Impact of Wind and Obstacles on Wake Vortex Evolution in Ground Proximity

Holzäpfel, Frank; Stephan, Anton; Tchipev, Nicola; Heel, Tobias; Körner, Stephan

doi:10.2514/6.2014-2470

Cited by 10 publications

(15 citation statements)

References 9 publications

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“…Analytical considerations of Doligalski [107] imply that vortex rebound is suppressed if the crosswind speed exceeds 4w 0 , which has also been observed in DNS [102] and LES [22]. The maximum descent height of the lee vortex, however, increases continuously with increasing crosswind speed [22].…”

Section: In-and Near-ground Effectsupporting

confidence: 54%

“…This leads to a more pronounced rebound of the lee vortex [102] and furthermore shortens its lifespan due to an increased level of turbulence [101,106]. Analytical considerations of Doligalski [107] imply that vortex rebound is suppressed if the crosswind speed exceeds 4w 0 , which has also been observed in DNS [102] and LES [22]. The maximum descent height of the lee vortex, however, increases continuously with increasing crosswind speed [22].…”

Section: In-and Near-ground Effectmentioning

confidence: 74%

“…In 2011 the WakeMUC campaign [22] has been accomplished at Munich airport. Between 11th of March and 12th of May 2011 LiDAR measurements of 779 landings of heavy and medium type aircraft have been collected on runway 26L [22]. The LiDAR was positioned at a distance of 850 m northerly of the runway center line.…”

Section: Wakemucmentioning

confidence: 99%

“…To ensure that the results are statistically significant, a sufficiently large amount of wake vortex field measurements is required. For this purpose the WakeMUC campaign [22] is evaluated and used for the development of the MME. Additionally, data from field experiments at Frankfurt (WakeFRA) [23], special airport Oberpfaffenhofen (WakeOP) [22], Dallas (DFW97) and Memphis (MEM95) [24] airport are employed.…”

mentioning

confidence: 99%

“…For this purpose the WakeMUC campaign [22] is evaluated and used for the development of the MME. Additionally, data from field experiments at Frankfurt (WakeFRA) [23], special airport Oberpfaffenhofen (WakeOP) [22], Dallas (DFW97) and Memphis (MEM95) [24] airport are employed. Eventually, it shall be assessed whether the MME approach bears the chance of covering rare but dangerous wake vortex cases under the assumption that the ensemble members are experts on different fields.…”

mentioning

confidence: 99%

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Multi-model ensemble wake vortex prediction

Körner

Holzäpfel

2016

Aircraft Eng & Aerospace Tech

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Tag der mündlichen Prüfung: 25.07.2017 Diese Dissertation ist auf den Internetseiten der Universitätsbibliothek online verfügbar. Für meinen Großvater. v Eidesstattliche Erklärung Ich versichere hiermit an Eides Statt, dass ich die vorliegende Dissertation mit dem Titel "Multi-Model Ensemble Wake Vortex Prediction" selbstständig und ohne unzulässige fremde Hilfe erbracht habe. Ich habe keine anderen als die angegebenen Quellen und Hilfsmittel benutzt. Für den Fall, dass die Arbeit zusätzlich auf einem Datenträger eingereicht wird, erkläre ich, dass die schriftliche und die elektronische Form vollständigübereinstimmen. Die Arbeit hat in gleicher oderähnlicher Form noch keiner Prüfungsbehörde vorgelegen. Zudem versichere ich Eides statt, dass ich kein erfolgloses Promotionsverfahren bzw. Promotionsstudium zum Dr.-Ing/ Dr.rer.nat. durchgeführt habe. AbstractAs a response to lift, a complex flow pattern is shed from the wings of an aircraft that evolves into a pair of counter-rotating vortices. Their behavior is strongly influenced by the atmosphere and further underlies a complex interaction with the ground. Due to the rolling momentum that the vortices may induce and the forces that they can exert they pose a potential hazard to following air traffic, especially along the glide path and in ground proximity. To avoid dangerous incidents, separation regulations based on aircraft mass exist that is currently under revision in the context of RECAT. However, air traffic is expected to further increase in the future, making wake vortex encounters more likely. For this reason fast-time wake vortex models have been developed in the past that predict the vortex position and strength dependent on the aircraft parameters and the ambient conditions in order to avoid dangerous situations. Furthermore, they may reduce flight delays at congested airports as they allow adapting overly conservative separations tactically under certain conditions. However, forecasts include uncertainties that originate from inaccurate and highly variable initial and ambient conditions as well as from inadequate understanding and simplification of the underlying physics. As a consequence, deterministic forecasts are to be complemented by probabilistic envelopes.In the field of meteorology such envelopes are frequently computed by combining the forecasts of multiple independent models to quantify the model uncertainty. This approach, also known as Multi-Model Ensemble (MME), has not only shown to increase the reliability of the probabilistic forecast but also to enhance its deterministic skill. For this reason the capability of the MME approach to improve both deterministic and probabilistic wake vortex forecasts is assessed and existing approaches are further developed in this thesis. Three of the ensemble members have been provided in the frame of a NASA-DLR cooperation. The employed models comprise APA 3.2, APA 3.4 and TDP 2.1 (NASA) and are combined with the DLR model D2P. Several MME approaches are examined, comprising the Direct Ensemble Average...

