Flammability limits flame stretch

This section emphasizes on flame quenching by stretch, as well as highlights and separately discusses the four aspects of counterflow premixed flame extinction limits, including (1) effect of nonequidiffusion, (2) influence of different boundary conditions, (3) effect of pulsating instability, and (4) relahonship of the fundamental limit of flammability. 

Third, since the pulsating instability observed for the planar unstretched flame was expected to be promoted by positive stretch, pulsation may develop beyond a critical stretch rate smaller than the static extinction limit. As pulsating extinction occurred at a smaller stretch rate than the steady extinction limit, the flame extinguished in the pulsating, instead of the steadily propagating mode, and the flammable range was accordingly narrowed. 

In Chapter 6.3, C-J. Sung examines extinction of counterflow premixed flames. He emphasizes flame quenching by stretch and highlights four aspects of counterflow premixed flame extinction limits effect of nonequidiffusion, parf played by differences in boundary conditions, effect of pulsating insfabilify, and relation to the fundamental limit of flammability. 

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