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

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.

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, = Uc


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


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringMcGill UniversityMontrealCanada

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