Numerical study on the structures of counterflow flames of CO2-diluted methane

In this study, the possibility of ultra-diluted combustion of counterflow flames was investigated by numerical calculations using three counterflow flame models. As a result, the response curves of counterflow diffusion flame, counterflow double flames, and counterflow triple flames were produced separately, and the comparison shows that the triple flame is more difficult to extinguish than the double flame and diffusion flame. Then by chemical analysis, we found an important reaction which can be used as a criterion for determining the flame pattern of PPFs. Furthermore, as the dilution rate increases and extinction approaches, the double flame becomes a diffusion flame and the triple flame becomes a diffusion flame with a lean premixed flame. This characteristic inspired us to design a new partially premixed counterflow flame with similar extinction characteristics to the triple flame.