an efficient approach for determining the flutter characteristics of rotor blades for multi-megawatt...
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![Page 1: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/1.jpg)
An efficient Approach for Determining the
Flutter Characteristicsof Rotor Blades for
Multi-Megawatt Wind TurbinesEWEC 2006 - Presentation No. 627
CS4: Aerodynamics, Aeroelasticity and LoadsDipl.-Ing. Raphael Haas
EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH, Berlin
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An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Introduction – Problem definitionIntroduction – Problem definitionEUROS manufactures blades ranging from 10m to 56m for WEC from 100kW to 5.0MWTrend in development of large rotor blades:longer, lighter and narrower blades.Aeroelastically critical designs
Risk of flutter
![Page 3: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/3.jpg)
An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
What is flutter ?What is flutter ?
Flutter – an explanation:resonant (unstable) motion interaction of structural mass, stiffness, and aerodynamic forcesusually present above some limiting (rotor) speed.
![Page 4: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/4.jpg)
An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
OverviewOverviewSystem equation and structural modelUnsteady aerodynamics – GreenbergUnsteady aerodynamics – LoewyReduction of system sizeResults – Development of dampingResults – Influencing Factors
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An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
System equationSystem equation
Matrices:M: mass matrixD: damping matrixK: stiffness matrix
azgazgelaat pppxKKKKxDxMM
pxKxDxM
)()()(
Inidices:t: inertia mass termsa: aerodynamic termsel: elastic stiffness termsg: pretension stiffening termsz: centrifugal stiffening terms
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An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Structural model (1)Structural model (1)
![Page 7: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/7.jpg)
An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Structural model (2)Structural model (2)
![Page 8: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/8.jpg)
An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
)t(i0 exx
Unsteady Aerodynamics–Unsteady Aerodynamics–Greenberg(1)Greenberg(1)
![Page 9: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/9.jpg)
An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Unsteady Aerodynamics–Unsteady Aerodynamics–Greenberg(2)Greenberg(2)
![Page 10: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/10.jpg)
An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Unsteady Aerodynamics – Loewy Unsteady Aerodynamics – Loewy (1)(1)
Pict. source: Loewy: „A Two-Dimesional Approximation to the Unsteady Aerodynamics of Rotary Wings“Journal of the Aeronautical Sciences, Vol. 24, No. 2, pp. 81-92, Feb. 1957.
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An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Unsteady Aerodynamics – Loewy Unsteady Aerodynamics – Loewy (2)(2)
![Page 12: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/12.jpg)
An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Static CondensationReduction of system size (1)Reduction of system size (1)
Pict. source: Gasch: „Strukturdynamik, Band 2: Kontinua und ihre Diskretisierung.“ Springer. Berlin. 1989.
![Page 13: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/13.jpg)
An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Modal CondensationReduction of system size (2)Reduction of system size (2)
Pict. source: Gasch: „Strukturdynamik, Band 2: Kontinua und ihre Diskretisierung.“ Springer. Berlin. 1989.
![Page 14: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/14.jpg)
An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Example blade EU80:Length: 39mWeight: 6.5 tons
DiagramsFirst order elastic beamHalf torsional stiffness (2nd o. beam)Full torsional stiffness (2nd o. beam)
Results-Trend of damping Results-Trend of damping coefficients(1)coefficients(1)
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An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Damping coefficients vs. Rotor speed, first order elastic beam.
Results-Trend of damping Results-Trend of damping coefficients(2)coefficients(2)
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An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Damping vs. rotor speed, 2nd order el. Beam, full torsional stiffness.
Results-Trend of damping Results-Trend of damping coefficients(3)coefficients(3)
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An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Damping vs. rotor speed, 2nd order el. Beam, half torsional stiffness.
Results-Trend of damping Results-Trend of damping coefficients(4)coefficients(4)
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An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Results – Influencing FactorsResults – Influencing Factors
Higher torsional stiffness significantly shifts the flutter onset rotor speed
Usage of a second order FEM blade model is mandatory
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An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Present status and outlookPresent status and outlook
Natural frequencies and modeshapes evaluated for each blade
Fast and easy to use tool
Integration into an iterative design loop
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An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
![Page 21: An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind Turbines EWEC 2006 - Presentation No. 627 CS4:](https://reader038.vdocuments.mx/reader038/viewer/2022103103/570491c91a28ab14218dc8c6/html5/thumbnails/21.jpg)
An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt An efficient Approach for Determining the Flutter Characteristics of Rotor Blades for Multi-Megawatt Wind TurbinesWind Turbines
Raphael Haas – EUROS Entwicklungsgesellschaft für Windkraftanlagen mbH – Berlin – Germany
Natural frequ. vs. rotor speed, cons. system – no aerodynamic loads.Natural frequ. vs. rotor speed, 2nd order el. Beam, no returning wake.Damping vs. rotor speed, 2nd order el. Beam, no returning wake.
Results – No returning wakeResults – No returning wake
azgazgelaat pppxKKKKxDxMM
pxKxDxM
)()()(