Evolution of Carbonaceous aerosol and aerosol precursor emissions through a jet engine

This study conducted during the summers of 2000 and 2001 represents the first measurement and model intercomparison that tracks detailed gaseous and aerosol emissions through a gas turbine engine. Its primary objective was to determine the impacts of engine operational state on the evolution of carbonaceous aerosol and aerosol precursors. Emissions measurements were performed at the exit of a combustor and at the exit of a full engine for a gas turbine engine typical of the in-service, commercial aircraft fleet. Measurements were compared to model simulations of changes in gaseous chemistry. As predicted by the model simulations, results show no significant modifications to the aerosol distribution along the postcombustor flowpath. The oxidation of NO to HONO was measured. Trends with engine power setting and sulfur loading were at the level of estimated uncertainty limits. Simulations of the fluid and chemical processes through the turbine and exhaust nozzle correctly captured HONO trends and matched experimental data within measurement uncertainty. This suggests that the employed modeling approach is valid for HONO chemistry, and more generally, because HONO results from NO oxidation via the hydroxyl radical, indicates the importance of OH-driven oxidation through the engine. These results indicate that the chemical and physical processes occurring in the turbine are important in determining aircraft engine emissions.