Effect of ethylene-rich gas temperature on rotating detonation auto-initiation process

•The gas generator is combined with the rota detonation engine.•Detonation waves are generated spontaneously without pre-detonator.•The gas generator is combined with the rotating detonation engine.•Low gas temperature is not conducive to the deflagration-to-detonation transformation.•High gas temperature will produce secondary detonation wave.•Rich gas at higher temperatures contains more proportion of highly active ingredients. In this study, the propagation characteristics of a rotating detonation wave (RDW) between ethylene-rich gas and ambient air were investigated experimentally. The traditional pre-detonator initiation method was abandoned in the experiment, but the spontaneous combustion of high-temperature ethylene-rich gas and air was adopted. The RDW auto-initiated through the deflagration-to-detonation transformation (DDT) process. With an increase in the ethylene-rich gas temperature, the modes of RDW propagation appeared as delayed initiation, dual-wave collision, and fluctuating dual-wave collision modes. When the gas temperature was too high, a secondary detonation wave was produced near the head of the rotating detonation chamber (RDC), which affected the propagation efficiency and stability of the RDW. The increase in gas temperature expanded the equivalence ratio range of auto-initiation, which was due to the higher gas temperature, and more highly active components were precipitated.