Strategies for Circulation Evaluation of Aircraft Wake Vortices Measured by Lidar

Holzäpfel, Frank; Gerz, Thomas; Köpp, F.; Stumpf, Eike; Harris, Michael; Young, Robert I. M.; Dolfi-Bouteyre, Agnès

doi:10.1175/1520-0426(2003)020<1183:sfceoa>2.0.co;2

Cited by 68 publications

(53 citation statements)

References 10 publications

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“…Circulation is averaged over circles with radii from 5 to 15 m. Benefits and drawbacks of radii-averaged circulation definitions are discussed in [48].…”

Section: Vortex Initializationmentioning

confidence: 99%

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

Holzäpfel

Tchipev

Stephan

2016

Flow Turbulence Combust

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Wall-resolved large eddy simulations are employed to investigate the behaviour of wake vortices and single vortices in ground proximity at a variety of wind conditions. The six considered strengths of wind, ranging between 0.5 and 4 times the initial wake vortex descent speed, w 0 , include practically and theoretically significant wind speeds. A crosswind of 0.5 w 0 may lead to windward stall posing a potential hazard to subsequently landing aircraft, whereas theoretical considerations predict that at 4 w 0 the rebound of the luff vortex is completely suppressed. The same range of wind speeds is also used to investigate the effects of headwind and diagonal wind in order to discriminate between effects of environmental turbulence increasing with wind speed and the direction of the wind shear. The study has been complemented by a number of single vortex computations in order to differentiate between effects related to the mutual interaction of the vortex pair and the individual vortices with the turbulent boundary layer flow. It is shown that vortex ascent, descent, rebound and decay characteristics are controlled by (i) the interaction of the vortices with secondary vorticity detaching from the ground, (ii) the redistribution of vorticity of the boundary layer which is altering the path of the primary vortices by mutual velocity induction, and (iii) the interaction of the vortices with the environmental turbulence.

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“…Circulation is averaged over circles with radii from 5 to 15 m. Benefits and drawbacks of radii-averaged circulation definitions are discussed in [48].…”

Section: Vortex Initializationmentioning

confidence: 99%

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

Holzäpfel

Tchipev

Stephan

2016

Flow Turbulence Combust

Self Cite

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“…Further, * 5−15 allows comparing circulation data from simulation, field measurement, and laboratory experiments. 47 In Fig. 4(b), the normalized average circulation obtained from the vorticity component in flight direction * 5−15 is denoted by lines, and lines with symbols denote the normalized average circulation determined along the vortex centerline˜ * 5−15 .˜ * 5−15 is estimated based on a predictor-corrector algorithm which realizes robust identification of the vortex centerline.…”

Section: A Temporal Evolutions Of Vortex Parameters and Topologymentioning

confidence: 99%

Vortex bursting and tracer transport of a counter-rotating vortex pair

et al. 2012

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Large-eddy simulations of a coherent counter-rotating vortex pair in different environments are performed. The environmental background is characterized by varying turbulence intensities and stable temperature stratifications. Turbulent exchange processes between the vortices, the vortex oval, and the environment, as well as the material redistribution processes along the vortex tubes are investigated employing passive tracers that are superimposed to the initial vortex flow field. It is revealed that the vortex bursting phenomenon, known from photos of aircraft contrails or smoke visualization, is caused by collisions of secondary vortical structures traveling along the vortex tube which expel material from the vortex but do not result in a sudden decay of circulation or an abrupt change of vortex core structure. In neutrally stratified and weakly turbulent conditions, vortex reconnection triggers traveling helical vorticity structures which is followed by their collision. A long-lived vortex ring links once again establishing stable double rings. Key phenomena observed in the simulations are supported by photographs of contrails. The vertical and lateral extents of the detrained passive tracer strongly depend on environmental conditions where the sensitivity of detrainment rates on initial tracer distributions appears to be low.

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“…For theoretical reasons and properties of the LIDAR technique it is beneficial to compute the circulation as an average over distances from the vortex core centre (here for radii between 5 and 15 m) [43]. • The complex wake vortex behaviour found in observations and simulations illustrates the challenges connected with the development of a thorough real-time model.…”

Section: The Probabilistic Two-phase Model P2pmentioning

confidence: 99%