Aerosol Dynamics in the Near Field of Engine Exhaust Plumes

Abstract

A simulation methodology previously employed to study the effect of large- and small-scale turbulent mixing on gaseous chemistry in engine exhaust plumes has been extended in this study to investigate aerosol dynamics. An efficient aerosol model that simultaneously treats condensation, nucleation, and coagulation has been developed using the method of moments to investigate the impact of microscale mixing on sulfuric acid aerosol distribution in the engine exhaust plume. The initial SO3 conversion rate at the engine exhaust plane was systematically varied to evaluate its effects on aerosol density and surface density distributions in the jet plume. The model shows reasonable predictions of aerosol number density, aerosol surface density, and critical gas species in the near-field plume. There is a significant discrepancy in the predicted aerosol number density in the jet plume when microscale mixing is neglected. Results show that peak number density is underpredicted by about 40% without micromixing, which suggests that the mixing process in the engine plume could have a nonnegligible impact on the overall aerosol distribution. The computational efficiency of the aerosol model developed here also provides a framework for incorporating aerosol dynamics into large-eddy simulation models for three-dimensional simulations of near-field plume?vortex interactions.