Aircraft emissions and environmental effects: Modelling of engine precursors & particulates in the post combustor gas flow and in the near field of the aircraft

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Aircraft engines are known to produce a large amount of particulate matter including combustion aerosols, sulphate droplets or ice particles formed in the expanding wake of the aircraft. The emitted particles can influence the chemical composition of the atmosphere by enhancing the background aerosol surface area density and the subsequent heterogeneous reactions that occur on the particles. Contrail formation and possible cloud coverage increase also modify the earth radiative budget and may contribute to the climate change. In order to help the engine manufacturers to reduce the amount of emitted material and to evaluate properly the aviation impacts on the atmosphere we need to characterize accurately the formation and evolution of aerosols and their precursors in the post combustor region of the engine as well as in the vortex wake of the aircraft. Current modelling study on particle formation and evolution have already been conducted, using detailed chemistry and microphysics schemes but they were mostly done on a few idealized air parcel trajectories, leading to average aerosol properties along this trajectory. In these flow regions, a more complex computational fluid dynamics (CFD)-based multidimensional approach is needed to take into account the turbulent dispersion as well as the three-dimensional temperature fluctuations. The present proposal aims to develop or improve new predictive capability concerning the fate of aircraft pollutants (i.e. particulate matters) in the atmosphere at both ground and flight levels. This research program addresses the needs of ICAO activities and certification procedures by providing new modelling tools and a better description of the physical and chemical processes that will assist aircraft engine manufacturers and atmospheric scientists in determining the contribution made by the aircraft emissions on the atmosphere and especially on the effects of the particulate matter released by aircraft engines.