Experimental study on propagation characteristics of stable detonation waves in curved channels

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. To clarify the propagation characteristics of detonation waves in curved channels, this study investigated the effects of the equivalence ratio and the dilution ratio on the propagation of stable detonation waves by using a mixture of ethylene, oxygen, and nitrogen. The results show that in curved channels, there are differences in the decoupling mechanism between the fuel-lean and fuel-rich conditions. Under fuel-rich conditions, as the dilution ratio varied from 0.4 to 0.6, detonation waves transitioned from the regular reflection mode to the Mach growth mode. By comparing the wave velocity on the inner wall with 0.8 times the C-J velocity, three propagation modes were observed after stable detonation waves entered the curved channel, i. e., a stable mode, a critical mode, and an unstable mode. Under fuel-lean conditions, the dilution ratio had a more significant impact on the detonation propagation mode. The critical condition of the stable detonation mode was clarified to be that the critical inner radius should be 18.6–24.2 times of the average cell sizes.