Abstract: To reveal the characteristics of unstable propagation of the rotating detonation wave in the plane-radial structure, a two-dimensional numerical simulation of the structure was conducted with 2H₂+O₂+3.76N₂ being the reaction mixture. The flow field structure under the unstable propagation mode was analyzed, as well as variation of detonation parameters, flow parameters and the pressure amplification ratio at the exit. Results indicate that decoupling and re-initiation of the rotating detonation wave occur repeatedly under the unstable propagation mode. The diffraction of the inner circle geometry weakens the intensity of the detonation wave. The detonation wave decouples first near the exit, and then the decoupling region expands to the interior flow field gradually. The collision of the reflected wave and the leading shock wave urges the formation of the hot spot in the flow field, initiating the detonation wave again. The detonation pressure, temperature and propagating velocity vary with the "decoupling and re-initiation" process of the detonation wave. The unstable propagation of the rotating detonation wave has only a small effect on the velocity components and Mach number in the exit, but a significant effect on the exit pressure amplification ratio. The pressure amplification ratio varies periodically with time, and the amplitude is high and unsteady. The cycle period of the pressure amplifying ratio is consistent with the period of "decoupling and re-initiation" process, and the cycle frequency is about 21.6 kHz after dynamic stability.

Key words: rotating detonation wave, numerical simulation, plane-radial structure, unstable propagation, detonation parameter