CEAS Aeronautical Journal

, Volume 5, Issue 2, pp 109–125 | Cite as

Enhancement of aircraft wake vortex decay in ground proximity

Experiment versus Simulation
  • Anton Stephan
  • Frank Holzäpfel
  • Takashi Misaka
  • Reinhard Geisler
  • Robert Konrath
Original Paper

Abstract

Aircraft wake vortex evolution in ground proximity is investigated experimentally in a water towing tank, as well as numerically with wall-resolved large eddy simulation (LES). With these complementary instruments the enhancement of wake vortex decay by obstacles, introduced at the ground surface, is analyzed. The experimental methods include time-resolved stereo particle image velocimetry and vortex core visualization. For comparison with the experiment, the LES considers the turbulent wake of the strut, holding the towed aircraft model. Wake vortex trajectories and circulation decay are compared at different distances from the obstacle. Tracers are employed to visualize the obstacle’s effects on the vortex core, in LES and experiment. The experimentally obtained trajectories and decay characteristics are reproduced qualitatively by simulations, whereas the agreement is degraded at later times. Beyond that, the vortex dynamics, deduced from the LES results, help to understand the experimental observations. The obstacles trigger helical secondary vortex structures, propagating along the primary vortices. The observed propagation speed of the helical disturbance is fairly well predicted by the suggested simple model. It is shown that the obstacles significantly modify the vortex interaction with the ground and substantially accelerate vortex decay. Two neighboring obstacles lead to colliding disturbances that further enhance vortex decay rates.

Keywords

Wake vortex flow Ground effect Decay enhancement Large eddy simulation Towing tank Particle image velocimetry Obstacles 

List of symbols

Symbols

\(\varGamma\)

Circulation, m2/s

\(\varGamma_0\)

Initial vortex circulation, m2/s

\(\nu\)

Molecular viscosity, m2/s

\(\nu_{\rm t}\)

Turbulent viscosity, m2/s

ω

Vorticity, 1/s

ωxωyωz

Vorticity components, 1/s

ρ

Density, kg/m3

σ

Standard deviation

a

Radius of secondary vortex structure, m

AB

Parameters for strut wake turbulence model

b0

Initial vortex separation, m

C

Chord length, mm

CD

Drag coefficient, 1/m

d

Chord thickness, mm

Estrut

Turbulent kinetic energy of strut wake, Nm

\(E_\varGamma\)

Turbulent kinetic energy of the vortex, Nm

h0

Initial vortex height, m

LxLyLz

Dimensions, m

lstrut

Length of the strut, m

NxNyNz

Grid points

p

Pressure, N/m2

R

Curvature radius, m

\(Re_\varGamma\)

Vortex Reynolds number

\(Re_{\rm c}\)

Chord Reynolds number based on towing speed

rc

Vortex core radius, m

t

Time, s

t0

Time unit, s

U0

Towing speed, m/s

uiuvw

Velocity components, m/s

Uhel

Propagation speed of helix front, m/s

V0

Initial vortex descent speed, m/s

xixyz

Coordinates, m

\(\Updelta x\)

