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

已知飞机发动机产生大量颗粒物质，包括在飞机的膨胀尾流中形成的燃烧气溶胶、硫酸盐液滴或冰粒。排放的颗粒可以通过增加背景气溶胶表面积密度和随后在颗粒上发生的非均相反应来影响大气的化学组成。凝结尾迹的形成和可能的云覆盖的增加也改变了地球的辐射收支，并可能导致气候变化。 为了帮助发动机制造商减少排放物的数量和正确评估航空对大气的影响，我们需要准确地表征气溶胶及其前体物在发动机后燃烧室区域以及飞机涡流尾流中的形成和演变。 目前已经使用详细的化学和微观物理方案进行了粒子形成和演变的模拟研究，但它们大多是在少数理想化的空气团轨迹上进行的，导致沿该轨迹的平均气溶胶特性沿着。在这些流动区域中，需要更复杂的基于计算流体动力学（CFD）的多维方法来考虑湍流扩散以及三维温度波动。 本建议旨在发展或改进有关飞机污染物（即颗粒物）在地面和飞行高度大气中的去向的新的预测能力。 该研究方案通过提供新的建模工具和更好地描述物理和化学过程来满足国际民航组织活动和认证程序的需要，这将有助于飞机发动机制造商和大气科学家确定飞机排放物对大气的贡献，特别是对飞机发动机释放的颗粒物的影响。

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.