Detailed local spectra measurement in high-pressure premixed laminar flame

Abstract

Detailed flame spectrum in a premixed laminar flame was investigated. The chemiluminescent spectrums at elevated pressure were measured by spatially resolved Cassegrain optics systems, which has a high spatial resolution of d = 0.1 mm and L = 0.8 mm. The chemiluminescence at different pressures was examined to identify the main OH*, CH* and C2* spectra. Background spectra related to CO-O* were observed at pressures greater than 0.5 MPa. Detailed OH* and CH* spectra were measured at different pressures, and the results indicate that each vibrational and rotational peak are in the same location, regardless of the pressure. The chemiluminescence intensity ratio of OH*/CH* at different pressures was examined. Less dependence on pressure was observed, although the individual chemiluminescence intensities changed with increasing pressure. The CO-O* broadband spectrum was significant at 0.5 MPa; its intensity remained at the same level at pressures greater than 0.5 MPa. This background spectrum was not observed at 0.1 MPa. In order to examine these chemiluminescence intensity profiles with the reaction zone and there dependence on pressure, peak location of OH*, CH* and C2* were measured. The OH* peak was located inside the CH* and C2* curves for all measured pressures.