Local quenching and recovery phenomena of turbulent premixed and non-premixed combined flames in an opposite flow

The local quenching and recovery phenomena of impinging lean premixed CH₄ air flame (LPF) and lean CH₄ diluted with N₂ non-premixed flame or diffusion flame (LDF) with different turbulence conditions have been investigated experimentally for fundamental studies of the heterogeneous lean combustion. The reacting flows are visualized by high speed time series of a particles image velocimetry (PIV). Near the global extinction limit, the local quenching phenomena observed frequently. However, the local quenching is not always trigger to develop the global extinction. Most of cases, the flame can recover from the local quenching phenomena. There are two distinct local quenching recovery mechanisms. One is passive recovery mode and other is active recovery mode. The local quenching possibility increases with approaching the extinction limit. It is worthwhile to see that the local quenching possibility for the turbulence added at the LPF side occurs more than 6 times compared with the turbulence added in the LDF side. It seems that the turbulence on the premixed flame works as a trigger for the local quenching and also helps to recover from the local quenching.