High-speed schlieren visualization on the initiation process of non-premixed air and hydrogen continuous rotating detonation (CRD) is carried out in a well-designed rounded-rectangle hollow combustor in this study. The CRD initiation processes of pre-detonator ignition and spark plug ignition are comprehensively revealed by synchronous high-speed schlieren images and high-frequency dynamic pressure results. The results show that the CRD undergoes three processes after ignition, including initiation process, adjustment process and stable propagation process. The CRD initiation process of pre-detonator ignition involves the upstream-propagation phase of leading shock wave and reaction zone and the coupling phase of circumferentially-propagating shock wave and reaction zone, while that of spark plug ignition includes the upstream-propagation phase of reaction zone, and the coupling phase of circumferentially-propagating pressure wave and reaction zone. The formation of deflagration combustion flowfield and re-establishment of combustible mixture layer after ignition are important prerequisites for CRD initiation. The strong interaction between circumferentially-propagating shock wave and post-shock wave reaction conduces to the rapid initiation of CRD by pre-detonator ignition, while the pressure wave gradually interacts with reaction leading to the detonation initiation by spark plug ignition. The CRD initiation time and adjustment time of pre-detonator ignition are shorter than those of spark plug ignition. This study provides detailed insight into the physics of CRD initiation process of pre-detonator and spark plug ignition, which can deepen the understanding of the initiation mechanism and provide practical guidance for the optimal design of CRDE ignitor.

中文翻译：

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通过纹影可视化非预混连续旋转爆轰波的起爆过程

本研究在精心设计的圆角矩形空心燃烧室中对非预混空气和氢气连续旋转爆炸（CRD）的起爆过程进行了高速纹影可视化。通过同步高速纹影图像和高频动压结果全面揭示了雷管前点火和火花塞点火的CRD起爆过程。结果表明，CRD点火后经历了引发过程、调整过程和稳定传播过程3个过程。预雷管点火的CRD起爆过程包括前导冲击波和反应区的上游传播阶段以及周向传播冲击波和反应区的耦合阶段，而火花塞点火的CRD起爆过程包括反应的上游传播阶段区，以及周向传播压力波与反应区的耦合相。爆燃燃烧流场的形成和点火后可燃混合气层的重建是CRD引发的重要前提。周向传播的冲击波与冲击波后反应之间的强烈相互作用有助于通过雷管前点火快速起爆CRD，而压力波逐渐与反应相互作用导致火花塞点火起爆。预雷管点火的CRD起爆时间和调整时间比火花塞点火短。该研究对预雷管和火花塞点火的CRD起爆过程的物理原理进行了详细的了解，可以加深对起爆机理的理解，并为CRDE点火器的优化设计提供实用指导。