1 Temperature Measurements of Laminar Propane/Air Premixed Flame Using Detailed OH * Spectra Intensity Ratio

The spatially resolved chemiluminescence at the flame front and anchor point of a laminar premixed propane/air flame was measured in this study. The flame front structure, anchor point location, and local equivalence ratio were examined for different values of the equivalence ratio f ranging from 0.9 to 1.5 using the chemiluminescence spectra. Local point-measurements of the chemiluminescence were obtained using a developed Cassegrain optics system, which had a spatial resolution of d = 0.08 mm and L = 0.6 mm, sufficient to measure the detailed location of the anchor point and the flame front shape. The anchor point was not in the same location for different values of f. The lower anchor point was located 0.3 mm above the rim and at a radial distance of 6.8 mm when f = 1.0, 1.1, and 1.2, and the anchor point location trace was a V shape. The equivalence ratio of the anchor point was calculated from the relationship of the OH*/CH * intensity and the local equivalence ratio, and the measured value was constant for different values of f. The detailed OH * and CH* spectra demonstrated that the chemistry at the anchor point was dominated by the same processes for different equivalence ratios. The local equivalence ratio at the anchor point was between 0.7 and 0.8 for all experimental conditions. The temperature at the anchor point was estimated using the detailed OH * R and P branch intensity ratio used for plasma diagnostics. The results indicate that the temperature at the flame front was relatively constant, although the temperature at the anchor point showed remarkable changes that could be predicted from the heat loss