Optical correction methods for a simultaneous LII and TC measurement of a low-sooting LPG diffusion flame

Simultaneous measurements with the TwoColor emission and Laser-Induced-Incandescence techniques on a diffusion laminar LPG bunsen flame were performed. The acquired images were filtered, perspective corrected and processed via an on purpose made procedure in order to reduce the measuring error. For quantitative measurements of the soot volume fraction and temperature a tungsten lamp calibration method of LII and TC techniques was used. To correct the self-absorption and the laser attenuation through the flame, a correction method was developed by means of the laser extinction technique. Flame temperature distribution measured with the two-color method was validated with the corrected temperature measured with a fast thermocouple along the flame axis. Soot volume fraction were calculated with the two-color emission and LII and a good agreement was found. For quantitative measurements the influence of self-absorption and laser attenuation were found to be not negligible and an error of 12% was found as sum of the self-absorption and laser attenuation along the optical path.