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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

Abstract

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.

Keywords

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

b

Wing span

c

Airfoil chord

Cd

Section drag coefficient

Cl

Section lift coefficient

Cl,max

Maximum lift coefficient

Cl

Lift-curve slope

Cm

Section pitching moment coefficient about ¼-chord

Cm,peak

Peak pitching moment coefficient

Cp

Surface pressure coefficient

d

Perforation hole diameter

h

Gurney flap height

Re

Reynolds number, = U c

u

Mean streamwise velocity

u

Streamwise velocity fluctuation

U

Freestream velocity

x, y, z

Streamwise, transverse and spanwise direction

α

Angle of attack

αss

Static-stall angle

αzl

Zero-lift angle

δ

Trailing-edge flap deflection

σ

Flap porosity

ζ

Mean streamwise vorticity

ν

Kinematic viscosity

Notes

Acknowledgments

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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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringMcGill UniversityMontrealCanada

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