Wake Vortex Evolution During Approach and Landing With and Without Plate Lines

Abstract

Data from numerical simulations and two field measurement campaigns are used to investigate aircraft wake vortex evolution during final approach and landing with and without a plate line. A new hybrid simulation method is employed to capture wake vortex evolution from early roll-up to final decay in ground proximity. Vortex decay is driven by the turbulence of the aircraft wake itself, the interaction of the wake vortices with the ground, the so-called end effects triggered by the sudden loss of lift during touchdown, and it is artificially augmented by a plate line installed a few hundred meters from the runway threshold. The field experiments WakeMUC at Munich airport and WakeOP at special airport Oberpfaffenhofen corroborate and complement the findings of the simulations. The end effects together with an acceleration of the decay in close ground proximity significantly accelerate vortex decay nearby the runway. In view of the fact that the probability to encounter wake vortices is distinctly increased in ground effect, the described mechanisms ensure the required safety of air traffic operations. Experiments and simulations demonstrate that plate lines appreciably accelerate wake vortex decay and interfere favorably with end effects. This way safety can be further increased during the flight phase with most reported encounters.

Wind Impact on Single Vortices and Counterrotating Vortex Pairs in Ground Proximity

“…This implies that the reverse lateral transport is somewhat overestimated, as they still possess a large amount of circulation. With increasing headwind the rebound speed and height decrease due to the loss of coherence of the secondary vortices caused by the disturbances of the environmental turbulence and the resulting vortex stretching effects exerted by the primary vortex on its planetary vortex [49].…”

Multimodel Ensemble Methods for Prediction of Wake-Vortex Transport and Decay

“…Nevertheless, all landings regardless of the initial height are used to provide a statistically meaningful number of cases. The field campaigns that are used consist of WakeMUC [31], of which 374 high quality measurements were selected, and MEM95 [28] with 305 landings. For the evaluation of the BMA, the dataset was split into a training and a test sample with randomly selected landings.…”

“…Oberpfaffenhofen Field Experiment: Details on the field experiment are given in Holzäpfel et al [31]. Wake observations were made using a pulsed lidar.…”

“…Wake measurement data from lidar at Memphis (MEM95) [28], Dallas/Fort Worth [29], Denver [30], Munich (WakeMUC) [31], and at Oberpfaffenhofen (WakeOP) [31] are used for training and evaluation. The NASA datasets collected at the airports of Memphis, Denver, and Dallas contain wake history in all three phases of vortex descent, namely out-of-ground effect (OGE), near-ground effect (NGE), and in-ground effect (IGE), whereas the DLR, (German Aerospace Center) data gathered at German airports comprise vortices developing in NGE and IGE.…”

Multi-model ensemble wake vortex prediction

“…To find further evidence for the existence of the so-called end effects [7] mentioned in Chapter 2.8.2, the decay rate for various height intervals is evaluated. Under the assumption that these effects travel with a designated velocity and start from the touchdown point of the aircraft, faster decay rates would be expected for lower altitudes [159]. For this reason the cumulative distribution of vortex strength is evaluated for headwind speeds between 0-3 m/s, 3-6 m/s and for velocities larger than 6 m/s, and for the two intervals of vortex generation altitudes 0.4-1.2 b * 0 and 2.0-3.5 b * 0 .…”