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
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List of symbols
Section drag coefficient
Section lift coefficient
Maximum lift coefficient
Section pitching moment coefficient about ¼-chord
Peak pitching moment coefficient
Surface pressure coefficient
Perforation hole diameter
Gurney flap height
Reynolds number, = U∞c/ν
Mean streamwise velocity
Streamwise velocity fluctuation
x, y, z
Streamwise, transverse and spanwise direction
Angle of attack
Trailing-edge flap deflection
Mean streamwise vorticity
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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.
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