Abstract: When detonation waves propagate in curved channels, they will be influenced by the curvature of the channel. Both the compression effect near the outer wall and the diffraction effect near the inner wall cause the detonation wave front to exhibit a certain degree of curvature, making the propagation more unstable due to decoupling between the shock wave and the chemical reaction. In order to clarify the propagation characteristics of detonation waves in curved channels, this study has been carried out using a mixture of ethylene, oxygen, and nitrogen to investigate the effects of the equivalence ratio and the dilution ratio on the propagation of stable detonation waves. The results imply that in curved channels, there are differences in the decouple mechanism between the fuel-lean and fuel-rich conditions. Under fuel-rich conditions, as the dilution ratio varies from 0.4 to 0.6, detonation waves transition from the regular reflection mode to the Mach reflection mode. Through comparing Dn/DCJ near the inner wall with 0.8DCJ, four propagation modes have been observed after the stable detonation waves enter the curved channel, i.e., a stable mode, a critical mode, a unstable mode and a deflagration mode. Under fuel-lean conditions, the dilu-tion ratio has a more significant impact on the detonation propagation mode. Finally, the critical conditions of the stable detonation mode have been clarified. The critical inner radius should be 18.6~24.2 times of the cell width.

Key words: curved channel, detonation wave, equivalence ratio, dilution ratio, propagation mode