Detailed kinetic modeling of soot aggregate formation in laminar premixed flames

Transition from coalescent to aggregate growth of soot particles in laminar premixed flames was investigated using detailed numerical simulations. A method-of-moments formulation for particle aggregation was developed on the basis of recent Monte Carlo simulations and coupled with a detailed chemical kinetics mechanism of soot formation. The combined model was applied to ensemble-averaged simulations of a number of burner-stabilized premixed laminar flames and compared to measurements. The effect of initial conditions on the transition from coalescent to aggregate growth was investigated by simulating a series of freely propagating laminar premixed flames. The instant of transition and the degree of aggregation were analyzed in relation to variations in fuel type, fuel/air equivalence ratio, and pressure. The analysis demonstrated a complex interaction of particle nucleation, surface growth, and coagulation, with nucleation playing a key role in the transition from coalescent to aggregate growth. The present conclusions are in accord with the prior theoretical study.