Radical luminescence from premixed flame. Characteristics of radical luminescence spectrum from flames of gasoline, methanol and methane, and equivalence ratio dependence

The possibility of combustion diagnostics through the measurement of radical luminescence is discussed in this paper. Radical species in premixed flames of gasoline, methanol and methane are explored using spectroscopic measurements. It was found that major species having strong radical luminescence are OH, CH and C₂ for gasoline and methane, and OH and CH for methanol. The effects of the equivalence ratio and premixed gas temperature on spectral intensities are discussed. We found that the correlation between the equivalence ratio and spectrum intensity ratio of two radical species is linear. There is a possibility of predicting the equivalence ratio from the measurement of the radical emission intensity of a flame.