Spinning detonations propagating in a circular tube were numerically investigated with a one-step irreversiblereaction model governed by Arrhenius kinetics. The time evolution of the simulation results wasutilized to reveal the propagation mechanism of single-headed spinning detonation. The track angle of sootrecord on the tube wall was numerically reproduced with various levels of activation energy, and the simulatedunique angle was the same as that of the previous reports. The maximum pressure histories of theshock front on the tube wall showed stable and unstable pitch modes for the lower and higher activationenergies, respectively. The shock front shapes and the pressure profiles on the tube wall clarified the mechanismsof two modes. The maximum pressure history in the stable pitch remained nearly constant, and thesingle Mach leg existing on the shock front rotated at a constant speed. The high and low frequency pressureoscillations appeared in the unstable pitch due to the generation and decay of complex Mach interactionon the shock front shape. The high-frequency oscillation was self-induced because the intensity of thetransverse wave was changed during propagation in one cycle. The high-frequency behavior was notalways the same for each cycle, and therefore the low frequency oscillation was also induced in the pressurehistory.
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