Experiments in Fluids

, Volume 50, Issue 6, pp 1671–1684 | Cite as

Lift enhancement and flow structure of airfoil with joint trailing-edge flap and Gurney flap

  • T. LeeEmail author
  • Y. Y. Su
Research Article


The impact of Gurney flaps (GF), of different heights and perforations, on the aerodynamic and wake characteristics of a NACA 0015 airfoil equipped with a trailing-edge flap (TEF) was investigated experimentally at Re = 2.54 × 105. The addition of the Gurney flap to the TEF produced a further increase in the downward turning of the mean flow (increased aft camber), leading to a significant increase in the lift, drag, and pitching moment compared to that produced by independently deployed TEF or GF. The maximum lift increased with flap height, with the maximum lift-enhancement effectiveness exhibited at the smallest flap height. The near wake behind the joint TEF and GF became wider and had a larger velocity deficit and fluctuations compared to independent GF and TEF deployment. The Gurney flap perforation had only a minor impact on the wake and aerodynamics characteristics compared to TEF with a solid GF. The rapid rise in lift generation of the joint TEF and GF application, compared to conventional TEF deployment, could provide an improved off-design high-lift device during landing and takeoff.


Particle Image Velocimetry Pitching Moment Particle Image Velocimetry Image Particle Image Velocimetry System Flap Perforation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols


Wing span


Airfoil chord


Section drag coefficient


Section lift coefficient


Maximum lift coefficient


Lift-curve slope


Section pitching moment coefficient about ¼-chord


Peak pitching moment coefficient


Surface pressure coefficient


Perforation hole diameter


Gurney flap height


Reynolds number, = U c


Mean streamwise velocity


Streamwise velocity fluctuation


Freestream velocity

x, y, z

Streamwise, transverse and spanwise direction


Angle of attack


Static-stall angle


Zero-lift angle


Trailing-edge flap deflection


Flap porosity


Mean streamwise vorticity


Kinematic viscosity



This work was supported by the Natural Science and Engineering Research Council (NSERC) of Canada. L.S. Ko is thanked for his help with the PIV experiment.


