The realization and stable operation of Continuous Rotating Detonation (CRD) in the annular combustor fueled by hydrocarbonair\nare still challenging. For further investigation of this issue, a series of ethylene-air CRD tests with the variation of combustor\nwidth is conducted, and the effects of combustor width are well analyzed based on high-frequency pressure and high-speed\nphotograph images. The results show that the combustor width plays a significant role in the realization and sustainability of the\nethylene-air CRD. In this paper, the critical combustor width for the CRD realization and stable single wave are 20mm and\n25 mm, respectively. In wide combustors, the backward-facing step at the combustor forepart makes the main flow slow down,\nand thus, the mixing quality is promoted. Besides, the pilot flame at the recirculation zone contributes to sustaining the CRD\nwave. As the width increases, the propagation mode changes from counter-rotating two-wave mode to single wave mode with\nhigher propagation velocity and stability. The highest propagation velocity reaches 1325.56 m/s in the 40mm wide combustor,\naccounting for 71.51% of the corresponding Chapman-Jouguet velocity. Despite large combustor volume, high combustor\npressure is obtained in detonation combustion mode indicating that a better propulsive performance could be achieved by CRD.
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