Progress in characterization of soot formation by optical methods. Bockhorn, H.; Geitlinger, H.; Jungfleisch, B.; Lehre, Th.; Schon, A.; Streibel, Th.; Suntz, R.: Physical Chemistry Chemical Physics (2002), 4(15), 3780-3793. ISSN: 1463-9076

Abstract

A two dimensional in situ optical technique is used to measure abs. soot vol. fractions, particle no. densities, and mean particle sizes in moderately sooting laminar and turbulent diffusion flames with high spatial and temporal resoln. These data are of special interest for the development and validation of models for the formation and oxidn. of soot. The technique (RAYLIX) is based on the simultaneous two dimensional detection of Rayleigh scattering and the laser induced incandescence (LII) in combination with the detection of the integral extinction from one single laser pulse. All signals are induced by a single pulse of a frequency doubled Nd-YAG laser. Besides mean particle sizes it si of special interest to derive information about the size distribution can then be obtained by simulating this decay using a LII model in combination with multidimensional non-linear regression. With this strategy the parameters describing the particle size distribution as well as the temp. of the surroundings gas phase are varied so that the calcd. decay of the LII signal is accordance with the measured one. In addn. to these quantities also probability-d. functions (PDF), correlation functions and length scales are derived from the soot vol. fraction in the turbulent flames. These quantities are of special interest for the modeling of turbulent reacting flows.