Multi-dimensional Modeling of Soot Formation in DISI Engines Based on Detailed PAH Kinetics and Particle Dynamic Framework

In this study, in-cylinder soot formation in direct-injection spark-ignition engines was modelled based on the combined framework of detailed polycyclic aromatics hydrocarbon (PAH) chemical kinetics and particle dynamics. The turbulent flame propagation in partially premixed condition was described by G-Equation, while the chemical compositions behind of the flame front were determined by flamelet library which incorporates the PAHs kinetics. The post flame particle dynamics includes further growth of PAHs and particle inception, surface growth, coagulation and oxidation, and it is modelled by method of moments. In order to improve the model prediction through whole mixing and combustion process, the droplet distribution of spray injection was tuned by measuring sauter mean diameter from rig test, and the laminar flame speed was calculated using mixing rule. The numerical simulation was validated with the single-cylinder research engine experiments under cold start, catalyst heating conditions. The developed model were able to represent the basic physics of soot formation and bridge the gap between operating parameters and engine-out soot emissions with enhanced interpretation capability.