Distance to obstacle, m

Subscripts

0

Reference state

max

Maximum value

rms

Root mean square

hel

Helix

L

LES

ring

Ring

W

WSG

Superscripts

Deviation from reference state

*

Normalized with respect to vortex flow

+

Normalized by chord length

Abbreviations

DLR

German Aerospace Center

ICAO

International Civil Aviation Organization

LES

Large-eddy simulation

PIV

Particle image velocimetry

SVS

Secondary vortex structure

WSG

Wasser Schleppkanal Göttingen

WVAS

Wake vortex advisory system

References

  1. 1.
    Gerz, T., Holzäpfel, F., Bryant, W., Köpp, F., Ferch, M., Tafferner, A., Winckelmans, G.: Research towards a wake-vortex advisory system for optimal aircraft spacing. C. R. Phys. 6(4–5), 501–523 (2005)CrossRefGoogle Scholar
  2. 2.
    Gerz, T., Holzäpfel, F., Darracq, D.: Commercial aircraft wake vortices. Prog. Aerosp. Sci. 38(3), 181–208 (2002)CrossRefGoogle Scholar
  3. 3.
    Spalart, P.: Airplane trailing vortices. Annu. Rev. Fluid Mech. 30(1), 107–138 (1998)CrossRefMathSciNetGoogle Scholar
  4. 4.
    Critchley, J., Foot, P.: UK CAA wake vortex database: analysis of incidents reported between 1982 and 1990. Civil Aviation Authority, CAA Paper, vol. 91 (1991)Google Scholar
  5. 5.
    Holzäpfel, F., Steen, M.: Aircraft wake-vortex evolution in ground proximity: analysis and parameterization. AIAA J. 45, 218–227 (2007)CrossRefGoogle Scholar
  6. 6.
    Robins, R., Delisi, D.: Potential hazard of aircraft wake vortices in ground effect with crosswind. J. Aircr. 2, 201–206 (1993)CrossRefGoogle Scholar
  7. 7.
    Türk, L., Coors, D., Jacob, D.: Behavior of wake vortices near the ground over a large range of reynolds numbers. Aerosp. Sci. Technol. 3(2), 71–81 (1999) CrossRefMATHGoogle Scholar
  8. 8.
    Harvey, J., Perry, F.: Flowfield produced by trailing vortices in the vicinity of the ground. AIAA J. 9(8), 1659–1660 (1971) CrossRefGoogle Scholar
  9. 9.
    Dufresne, L., Baumann, R., Gerz, T., Winckelmans, G., Moet, H., Capart, R.: Large eddy simulation of wake vortex flows at very high reynolds numbers: a comparison of different methodologies. Technical Report, AWIATOR, D1.14-16 (2005)Google Scholar
  10. 10.
    Proctor, F.H., Hamilton, D.W., Han, J.: Wake vortex transport and decay in ground effect: Vortex linking with the ground. In: AIAA, 2000-0757, 38th Aerospace Sciences Meeting & Exhibit, Reno (2000)Google Scholar
  11. 11.
    Spalart, P., Strelets, M., Travin, A., Shur, M.: Modelling the interaction of a vortex pair with the ground. Fluid Dyn. 36(6), 899–908 (2001)CrossRefMATHMathSciNetGoogle Scholar
  12. 12.
    Stephan, A., Holzäpfel, F., Misaka, T.: (2013) Aircraft wake vortex decay in ground proximity—physical mechanisms and artificial enhancement. J. Aircr . http://arc.aiaa.org/doi/abs/10.2514/1.J051609. Accessed 19 June 2013
  13. 13.
    Coustols, E., Stumpf, E., Jaquin, L., Moens, F., Vollmers, H., Gerz, T.: Minimized wake: a collaborative research programme on aircraft wake vortices. AIAA Paper 2003-0938 (2003)Google Scholar
  14. 14.
    Stumpf, E.: Study of four-vortex aircraft wakes and layout of corresponding aircraft configurations. J. Aircr. 42, 722–730 (2005)CrossRefGoogle Scholar
  15. 15.
    Breitsamter, C.: Wake vortex characteristics of transport aircraft. Prog. Aerosp. Sci. 47, 89–134 (2011)CrossRefGoogle Scholar
  16. 16.
    Duponcheel, M., Lonfils, T., Bricteux, L., Winckelmans, G.: Simulations of three-dimensional wake vortices in ground effest using a fourth-order incompressible code. In: 7th National Congress on Theoretical and Applied Mechanics, Mons (2006)Google Scholar
  17. 17.
    Georges, L., Geuzaine, P., Duponchel, M., Bricteux, L., Lonfils, T., Winckelmans, G., Giovannini, A.: Technical report 3.1.1-3, les of two-vortex system in ground effect with and without wind. Technical Report, Université catholique de Louvain (UCL), Institut de Mécanique des Fluides de Toulouse (IMFT) (2005)Google Scholar
  18. 18.
    Delisi, D.P.: Laboratory measurements of the effect of ambient turbulence on trailing vortex evolution. In: 44th AIAA Aerospace Sciences Meeting and Exhibits, San Reno (2006)Google Scholar
  19. 19.
