Local quenching recovery mechanisms of interacting lean premixed and diffusion turbulent flames

Local quenching recovery mechanisms of lean premixed CH₄ air flame (LPF) and lean CH₄ diluted with N₂ diffusion flame (LDF) have been investigated experimentally for fundamental studies in heterogeneous mixture combustion. The local quenching phenomena are frequently observed with approaching the extinction limit. However, in many cases, the flame can recover from the local quenching phenomena. Two distinct local quenching recovery mechanisms, a passive local quenching recovery mode and an active local quenching recovery mode, have been observed. In the passive local quenching recovery mode, the local quenching occurs outside of the flame stability point and the flames can be automatically recovered from the local quenching phenomena in accordance with the flow field properties. In the active local quenching recovery mode, local quenching occurs including the flame stability point. In this case, the local flamelet propagation plays a key role to the recovery mechanism. The mechanism works well in the turbulence added in the premixed gas and also the mixture has to be in the self-propagating condition. In addition, the local quenching area might recover by the reacting flow transported by the eddy.