Flame imaging reconstruction method using high resolution spectral data of OH*, CH* and C2* radicals

This paper focuses on a technique to obtain images of the spatial distribution of ultraviolet OH*, visible CH* and C2* species present in hydrocarbon flames. This is achieved by combining sequentially acquired chemiluminescence spectra along slices defined by the entrance slit of an imaging spectrometer for narrow wavelength bands corresponding to the species of interest. As the analysis has been performed in an axisymmetric conical flame, the Abel inversion procedure has been applied to reduce the effect caused by the line of sight. The images resulting from the proposed reconstruction procedure are compared with the images collected with simple chemiluminescence visualization (detected with an ICCD camera) and respective narrow-band interference filters. Although the technique has been applied only in laminar steady flame condition, it could be interesting for application in more advanced, laser-sheet based diagnostics. The main advantages of the proposed technique are the high spectral resolution of the resulting radical images and the possibility of detecting other species (in the ultraviolet, visible or infrared regions) by combining chemiluminescence spectra at different wavelengths.