Effect of cavity structure on flammability limit of n-butane partially premixed flame
The stability of partially premixed flame has a great influence on the safety,efficiency and emission of combustion device.This paper studies the flammability limit of n-butane partially premixed flame in cavity and non-cavity burner at a constant primary air coefficient by experiment and numerical simulation.The results show that,first,the flame stabilization range of the cavity burner is much larger than that of the non-cavity burner(a difference of about 2 orders of magnitude),especially with a more significant impact on the blow-out limit,which is mainly due to the unique double flame structure of the cavity burner(stuck vortex flame+external flame).Second,the trapped vortex flame in the cavity burner can continue to exist within a certain range after flashback or blowout of the external flame.Third,the key of the stabilization of the external flame is the heating of the wall by the trapped vortex flame.Such conclusions are intended to provide guidance for the design of partially premixed combustion units.
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