Abstract: In order to reveal the unstable propagation characteristic of rotating detonation wave in plane-radial structure, the two-dimensional numerical simulation was modeled in this structure for mixtures of 2H2+O2+3.76N2. Two typical propagation modes were obtained: the stable propagation mode and unstable propagation mode. The flow field structure under unstable propagation mode was analyzed in detail, as well as the variation of detonation parameters, flow parameters and the pressure amplifying ratio in exit. Results indicate that the decoupling and re-initiation of rotating detonation wave occur repeatedly under the unstable propagation mode. The diffraction of inner circle geometry weakens the detonation wave intensity, and the detonation wave decouples first near exit, then the decoupling region is expanding to the interior flow field gradually. The collision of reflected wave and leading shock wave urges the formation of hot spot in flow field, which initiates the detonation wave again. The detonation pressure, temperature and propagating velocity vary with the “decoupling and re-initiation” process of detonation wave. The unstable propagation of rotating detonation wave has only a small effect on the velocity components and Mach number in exit, but a large effect on the exit pressure amplifying ratio. The pressure amplifying ratio varies periodically with time, and the amplitude is high and unsteady. The period of pressure amplifying ration is consistent with the period of “decoupling and re-initiation” process, and the cycle frequency is about 21.6kHz after dynamic stability.

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