  1. Althaus D, Wortmann FX (1981) Stuttgarter Profilkatalog I. Published by Vieweg F and Verlag SGoogle Scholar
  2. Chow R, van Dam CP (2006) Unsteady computational investigations of deploying load control microtabs. J Aircr 43(5):1458–1469CrossRefGoogle Scholar
  3. Ewald BFR (1998) Wind tunnel wall corrections. AGARDograph 336, North Atlantic Treaty OrganizationGoogle Scholar
  4. Gai SL, Palfrey R (2003) Influence of trailing-edge flow control on airfoil performance. J Aircr 40(2):332–337CrossRefGoogle Scholar
  5. Gerontakos P, Lee T (2006a) Oscillating wing loadings with trailing-edge strips. J Aircr 43(2):428–436CrossRefGoogle Scholar
  6. Gerontakos P, Lee T (2006b) Active dynamic-stall flow control via a trailing-edge flap. AIAA J 44(3):469–480CrossRefGoogle Scholar
  7. Gerontakos P, Lee T (2008) PIV investigation of flow over unsteady airfoil with trailing-edge strip. Exp Fluids 44(4):539–556CrossRefGoogle Scholar
  8. Giguere P, Duma G, Lemay J (1997) Gurney flap scaling for optimum lift-to-drag ratio. AIAA J 35(12):1888–1890CrossRefGoogle Scholar
  9. Jang CS, Ross JC, Cummings RM (1998) Numerical investigation of an airfoil with a Gurney flap. Aircr Des 1(2):75–88CrossRefGoogle Scholar
  10. Jeffrey D, Zhang X, Hurst DW (2000) Aerodynamics of Gurney flaps on a single-element high-lift wing. J Aircr 37(2):295–301CrossRefGoogle Scholar
  11. Kentfield JAC, Clavelle EJ (1993) The flow physics of Gurney flaps, devices for improving turbine blade performance. Wind Eng 17(1):24–34Google Scholar
  12. Lee T, Basu S (1998) Measurement of unsteady boundary layer developed on an oscillating airfoil using multiple hot-film sensors. Exp Fluids 25:108–117CrossRefGoogle Scholar
  13. Lee T, Ko LS (2009) PIV investigation of flowfield behind perforated Gurney-type flaps. Exp Fluids 46(6):1005–1019MathSciNetCrossRefGoogle Scholar
  14. Li Y, Wang JJ, Zhang P (2003) Influences of mounting angles and locations on the effects of Gurney flaps. J Aircr 40(3):494–498CrossRefGoogle Scholar
  15. Liebeck RH (1978) Design of subsonic airfoils for high lift. J Aircr 15(9):547–561CrossRefGoogle Scholar
  16. Liu T, Monteford J (2007) Thin-airfoil theoretical interpretation for Gurney flap lift enhancement. J Aircr 44(2):667–671CrossRefGoogle Scholar
  17. Maughmer MD, Bramesfeld G (2008) Experimental investigation of Gurney flaps. J Aircr 45(6):2062–2067CrossRefGoogle Scholar
  18. Meyer R, Hage W, Bechert DW, Schatz M, Thiele F (2006) Drag reduction on Gurney flap by three-dimensional modifications. J Aircr 43(1):132–140CrossRefGoogle Scholar
  19. Moffat RJ (1985) Describing the uncertainties in experimental results. Exp Therm Fluid Sci 1:3–17CrossRefGoogle Scholar
  20. Myose R, Papadakis M, Heron I (1998) Gurney flap experiments on airfoils, wings, and reflection plane model. J Aircr 35(2):206–211CrossRefGoogle Scholar
  21. Neuhart DH, Pendergraft OC (1988) A water tunnel study of Gurney flaps. NASA TM-4071Google Scholar
  22. Perry ML, Mueller TJ (1985) Leading and trailing edge flaps on a low Reynolds number airfoil. J Aircr 24(9):763–770Google Scholar
  23. Pope A, Rae WH (1984) Low speed wind tunnel testing. Wiley, New YorkGoogle Scholar
  24. Rennie R, Jumper EJ (1996) Experimental measurements of dynamic control surface effectiveness. J Aircr 33(5):880–887CrossRefGoogle Scholar
  25. Smith AMO (1975) High-lift aerodynamics. J Aircr 12(6):501–530CrossRefGoogle Scholar
  26. Stanewsky E (2001) Adaptive wing and flow control technology. Prog Aerosp Sci 37:583–667CrossRefGoogle Scholar
  27. Storms BL, Jang CS (1994) Lift enhancement of an airfoil using a Gurney flap and vortex generators. J Aircr 31(3):542–547CrossRefGoogle Scholar
  28. Tang D, Dowell EH (2007) Aerodynamic loading of an airfoil with an oscillating Gurney flap. J Aircr 44(4):245–1257CrossRefGoogle Scholar
  29. Theodorsen T (1935) General theory of aerodynamic instability and the mechanism of flutter. NACA TR496Google Scholar
  30. Traub LW, Miller AC, Rediniotis O (2006) Preliminary parametric study of Gurney-flap dependencies. J Aircr 43(4):1242–1244CrossRefGoogle Scholar
  31. Troolin DR (2009) Private communication. dtroolin@tsi.comGoogle Scholar
  32. Troolin DR, Longmire EK, Lai WT (2006) Time resolved PIV analysis of flow over a NACA 0015 airfoil with Gurney flap. Exp Fluids 41:241–254CrossRefGoogle Scholar
  33. van Dam CP, Yen DT, Vijgen PMHW (1999) Gurney flap experiments on airfoil and wings. J Aircr 36(2):484–486CrossRefGoogle Scholar
  34. Vipperman JS, Clark RL, Conner M, Dowell EH (1998) Experimental active control of a typical section using a trailing-edge flap. J Aircr 35(2):224–229CrossRefGoogle Scholar
  35. Wang JJ, Li YC, Choi K-S (2008) Gurney flap-lift enhancement, mechanism and applications. Prog Aerosp Sci 44:22–47CrossRefGoogle Scholar
  36. Yee K, Joo W, Lee D-H (2007) Aerodynamic performance analysis of a Gurney flap for rotorcraft application. J Aircr 44(3):1003–1014CrossRefGoogle Scholar
  37. Zerihan J, Zhang X (2001) Aerodynamics of Gurney flaps on a wing in ground effect. AIAA J 39(5):772–780CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringMcGill UniversityMontrealCanada

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