Experimental study of local quenching and recovery mechanisms for premixed diffusion combined combustion in an opposite turbulent flow

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In a heterogeneous combustion, an ultra-lean combustion is possible. However, the flame local quenching occurs at the turbulent condition. The local quenching will lead to decline the burning rate and to emit the unburnt hydrocarbon. In the present study, effects of turbulence and flame propagation on the local quenching and its recovery events have been studied experimentally by using opposed flows. As the results, the extinction criteria can be divided into two regimes depending on the thermal interpolation mechanisms. One is diffusion flame controlling condition and the other is premixed flame controlling condition. Three different local quenching events are observed: passive mode, active mode, and global extinction mode. Then, the quenching position, the turbulence and the propagation speed for the premixed flame side play important roles for the quenching and its recovering.