Numerical investigation on soot particle size distribution in turbulent non-premixed bluff body flames by using soot sectional method and detailed chemistry

Abstract

Purpose – This study aims to develop a new numerical framework for modelling soot formation and evolution via the soot particle size distribution (PSD) in turbulent flames. Design/methodology/approach – The numerical framework couples an extended soot sectional method with a finite-rate chemistry model based on detailed chemistry, which solves primary particle and soot aggregate number densities in every section with considering turbulence–chemistry interaction. Soot aggregates and gas species are solved simultaneously with considering differential diffusion and mass exchange between soot and chemical species. A dynamic load-balancing approach with a reference mapping model is also incorporated into the numerical framework to accelerate the parallel reacting flow simulations. Findings – This new numerical framework is comprehensively used to simulate soot formation and evolution in non-premixed turbulent sooting bluff body flames with different bluff body radii. With the bluff body radius increasing, the increased residence time of soot aggregates in the recirculation zone results in a significant shift of the PSD towards the larger soot aggregate side. The PSD shape always remains bimodal distribution at the centerline. Coagulation predominantly occurs at small soot aggregates, while the polycyclic aromatic hydrocarbon condensation and H-abstraction-C2H2-addition surface growth take significant effect at large soot aggregates. Originality/value – Overall good quantitative and qualitative agreements of numerical results with available experimental dataset demonstrate that the new numerical framework can accurately predict the flow properties and well capture the significant soot formation and evolution processes.