Visual experimental investigation on initiation process of H_2/air rotating detonation wave in plane-radial structure

摘要

Using visual observation methods, assisted by synchronous measurement with high-frequency pressure sensors and ion probes, the initiation process of the plane-radial rotating detonation combustor under different operating modes are revealed. Results show that, the H-2/air rotating detonation wave (RDW) cannot be obtained directly by the low-energy spark plug owning to its low ignition energy. The RDW initiation processes under different modes are similar, which undergo the following processes: ignition, deflagration, chaotic turbulent flame acceleration (deflagration to detonation transition), unstable detonation, and stable rotating detonation. For multi-wave mode, the collision and mode switching mostly appear to occur in the initiation. The chaotic turbulent flame development process is further analyzed. The reactants' continuous injection and accumulation to a certain height is an important prerequisite for RDW initiation and stable propagation. The radial propagation of turbulent flames and collision promote the formation of hot spots, and the development of hot spots in reactants layer is an essential condition for the formation of circumferential flame. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.