Simplified soot nucleation and surface growth steps for non-premixed flames

Abstract

Simplified reaction steps for the formation and growth of soot particles in laminar non-premixed flames are outlined. The resulting models are combined with detailed gas phase chemistry and incorporate simplified steps for nucleation, surface growth and particle agglomeration. The soot nucleation and surface growth reactions are linked to the gas phase chemistry by the simplifying assumptions that benzene and acetylene are indicative of the locations in the flame structure where nucleation and soot mass growth occurs. The reaction mechanisms are applied to a range of ethylene and propane counterflow diffusion flames and the sensitivity of soot predictions to different nucleation and surface growth formulations are investigated. The formation paths of benzene in flames of this type are also discussed due to the importance of aromatic species in soot nucleation. It is shown that good qualitative and quantitative agreement with measured data for soot volume fraction, particle growth and number density can be obtained using simplified reaction steps.