate that the propagation process of rotating detonation wave is more stable when the combustor channel area remains constant. Engine exit convergence is beneficial to increase the intensity of rotating detonation wave and detonation-wave parameters, but "two-plane wall " engine with excessive radial-part convergence ratio would reduce the detonation combustion efficiency, thereby reducing the detonation-wave parameters. Additionally, adding exit convergence or increasing the radial-part convergence makes the wave structure in the rotating detonation combustor more complex. The wave-head number in the combustor increases with an increase in the mass flow rate. At some special conditions, the asymmetric dual-wave mode and triple-wave mode are obtained in the combustor with large radial-part convergence ratio or adding exit convergence. For one propagation mode, its operating scope under the three configurations partially coincides, but the upper and lower limits of equivalence ratio and the operating scope of mass flow rate are greatly affected by the combustor configuration. Adding exit convergence can reduce the critical mass flow rate of modes switching, and broaden the stable operation range of the engine, but the "two-plane wall " engine with excessive radial-part convergence ratio could reduce the operating stability and its operating range. (C) 2022 Published by Elsevier Masson SAS.