Abstract
The colors of propane/air premixed flames were quantitatively characterized by the chromaticity coordinates (x, y) defined by the CIE 1931 standard colorimetric system. Detailed relations between flame colors and flame spectra were investigated in the range of air ratio from 0.7 to 1.2. The experimental results indicated that the chromaticity coordinates are useful to accurately express the change of flame color caused by the variation of air ratio. It was also found that the flame colors are mainly attributed to the relative spectral intensity of the CH bands, the C2 bands and the continuous spectrum and that the continuous spectrum plays an important role in the color determination, especially for the lean mixture. Moreover, it was suggested that flame color can be used to evaluate the air ratio and the relative spectral intensity. Thus the flame color could possibily be a valuable information source for combustion diagnostics, and is applicable to combustion control and monitoring systems.
