Engine emission alteration in the near field of an aircraft

The objective of this paper, which constitutes a part of the AERONOX project, is the investigation of the potential transformation of the active species emitted from aircraft into reservoir species. The analysis is based on modelling of transformations of the near-field region, 1 km behind a Boeing 767 and a Boeing 747 aircraft. The processes considered are, firstly the dynamics of the jet flow and the jet-wing tip vortices interaction and secondly the potential chemical transformations of species such as NO, NO2, HNO2, HNO3 and H2SO4. The wake dynamical processes are performed by using the 3D turbulent Navier-Stokes equations. Chemistry is calculated using a box model including the photochemical and heterogeneous reactions. In the jet flow, calculations have been performed for two engines CFM 56 and RB 211. Temperature fields and dilution profiles are compared. In the wake, the influence of the vortical motion on the inboard and outboard jet engines is shown. The chemical calculations show that there is a rapid disappearance of OH and HO2 at the very beginning of the plume and simultaneous growth of HNO2 and HNO3. All the main chemical transformations are made in the hot jet flow. In the limits of the calculations, there is no significant chemical transformations during the first kilometre behind the Boeing 767, except for OH, HO2 and CH2O2 whose concentrations appear highly dependent on the local exhaust NOx concentration. (C) 1997 Elsevier Science Ltd.