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Section: In-and Near-ground Effectsupporting

confidence: 54%

Section: In-and Near-ground Effectmentioning

confidence: 74%

Section: Wakemucmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Multi-model ensemble wake vortex prediction

Körner

Holzäpfel

2016

Aircraft Eng & Aerospace Tech

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Investigation of Lamb–Oseen Vortex Evolution and Decay in Ground Proximity With Obstacle

Zhang

2018

Journal of Fluids Engineering

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The physical mechanism for the evolution and decay of Lamb–Oseen vortex pair in ground proximity with an obstacle has been investigated in detail by adopting the large eddy simulation (LES). In the present research, we mainly focus on the vortex evolution and decay mechanism in ground proximity with obstacle, so we chose one fixed height of the obstacle case (h0 = 0.5b0) to investigate, and the obstacle is placed transversally to the axis of the primary wake to be analyzed. The trajectories of the primary wake-vortex cores and the circulation profiles, as well as the distribution of the tangential velocity on different axial positions, have been specifically captured and analyzed. The “strake,” “claw,” and “ivory” vortices have been newly found and defined at the initial evolution stage, and they subsequently begin to harshly wind and rotate with the primary vortex. A flow structure with double helix conical shapes of the primary vortex has been found in the obstacle case. The pressure waves along the vortex axis have also been analyzed in detail. The wake-vortex on each side would be pulled in opposite axial directions and eventually pinched off at the upper surface of obstacle. Moreover, it has also been newly found that the trajectories of the wake-vortex in longitudinal directions at different axial distances away from the obstacle will experience two kinds of motion: only descending and rebounding after descending. Results obtained in this study provide a better understanding of mechanisms for the interaction of wake-vortex and the obstacle.

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Large Eddy Simulation Research on the Evolution Mechanism of Aircraft Wake Influenced by Cubic Obstacle

et al. 2022

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Aircraft wake is a kind of intense air movement, and the study of its generation, development, and dissipation law is of great significance to the flight safety. There are abundant researches on the evolution of aircraft wakes affected by weather and ground effects; however, there are few studies on the influence of a single obstacle on the evolution of aircraft wake. In this article, in order to explore the influence of a single obstacle on the evolution of aircraft wake, firstly, we develop a computational fluid dynamics-based method of simulation of aircraft wake affected by cubic obstacle of different heights in order to obtain the wake intensity changes and position changes before and after being affected by the obstacle. Then, the result data are visualized and analyzed, and we obtain the results of velocity and Q criterion contours, circulation, and data related to wake vortex structure. CFD simulations are conducted, including the cases of the vertical distance between wake vortex and obstacle which is 20 m, 60 m, 100 m, and no obstacle. The quantitative results indicate that a single obstacle also has a great influence on the evolution of the wake vortex. Obstacle will shorten the time for the wake vortex to enter the fast decay stage, and the smaller the distance the wake vortex is above the obstacle, the faster it enters the fast decay stage. In the same time, the circulation will reduce 20% more under the same calculation time when the wake is 20 m above the obstacle than when the wake is 100 m above the obstacle, and the circulation will reduce 45% more than when there is no obstacle. Single obstacle also leads to the generation of multiple secondary vortices and rotates around the wake vortex, resulting in the increase of wake vortex core radius, wake vortex core spacing, and wake vortex height.

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Impact of Wind and Obstacles on Wake Vortex Evolution in Ground Proximity

Cited by 10 publications

References 9 publications

Multi-model ensemble wake vortex prediction

Multi-model ensemble wake vortex prediction

Investigation of Lamb–Oseen Vortex Evolution and Decay in Ground Proximity With Obstacle

Large Eddy Simulation Research on the Evolution Mechanism of Aircraft Wake Influenced by Cubic Obstacle

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