ESR Studies of Bunsen-type Methane-Air Flames. I. Effects of the Entrainment and Diffusion of Secondary Air on the Chemical Reactions in the Flame

Abstract

Abstract H atoms in a Bunsen-type methane-air flame have been studied by observing their ESR signals at different flow rates of O2 and N2 in a synthetic secondary air. The optical emissions from excited CH, C2, and OH radicals in the same flame have been also studied. It has been found that an increased O2 flow rate produces changes in the intensity of the ESR and emission signals, and that it also increases the burning velocity in the inner-cone flame. An increased N2 flow rate, on the other hand, has almost no effect on the flame. The inner-cone of a Bunsen-type flame is, therefore, not a completely premixed flame; it is affected chemically by the secondary air.