Laser-induced incandescence and Raman measurements in sooting methane and ethylene flames

Abstract

Laser-induced incandescence (LII) of soot particles is modeled using two non-linear coupled differential equations deduced from the energy- and mass-balance of the process. Experimental data of laminar sooting diffusion flames are taken and the model function is fitted to the individual data curves of every pixel in the two-dimensional flame image. The results of the least squares fit are maps of the soot particle radii and number densities in the flame. Methane and ethylene flames are examined and the results are compared with former measurements. The quality of this fitting algorithm is compared to the reproduction of the data curves by a conventional data evaluation method. The fitting routine for the methane flame is improved by providing local temperature data obtained by Raman measurements. Results for this flame are compared with the local gas concentrations.