Computational Study of the Risø-B1-18 Airfoil with a Hinged Flap Providing Variable Trailing Edge Geometry

Abstract

A comprehensive computational study, in both steady and unsteady flow conditions, has been carried out to investigate the aerodynamic characteristics of the Risø-B1-18 airfoil equipped with variable trailing edge geometry as produced by a hinged flap. The function of such flaps should be to decrease fatigue-inducing oscillations on the blades. The computations were conducted using a 2D incompressible RANS solver with a k-w turbulence model under the assumption of a fully developed turbulent flow. The investigations were conducted at a Reynolds number of Re = 1.6 · 10⁶. Calculations conducted on the baseline airfoil showed excellent agreement with measurements on the same airfoil with the same specified conditions. Furthermore, a more widespread comparison with an advanced potential theory code is presented. The influence of various key parameters, such as flap shape, flap size and oscillating frequencies, was investigated so that an optimum design can be suggested for application with wind turbine blades. It is concluded that a moderately curved flap with flap chord to airfoil curve ratio between 0.05 and 0.10 would be an optimum choice.

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References

Abbott

I.H.

von Doenhoff

A.E.

, Theory of Wing Sections, 1st ed. Dover Publications, Inc., 1959.

Danish Standard, Dansk Ingeniørforenings og Ingeniør-Sammenslutningens Norm for last of sikkerhed for vindmøllekonstruktioner, 1. udgave, Dansk Standard, Teknisk Forlag, maj 1992.

Depailler

Friedmann

P.P.

, Alleviation of Dynamic Stall Induced Vibrations using Actively Controlled Flaps, American Helicopter Society 58th Annual Forum, Montreal, Canada, June, 11–13, 2002.

Feszty

Gillies

E.A.

Vezza

, Alleviation of Airfoil Dynamic Stall Moments via Trailing-Edge-Flap Flow Control, AIAA Journal, vol. 42, No. 1, January, 2004.

Fuglsang

Bak

Gaunaa

Antoniou

, Wind tunnel Tests of Risø-B1–18 and Risø-B1–24, Risø-R-1375(EN), Risø National Laboratories, Roskilde, Denmark, January, 2003.

Gaunaa

, Unsteady 2D Potential-flow Forces on a Variable Geometry Airfoil Undergoing Arbitrary Motion, Risø-R-1478(EN), Risø National Laboratory, Roskilde, Denmark, To be published December 2004.

Geissler

Sobieczky

Vollmers

, Numerical Study of the Unsteady Flow on a Pitching Airfoil with Oscillating Flap, 24th European Rotorcraft Forum, Marseilles, France, 1998.

Han

, Aeroelastic stability and response of a wind turbine blade with trailing edge flaps, Wind Energy. Proceedings of the 1998 Twentieth BWEA Wind Energy Conference, 1998.

Hansen

M.O.L.

, Aerodynamics of Wind Turbines, James & James, 2000.

10.

Hariharan

Leishman

J.G.

, Unsteady Aerodynamics of a Flapped Airfoil in Subsonic Flow by Indicial Concepts, Journal of Aircraft, vol. 33, No. 5, September-October 1996.

11.

Kim

J-S.

Smith

E.C.

Wang

K.W.

, Active Load Control of an Articulated Composite Rotor Blade via Dual Trailing Edge Flaps, AIAA 2003–1543, The American Institute of Aeronautics and Astronautics, Inc. 2003.

12.

Leishman

J.G.

, Unsteady Lift of a Flapped Airfoil by Indicial Concepts, Journal of Aircraft, vol. 31, No. 2, March–April 1994.

13.

Leishman

J.G.

, Principles of Helicopter Aerodynamics, Cambridge Aerospace Series, Cambridge University Press, 2000.

14.

Leishman

J.G.

, Challenges in Modeling the Unsteady Aerodynamics of Wind Turbines, AIAA 2002–0037, 21th ASME Wind Energy Symposium and the 40th AIAA Aerospace Science Meeting, Reno, NV, January 14–17, 2002.

15.

Menter

F. R.

, Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications, AIAA Journal, vol. 32, No. 8, August 1994.

16.

Milgram

Chopra

, Dynamics of an Actively Controlled Plain Trailing Edge Flap System for a Modern Bearingless Rotor, 23rd European Rotorcraft Forum, Dresden, Germany, September 16–18, 1997.

17.

Michelsen

J. A.

, Basis3D – a Platform for Development of Multiblock PDE Solvers, Tech. Report AFM 92–05, Technical University of Denmark, 1992.

18.

Michelsen

J.A.

, Block structured Multigrid solution of 2D and 3D elliptic PDE's, Tech. Report AFM 94–06, Technical University of Denmark, 1994.

19.

Milgram

Chopra

, A Parametric Design Study for Actively Controlled Trailing Edge Flaps, Journal of the American Helicopter Society, 43 2, April, 1998.

20.

Munk

M.M.

, General Theory of Thin Wing Sections, National Advisory Committee for Aeronutics, Report no. 142, 1922.

21.

Øye

, Instationære Aerodynamiske Kræfter på Todimensionelt Vingeprofil, AFM Notat 81–05, Technical University of Denmark (DTU), November 1981.

22.

Sørensen

N.N.

, General Purpose Flow Solver Applied to Flow over Hills, Risø-R-827(EN), Risø National Laboratory, Roskilde, Denmark, June 1995.

23.

Sørensen

N.N.

, HypGrid2D a 2-D Mesh Generator, Risø-R-1035(EN), Risø National Laboratory, Roskilde, Denmark, March 1998.

24.

Theodorsen

, General Theory of Aerodynamic Instability and the Mechanism of Flutter, National Advisory Committee for Aeronautics, Report no. 496, 1935.

25.

Troldborg

, Computational Study of the Risø-B1–18 Airfoil Equipped with Actively Controlled Trailing Edge Flaps, Master thesis, Report No.: MEK-FM-EP-2004-09, September, 2004.

26.

van der Wall

B.G.

Geissler

, Experimental and Numerical Investigations on Steady and Unsteady Behavior of a Rotor Airfoil with Piezoelectric Trailing Edge Flap, American Helicopter Society 55th Annual Forum, Montreal, Canada, May 25–27, 1999.

27.

Veers

P.S.

, Three-Dimensional Wind Simulation, SAND88–0152·UC-261, Sandia National Laboratories, Albuquerque, New Mexico, March, 1988.