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

众所周知，飞机发动机会产生大量的颗粒物，包括燃烧的气雾剂、硫酸盐液滴或飞机尾迹膨胀时形成的冰粒。排放的颗粒物可以通过增加背景气溶胶表面积密度和随后在颗粒物上发生的非均相反应来影响大气的化学成分。尾迹的形成和可能的云层覆盖率的增加也改变了地球的辐射平衡，并可能对气候变化做出贡献。 为了帮助发动机制造商减少排放的物质，并正确地评估航空对大气的影响，我们需要准确地表征发动机燃烧室后区域以及飞机涡流尾迹中气溶胶及其前体的形成和演变。 目前已经使用详细的化学和微物理方案对粒子的形成和演化进行了模拟研究，但它们大多是在几个理想化的气团轨迹上进行的，导致沿该轨迹的平均气溶胶性质。在这些流动区域，需要一种更复杂的基于计算流体力学(CFD)的多维方法来考虑湍流弥散和三维温度波动。 本提案旨在发展或改进关于地面和飞行两级大气中飞机污染物(即颗粒物)去向的新的预测能力。 这项研究计划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求，这些过程将帮助飞机发动机制造商和大气科学家确定飞机排放对大气的贡献，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.