Large Eddy Simulations of Turbofan Engine Exhaust Plume Dispersion on Take-Off Runway

Abstract

The pollution generated by the aircraft engines at the start of the take-off run is an important contributor to the local air quality in proximity to airports. The installation of an array of baffles in the runway strip behind the start of the runway, a configuration aiming to accelerate the lift-off of the exhaust plume, is numerically investigated. Validation tests are carried out in an effort to limit the computational cost. In this way, experimental data, including mean and RMS velocity profiles, as well as passive scalar concentrations, have been referenced. Additionally, a Dynamic Response Algebraic Model for Baffle Imitation (DRAMBI) has been devised. The numerical model is presented and tested. Experimental data obtained in the Atmospheric Boundary Layer Wind Tunnel (ABLWT) of Cranfield University, including drag force measurements and passive scalar concentrations, are used for the validation of the model. The predictions of DRAMBI are also compared to the results of conventional simulations including the baffle geometries. In this way, two-dimensional volume sections of mean and RMS contours of velocity and passive scalar, are presented and analysed. Finally, the axial momentum reduction required so that buoyancy becomes dominant and the plume naturally lifts-off, is investigated.