Combustion and thermal performances of methane-air premixed flame in a novel preheated micro combustor with a flame holder

Abstract

The laminar flame dynamics of the methane-air premixed mixture are investigated experimentally in a preheated micro combustor with a flame holder which can act as a micro heat source or a micro power source. The results reveal that the stability of the premixed flame is quite well before the flame extinction. The anomalous blow-off is found within the micro combustion chamber for the first time by the means of experiment and the correspondingly underlying mechanisms are also revealed. Besides, the blow-off dynamics are also discussed. The blow-off dynamics when the Reynolds number surpasses 240 remarkably differ from those when the Reynolds number is lower than 180. When the Reynolds number surpasses 240, the flame with local extinction and re-ignition periodically occurs first, then the residual flame shrinks upstream and ultimately extinguishes right behind the holder. When the Reynolds number is lower than 180, the oscillating flame appears first, then the flame becomes smaller and weaker over time before extinguishing completely near the flame tip in the end.