Aerosol dynamics in the near field of engine exhaust plumes

A simulation methodology previously employed to study the effect of large- and small-scale turbulent mixing on gaseous chemistry in engine exhaust plu mes has been extended in this study to investigate aerosol dynamics. An eff icient aerosol model that simultaneously treats condensation, nucleation, a nd coagulation has been developed using the method of moments to investigat e the impact of microscale mixing on sulfuric acid aerosol distribution in the engine exhaust plume. The initial SO3 conversion rate at the engine exh aust plane was systematically varied to evaluate its effects on aerosol den sity and surface density distributions in the jet plume. The model shows re asonable predictions of aerosol number density, aerosol surface density, an d critical gas species in the near-field plume. There is a significant disc repancy in the predicted aerosol number density in the jet plume when micro scale mixing is neglected. Results show that peak number density is underpr edicted by about 40% without micromixing, which suggests that the mixing pr ocess in the engine plume could have a nonnegligible impact on the overall aerosol distribution. The computational efficiency of the aerosol model dev eloped here also provides a framework for incorporating aerosol dynamics in to large- eddy simulation models for three-dimensional simulations of near- field plume-vortex interactions.