Effects of temperature stratification on the propagation of detonation wave

Non-uniform fuel distribution in a rotating detonation engine (RDE) combustor is generally considered to induce local deflagration combustion, leading to the temperature stratification of the combustible mixture ahead of the detonation wave. To thoroughly investigate the propagation mechanism, the propagation processes of the detonation wave under the condition of temperature stratification are extracted and numerically performed. Through the process of decoupling and re-initiation induced by the inert gas layer, a quantitative analysis was conducted on the effects of temperature gradient and stratification ratio on the propagation process. The results demonstrate that the propagation process with an inert gas layer can be categorized into stable propagation, detonation attenuation entering the layer, re-initiation penetrating the layer, overdriven, and re-stabilization phases. The detonation wave within the high-temperature layer propagates ahead under temperature-stratified conditions. The pressure disturbance generated by expansion gives rise to a localized high-pressure zone, facilitating re-initiation and significantly reducing the re-initiation distance. The re-initiation distance decreases substantially with the increase of temperature gradient and stratification ratio. Furthermore, it is found that excessively wide inert gas layer diminishes the enhancing effect of stratification conditions on re-initiation. This finding provides valuable insights for the propagation mechanisms of detonation waves in the actual RDE combustor over complex thermodynamic conditions.