Plume and wake dynamics, mixing, and chemistry behind a high speed civil transport aircraft

Abstract

The environmental perturbations caused by the exhaust of a high speed civil transport (HSCT) depend on the deposition altitude and the amount and composition of the emissions. The chemical evolution and the mixing and vortical motion of the exhaust need to be analyzed to track the exhaust and its speciation as the emissions are mixed to atmospheric scales. Elements of an analytic model of the wake dynamical processes are being developed to account for the roll-up of the trailing vorticity, its breakup due to the Crow instability, and the subsequent evolution and motion of the reconnected vorticity. The concentrated vorticity is observed to wrap up the buoyant exhaust and suppress its continued mixing and dilution. The chemical kinetics of the important pollutant species will be followed throughout the plume and wake. Initial plume mixing and chemistry are calculated using an existing plume model, standard plume flowfield (SPF), with additional H/C/O, OH/SO2, and NOj, chemistry and equilibrium H2O condensation included. The species tracked include those that could be heterogeneously reactive on the surfaces of the condensed solid water (ice) particles when condensation occurs, and those capable of reacting with exhaust soot particle surfaces to form active contrail and/or cloud condensation nuclei (ccn).