On the one hand, it is known from visual observations, Lidar measurements, and numerical simulations that aircraft wake vortices may live significantly longer than anticipated by todays standard regulations of air traffic control. On the other hand, the initially counter-rotating, parallel vortex pair deforms quickly, which reduces the impact time of adverse forces and moments on encountering aircraft. Therefore, large-eddy simulations of wake vortex evolution in different meteorological conditions are conducted in order to analyse the physics of vortex deformation. A new post-processing algorithm has been developed that at first determines the three-dimensional path of the vortex core line and then computes piecewise curvature radii as a measure of vortex deformation. It is found that larger turbulence levels and neutral to weakly stable temperature stratification particularly support vortex ring formation. The vortex ring regime is characterized by a reduced descent rate and by a surprising variability of its core radius. It is shown that the varying core size directly affects the evolution of radii-averaged circulation. Comparisons with field experiments indicate good agreement with the considerable life time of the vortex rings and topology.
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References
1.
Delisi, D. P. Laboratory measurements of the effect of ambient turbulence on trailing vortex evolution. In 44th AIAA Aerospace Sciences Meeting and Exhibits, AIAA, San Reno, USA 2006.
2.
HolzäpfelF.Probabilistic two-phase aircraft wake-vortex model: further development and assessment. J. Aircraft, 2006, 43(N3), 700–708.
GreeneG. C.An approximate model of vortex decay in the atmosphere. J. Aircraft, 1986, 23, 566–573.
9.
SarpkayaT.New model for vortex decay in the atmosphere. J. Aircraft, 2000, 37(N1), 53–61.
10.
WinckelmansG.DuquesneT.TreveV.DesenfansO.BricteuxL.Summary description of the models used in the Vortex Forecast System (VFS), Univ. Catholique de Louvain, Louvain la Neuve, Belgium, 2005).
11.
HolzäpfelF.Probabilistic two-phase wake vortex decay and transport model. J. Aircraft, 2003, 40(N2), 323–331.
12.
Proctor, F. and Hamilton, D. W. evaluation of fast-time wake vortex predictions models. In Proceedings of the 47th AIAA Aerospace Sciences Meeting, AIAA, Orlando, USA, 2009.
13.
Melander, M. V. and Hussain, F. Cut-and-connect of two antiparallel vortex tubes. In Proceedings of the Summer Program, Center for Turbulence Research, 1988, N89 24559, pp. 257–286.
14.
KidaS.TakaokaM.Vortex reconnection. Ann. Reve Fluid Mech., 1994, 26, 169–189.
15.
KaltenbachH.-J.GerzT.SchumannU.Large-eddy simulation of homogeneous turbulence and diffusion in stably stratified shear flow. J. Fluid Mech., 1994, 280, 1–40.
16.
GerzT.HolzäpfelF.Wing-tip vortices, turbulence, and the distribution of emissions. AIAA J., 1999, 37(N10), 1270–1276.
17.
HolzäpfelF.Adjustment of subgrid-scale parametrizations to strong streamline curvature. AIAA J., 2004, 42, 1369–1377.
18.
HolzäpfelF.GerzT.BaumannR.The turbulent decay of trailing vortex pairs in stably stratified environments. Aerosp. Sci. Technol., 2001, 5(N2), 95–108.
19.
HintonD. A.TatnallC. R.A candidate wake vortex strength definition for application to the NASA aircraft vortex spacing system (AVOSS). NASA-TM-110343,, 1997.
20.
CrowS. C.BateE. R.Lifespan of trailing vortices in a turbulent atmosphere. J. Aircraft, 1976, 13(N7), 476–482.
21.
JeongJ.HussainF.On the identification of a vortex. J. Fluid Mech., 1995, 285, 69–94.
22.
ChongM. S.PerryA. E.CantwellB. J.A general classification of three-dimensional flow fields. Phys. Fluids, 1990, 5, 050765–050765.
23.
KidaS.MiuraH.Identification and analysis of vortical structures. Eur. J. Mech. - B/Fluids, 1998, 17, 471–488.
24.
Banks, D. C. and Singer, B. A. Vortex tubes in turbulent flows: identification, representation, reconstruction. In Proceedings IEEE Conference Visualization '94, 17–21 October 1994, CP14, pp. 132–139.
25.
Hennemann, I. and Holzäpfel, F. Aircraft wake vortex deformation in a turbulent atmosphere. In Proceedings of the 5th International Symposium on Turbulence and shear flow phenomena, TU Munich, Garching, Germany, 2007, pp. 597–602.
26.
Hennemann, I. and Holzäpfel, F. Aircraft wake vortex curvature and resulting risk potential for following aircraft. In Proceedings of the CEAS European Air and Space Conference, Manchester, UK, 2009.
27.
Proctor, F. and Switzer, G. Numerical simulation of aircraft trailing vortices. In Proceedings of the 9th Conference on Aviation, range and aerospace meteorology, American Meteorology Society, Orlando, USA, 2000, pp. 511–516.
28.
LaporteF.LewekeT.Elliptic instability of counter-rotating vortices: experiment and direct numerical simulation. AIAA J., 2002, 40(N12), 2483–2494.
29.
LiuH.-T.Effects of ambient turbulence on the decay of a trailing vortex wake. J. Aircraft, 1992, 29(N2), 255–263.
30.
HolzäpfelF.SteenM.Aircraft wake-vortex evolution in ground proximity: analysis and parameterization. AIAA J., 2007, 45(N1), 218–227.
31.
Burnham, D. C. and Hallock J. N. Measurements of wake vortices interacting with the ground. In AIAA Paper N98-0593, 1998.
32.
HolzäpfelF.HofbauerT.DarracqD.MoetH.GarnierF.Ferreira GagoC.Analysis of wake vortex decay mechanisms in the atmosphere. Aerosp. Sci. Technol., 2003, 7, 263–275.
33.
MoetH.LaporteF.ChevalierG.PoinsotT.Wave propagation in vortices and vortex bursting. Phys. Fluids, 2005, 17, 054109–054109.
34.
Holzäpfel, F. Misaka, T. and Hennemann, I. Wake-vortex topology, circulation, and turbulent exchange processes. In Proceedings of the AIAA Atmospheric and Space Environments Conference, Toronto, Canada, 2010, AIAA Paper 2010-7992.
35.
SaffmanP. G.Vortex dynamics, 1st edition, 1992 (Cambridge University Press, Cambridge).
36.
DhanakM. R.BernadinisB.The evolution of an elliptic vortex ring. J. Fluid Mech., 1981, 109, 189–216.
37.
SarpkayaT.Trailing vortices in homogeneous and density-stratified media. J. Fluid Mech., 1983, 136, 85–109.
38.
DelisiD. P.RobinsR. E.Short-scale instabilities in trailing wake vortices in a stratified fluid. AIAA J., 2000, 38(N10), 1916–1923.
39.
de Bruin, A. C. and Kannemans H. Analysis of NLR Cessna citation flight test data for flight test-1 in the AWIATOR project. AWIATOR, AW-NLR-113-010, NLR, 2004.
40.
SchwarzC. W.HahnK.-U.Full-flight simulator study for wake vortex hazard area investgation. Aerosp. Sci. Technol., 2006, 10, 136–143.
