Presentación de PowerPointAEROELASTIC TOOLS FOR 2D AEROFOILS WITH VARIABLE GEOMETRY FOR WIND TURBINE APPLICATIONS
A. González1*, X. Munduate1, R. Palacios2, J.M.R. Graham2
Wind Energy Department, CENER, Ciudad de la Innovación, 7, Sarriguren, Spain, 31621
Department of Aeronautics, Imperial College, London, SW72AZ, UK
*e-mail: agonzalez@cener.com
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Introduction
Effective load control:
Classical thin aerofoil theory:
Engineering tools of with very good computational efficiency for preliminary purposes
In-house code AdaptFoil1D (validated)
In-house code AdaptFoil2D (currently in development)
CFD:
Detailed representation of aerofoil and flow, but much higher computational cost
CENER
ICL
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Based on the work of Peters *
Attached flow
Prescribed deformation:
Large 3-dof rigid-body motion allowed (small effective angle of attack)
Modifications of the meanline geometry under the small displacements assumption
Body dynamics:
3-dof system of springs and dampers at a single point for rigid body motion
Additional deformation of LE or TE flap, using a static Euler-Bernoulli approach
* Peters, D.A., Johnson, M.J., Finite-State airloads for deformable aerofoils on fixed and rotating wings, AD-Vol. 44, Aeroelasticity and Fluid Structure Interaction Problems.
* Peters, D.A., Hsieh, A., and Torrero, A., A state-space airloads theory for flexible aerofoils, In Proceedings of the American Helicopter Society, 62nd Annual Forum, Phoenix, AZ, USA, 2006.
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Panel methods * - Surface panel code for a thick aerofoil section
Piecewise constant doublets and sources in each panel
The Neumann and Dirichlet conditions are combined
Kutta condition: tangential velocity difference between the upper and lower panels at the TE = shed vorticity
The wake is a doublet panel attached to the TE, transformed into discrete vortices downstream
Free wake and time-stepping method to calculate the wake roll-up
Wake vortices implemented with a lamb vortex core to avoid numerical problems
Attached flow
* Katz, J., Plotkin, A., Low-speed aerodynamics, Cambridge Aerospace Series, 2001.
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Results
Excellent agreement between AdaptFoil2D and XFoil *
* Drela, M., XFOIL: An analysis and design system for low Reynolds number airfoils, Conference on Low Reynolds Number Airfoil Aerodynamics, University of Notre Dame, 1989.
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Results
2. Unsteady aerodynamics
Flat plate (NACA 0003) performing a sudden acceleration, α=5º. Comparison between AdaptFoil2D, AdaptFoil1D and a lumped and discrete vortex methods *
Excellent comparison. Convergence to the steady values. Inaccuracies for lumped vortex method.
* Katz, J., Plotkin, A., Low-speed aerodynamics, Cambridge Aerospace Series, 2001.
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Results
Flat plate (NACA 0003) performing a sudden acceleration, α=5º
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Results
NACA 0012, combined pitching and oscillating TE flap
(specific case: ωα=0.021, ωβ=0.042, δ=59º) …compared with experimental data *
Good overall agreement for a combined pithing and oscillating TE flap
* Krzysiak, A., Narkiewicz, J., Aerodynamic loads on aerofoil with trailing-edge flap pitching with different frequencies, Journal of aircraft, 43(2):407-418, 2006.
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Results
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Results
3. Aeroelastic modelling
Plunge-pitch flat plate (NACA 0003): aerofoil radius of gyration (rα)2=0.25, aerodynamic centre a=-0.3, inverse mass ratio, κ=0.05) …compared with data given by Zeiler *
Good agreement. Divergence not calculated by Zeiler. Minor deviations for χα=0.2 at high ωh/ ωα
* Zeiler, T.A., Results of Theodorsen and Garrick revisited, Journal of Aircraft Engineering Notes, 37(5):918-920, 2000.
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Development and validation of AdaptFoil2D, new panel code for deformable aerofoils
Mostly successful validation
Steady and unsteady aerodynamic and aeroelastic computations
Fast and reliable tool for evaluation of the aeroelastic performance of 2D aerofoils
AdaptFoil1D and AdaptFoil2D are suitable for design of aerodynamic control on wind turbine blades
Further work:
separated flow and dynamic stall conditions
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www.cener.com
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