Experimental study on the auto-initiation of rotating detonation with high-temperature hydrogen-rich gas

An experimental study on the auto-initiation process of rotating detonation waves (RDWs) was conducted with high-temperature hydrogen-rich gas as the fuel and air as the oxidant. Spontaneous combustion of high-temperature hydrogen-rich gas and air occurred after they were injected into a rotating detonation chamber (RDC), which resulted in hot spots in the RDC and induced the formation of a rotating deflagration flame. Then, an RDW formed through the deflagration-to-detonation transition process in the RDC. The auto-initiation process of high-temperature hydrogen-rich gas and the formation mechanism of RDWs were studied in detail through experiments. The influences of the equivalence ratio on the RDW propagation characteristics of high-temperature hydrogen-rich gas were analyzed. The results showed that with the increase in the equivalence ratio from 0.61 to 1.93, five RDW propagation modes appeared in the RDC: Failure, two counter rotating detonation wave (TCRDW), Mixed, intermittent single rotating demodulation wave, and single rotating detonation wave (SRDW) modes. The Mixed mode was the transition mode from the TCRDW mode to the SRDW mode. The highest RDW velocity was 1485.9 m/s when the equivalence ratio was 1.32, in which the propagation mode was the stable SRDW mode.