A simplified reaction mechanism for soot formation in nonpremixed flames

Abstract

The present article outlines a simplified reaction mechanism for the formation, growth, and combustion of soot particles in laminar nonpremixed flames. The model can be combined with detailed chemistry descriptions for the gas phase, as in the present case, or with reduced chemical reaction mechanisms. The reaction mechanism involves nucleation, surface growth, particle coagulation, and combustion steps. The model outlined has been created with the intention of being applicable to the prediction of turbulent flames via different approaches. The soot nucleation and surface growth reactions are linked to the gas phase by presuming that pyrolysis products, in the present case acetylene, and not the fuel itself, are of primary importance in the soot formation process. The deduced reaction mechanism is applied to counterflow ethylene and propane flames burning with a range of oxygen-enriched and -depleted air streams. The results obtained show excellent qualitative and quantitative agreement with measured data for soot volume fraction, particle growth, and number density.