Experimental and numerical investigation on soot formation and evolution of particle size distribution in laminar counterflow ethylene flames

A detailed investigation of the process of soot formation in ethylene-fueled laminar counterflow diffusion flames is conducted using dedicated experiments and numerical simulations. Two different strategies based on the Discrete Sectional Method (DSM) and the Split-based Quadrature Method of Moments (S-EQMOM) are considered to model the evolution of soot particle size distributions, and their comparative assessment is carried out for soot formation prediction and particle growth. A consistent chemical reaction mechanism describing the oxidation of hydrocarbon fuels and the prediction of soot precursors with the growth of polycyclic aromatic hydrocarbons (PAHs) up to pyrene (C16H10) is examined. Experiments for various strain rates and fuel compositions are performed to assess the sensitivity of soot production to these two parameters. The results show that both modeling strategies captured well the qualitative trends of soot volume fraction under variations in strain rate and mixture composition, with slight over-prediction of the peak values. For both soot models, a higher sensitivity of soot formation is noticed by changes in mixture composition compared to those of strain rate variation. Additionally, the soot models demonstrated promising performance in capturing the experimentally observed evolution of the soot particle size distribution (PSD).