Investigation of counter-rotating shock wave phenomenon and instability mechanisms of rotating detonation engine with hollow combustor and Laval nozzle

The counter-rotating shock wave phenomenon and instability mechanisms in the hollow rotating detonation combustor with a Laval nozzle are investigated. The in-house solver BYRFoam based on the OpenFOAM platform and the detailed chemical reaction kinetic mechanism are used. The coupling of the detonation wave and the shock wave is revealed, with the continuous presence of the counter-rotating shock wave in the combustor that propagates in the opposite direction to the detonation wave and oscillates in intensity. The intensities of both the detonation wave and the counter-rotating shock wave are found to be constantly oscillating, and this instability is referred to as the collision-oscillation instability. It is caused by the complex interaction between the detonation wave, the fresh gas and the counter-rotating shock wave. The velocity difference between the detonation wave and the counter-rotating shock wave is found to lead to the migration of the collision point, which in turn leads to the peak periodic undulation phenomenon of the pressure curve, that is, the wave packet. This instability is called the counter-rotating instability, which co-exists with the collision-oscillation instability for a long time. The results of this study are compared with the experimental data, and the reasons for the oscillation of the experimental pressure signal are explained. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.