Effects of ignition condition on the initiation characteristics of rotating detonation wave in plane-radial structure

The ignition experiments of the plane-radial rotating detonation engine have been tested to identify the impact of ignition methods and ignition positions on the initiation characteristics of rotating detonation wave. The low-energy spark plug, high-energy spark plug and H-2/O-2 pre-detonation tube are used to ignite the engine. Results show that, for different ignition methods, the initiation process undergoes five stages: ignition, disordered deflagration, circumferential flame-wave propagation, unstable rotating detonation and stable rotating detonation. As the ignition energy increases, the circumferential flame wave is more easily obtained in combustor, and the initiation time of rotating detonation wave is shortened with better consistency. In this paper, the shortest initiation time is obtained by the H-2/O-2 pre-detonation tube. For the low-energy spark plug, as the mass flow rate increases, the average initiation time shows a downward trend with local fluctuation. When the rotating detonation engine is ignited close to the injection surface, the initiation time is shortened and fluctuates more slightly, and the optimal ignition position is obtained in the plane-radial combustor. Under specific operating conditions, changing the ignition position may affect the propagation mode of rotating detonation wave in the initial stage, and igniting close to the combustor center is more likely to obtain the multi-head rotating detonation wave. But changing the ignition method or ignition position has little effect on the propagation process and detonation-wave parameters in stable stage.