The extinguishment experiments of the methane-air diffusion flame with the blast wave produced by a silver azide pellet of 10 mg have been performed. The extinguishment mechanism has been investigated by the schlieren visualization and the direct flame recording with a high-speed camera. As a result, it is found that the vortex pair motion in the flame appears due to the interaction between the shock wave and the diffusion combustion, that is, the Richtmyer-Meshkov instability. Moreover, the local extinction is caused by the vortex flow motion, and then the jetting flow spreads out from the combustion flame zone towards the surrounding air. The combustion gas of the explosive charge may also assist the jetting flow formation. Finally, the rest flames are blown off from the burner and the blast wave extinguishment is achieved. Thus, it can be said that the Richtmyer-Meshkov instability is the key factor to extinguishing a diffusion flame with a blast wave.
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