Effects of turbulence and flame propagation on the local quenching

Effects of turbulence and flame propagation on the local quenching and its recovery events have been studied experimentally by using two-dimensional cross correlation PIV movies. Opposed flows, one jet is formed by laminar flow and the other by turbulent flow are used to investigate the effect of turbulence on the local quenching. As the selected gases jets, one is lean premixed methane air and the other is methane diluted by nitrogen. The formed flames are combined by a lean premixed flame and a diffusion flame. 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. If the local quenching occurs without the stagnating point, the flames may possible easily recovering from the local quenching event, because the local quenching region are swiped by diverging flow motion. This mode is named as passive mode. On the other hand, if the local quenching occurs within the stagnating point, to recover the quenching event, the flames must propagate or re-ignite. Then, the edge part of premixed flame propagation mechanism plays a key factor.