Enhanced Wake Vortex Decay in Ground Proximity Triggered by Plate Lines

Abstract

The highest risk to encounter wake vortices prevails in ground proximity, where the vortices cannot descend below the glide path but tend to rebound due to the interaction with the ground surface. Weak crosswinds may compensate the self-induced lateral propagation of the upwind vortex, such that it may hover over the runway directly in the flight path of the following aircraft. With the installation of plate lines at distances of a few hundred meters from the runway threshold, vortex decay in ground proximity can be substantially accelerated. A new hybrid simulation method is employed to capture wake vortex evolution in ground proximity from early roll-up to final decay. The numerical simulations reveal the nature of the disturbances triggered by the plate line and of so-called end effects driven by the sudden loss of lift during touchdown. Field measurement data gathered during the campaigns WakeMUC at Munich airport and WakeOP at special airport Oberpfaffenhofen corroborate and complement the findings of the simulations. Experiments and simulations demonstrate that plate lines appreciably accelerate wake vortex decay and interfere favorably with the end effects. This way safety can be further increased during the flight phase with most reported encounters.