Effects of ozone on laminar premixed flames in nitrogen coflow

In this study, the effects of ozone (O3) on blowoff of methane-air and propane-air flames were investigated experimentally by using a coflow burner. It showed that a flame height decreased and the location of a flame base shifted toward the nozzle by adding ozone. Blowoff velocities (ub.o.) significantly increased as well as extended both lean and rich flammability limits by adding ozone. The percent enhancement in the blowoff velocity was pronounced at the off-stoichiometric mixtures where the blowoff velocities increased up to 16% and 20% for the methane-air and the propane-air flames, respectively. The dependency of the blowoff velocity on the concentration of ozone was found to be linear. For φ > 1.2, the methane-air mixture showed better percent enhancement in blowoff velocity than the propane-air mixture, while for the rest of mixture conditions the effect of ozone to promote the blowoff stability was stronger for the propane-air mixture.