Spectroscopic and chemical characterization of soot inception processes in premixed laminar flames at atmospheric pressure

Abstract

Absorption, laser induced fluorescence and laser light scattering measurements have been performed in a slightly-sooting methane/oxygen flame at atmospheric pressure. Sampling and analysis has also been carried out with the aim of measuring and characterizing all of the condensable material formed during combustion. Scattering and extinction measurements in the uv and visible range allowed to determine simultaneously the volume fraction, the average size and number density of high molecular weight soot precursors and particles. The results suggest that there is an initial fast polymerization process with aromatic compounds as the building bricks. Particle inception is primarily controlled by the internal arrangement of these polymers leading to structures with more condensed aromatic rings and more compact 3-D shape, thus forming the first soot nuclei.