    Cottin, C., Desenfans, O.G.D., Winckelmans, G.: Towing-tank visualization of two-vortex systems in ground effect. Technical Report, FAR-Wake, Université Catholique de Louvain (UCL) (2007)Google Scholar
  20. 20.
    Konrath, R., Carmer, C., Schrauf, G., Schmidt, K., Winckelmans, G., Cottin, C., Desenfans, O.G.D., Cocle, R.: Dynamics and decay of spatially-evolving two- and four-vortex wakes near the ground. Technical Report, FAR-Wake project deliverable D 3.1.2 (2008)Google Scholar
  21. 21.
    Hah, C., Lakshminarayana, B.: Measurement and prediction of mean velocity and turbulence structure in the near wake of an airfoil. J. Fluid Mech. 115, 251–282 (1982)CrossRefGoogle Scholar
  22. 22.
    Zhang, Q., Lee, S.W., Ligrani, P.M.: Effects of surface roughness and freestream turbulence on the wake turbulence structure of a symmetric airfoil. Phys. Fluids 16(6), 2044–2053 (2004)CrossRefGoogle Scholar
  23. 23.
    Manhart, M.: A zonal grid algorithm for dns of turbulent boundary layer. Comput. Fluids 33(3), 435–461 (2004)CrossRefMATHGoogle Scholar
  24. 24.
    Meneveau, C., Lund, T.S., Cabot, W.H.: A lagrangian dynamic subgrid-scale model of turbulence. J. Fluid Mech. 319, 353–385 (1996)CrossRefMATHGoogle Scholar
  25. 25.
    Holzäpfel, F.: Adjustment of subgrid-scale parametrizations to strong streamline curvature. AIAA J. 42(7), 1369–1377 (2004) CrossRefGoogle Scholar
  26. 26.
    Shen, S., Ding, F., Han, J., Proctor, F.H.: Numerical modeling studies of wake vortices: real case simulations. In: 37th AIAA Aerospace Sciences Meeting and Exhibit. Reno, Nevada, USA (1999)Google Scholar
  27. 27.
    Hokpunna, A., Manhart, M.: Compact fourth-order finite volume method for numarical solutions of Navier–Stokes equations on staggered grids. J. Comput. Phys. 229(20), 7545–7570 (2010)CrossRefMATHMathSciNetGoogle Scholar
  28. 28.
    Misaka, T., Holzäpfel, F., Gerz, T.: Wake evolution of wing-body configuration from roll-up to vortex decay. In: 50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Nashville, Tennessee, USA., 2012-0428, pp. 1–15 (2012)Google Scholar
  29. 29.
    Béchara, W., Bailly, C., Lafon, P.: Stochastic approach to noise modeling for free turbulent flows. AIAA J. 32(3), 455–463 (1994)CrossRefMATHGoogle Scholar
  30. 30.
    de Bruin, A., Winckelmans, G.: Cross-flow kinetic energy and core size growth of analytically defined wake vortex pairs. Technical Report, NLR-CR-2005-412, NLR (2005)Google Scholar
  31. 31.
    Holzäpfel, F., Hofbauer, T., Darracq, D., Moet, H., Garnier, F., Ferreira Gago, C.: Analysis of wake vortex decay mechanisms in the atmosphere. Aerosp. Sci. Technol. 7, 263–275 (2003)CrossRefMATHGoogle Scholar
  32. 32.
    Misaka, T., Holzäpfel, F., Hennemann, I., Gerz, T., Manhart, M., Schwertfirm, F.: Vortex bursting and tracer transport of a counter-rotating vortex pair. Phys. Fluids 24, 025,104-1–025,104-21 (2012)Google Scholar
  33. 33.
    Holzäpfel, F.: Probabilistic two-phase wake vortex decay and transport model. J. Aircr. 40(2), 323–331 (2003)CrossRefGoogle Scholar
  34. 34.
    Konrath, R., Pallek, D., Mattner, H., v. Cramer C.: Analysis of flow field measurements obtained in a large tow tank regarding the decay of wake vortices in the far-field for two- and four-vortex systems. In: AIAA-Paper 2009-342, 47th AIAA Aerospace Science Meeting, Orlando (Florida) (2009)Google Scholar
  35. 35.
    Holzäpfel, F., Gerz, T., Baumann, R.: The turbulent decay of trailing vortex pairs in stably stratified environments. Aerosp. Sci. Technol. 5(2), 95–108 (2001)CrossRefMATHGoogle Scholar
  36. 36.
    Moet, H., Laporte, F., Chevalier, G., Poinsot, T.: Wave propagation in vortices and vortex bursting. Phys. Fluids 17, 054,109 (2005)Google Scholar
  37. 37.
  38. 38.
  39. 39.
    Lamb, H.: Hydrodynamics. Cambridge University Press, London (1957)Google Scholar

Copyright information

© Deutsches Zentrum für Luft- und Raumfahrt e.V. 2013

Authors and Affiliations

  • Anton Stephan
    • 1
  • Frank Holzäpfel
    • 1
  • Takashi Misaka
    • 1
  • Reinhard Geisler
    • 2
  • Robert Konrath
    • 2
  1. 1.Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR)OberpfaffenhofenGermany
  2. 2.Institut für Aerodynamik und Strömungstechnik, Deutsches Zentrum für Luft- und Raumfahrt (DLR)GöttingenGermany

Personalised recommendations