Suppressing Vortex Induced Vibrations of Wind Turbine Blades with Flaps

Horcas, Sergio González; Madsen, Mads H. Aa.; Sørensen, Niels N.; Zahle, Frederik

doi:10.1007/978-3-030-11887-7_2

Cited by 9 publications

(5 citation statements)

References 11 publications

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“…11, showing the tip displacement of the blade, the drag coefficients reach 4.5-5.30 before achieving similar damping as the FSI-CFD simulation. This value fits well with the drag coefficients stated by Greaves (2013) for the calibration with 2D CFD simulations of 5.30 and 4.45 for 1 and 2 m amplitudes, albeit on another profile. Taking a close look at the first few oscillations of the FSI-BET simulations shown in Fig.…”

Section: Drag Coefficient Calibrationsupporting

confidence: 86%

“…The two codes are coupled, in a two-way manner, through the Python framework HAWC2CFD, originally created by Heinz (Heinz, 2013) and further developed by Horcas (González Horcas et al, 2019).…”

Section: Fsi Frameworkmentioning

confidence: 99%

“…These tests are especially relevant, as wind turbine blade design optimization continuously moves the limit of what is possible in regards to saving material and lowering the levelized cost of energy (LCoE). When conducting fatigue tests on wind turbine blade designs, the standard procedure is to excite the blade in the resonance frequency for 2×10 6 -10×10 6 cycles in flapwise and edgewise directions or both simultaneously using biaxial forcing (White, 2004;Greaves et al, 2011;Greaves, 2013;Post, 2016). Blades are usually anchored in a horizontal position by means of steel bolts connecting the root to a test rig, whereas the excitation is enforced using translating or rotating mass exciters or, more traditionally, by forced motions using ground-based hydraulic actuators.…”

Section: Introductionmentioning

confidence: 99%

“…This is needed, since codes based on Blade Element Theory (BET) aerodynamic models do not account for the vortices created. This phenomenon was studied by Greaves, who calibrated the drag coefficient to fit the drag force to two-dimensional computational fluid dynamics (CFD) simulations made by The National Renewable Energy Centre (Narec) in the UK (Greaves, 2013). The CFD study was limited to one airfoil, oscillating at 1 Hz in amplitudes of 1 and 2 m. In the study, Greaves found that a drag coefficient for a 90 • angle (flapwise motion) should be set to approximately 5.3 and 4.45 at 1 and 2 m amplitude, respectively, to account for the added damping.…”

Section: Introductionmentioning

confidence: 99%

“…Confinement from walls, floor or ceiling was included neither in the aforementioned studies by Greaves (2013) using CFD nor in the experiments by Woolam (1968). In laboratories, the blades are positioned horizontally, and during fatigue tests they oscillate in a fashion that brings the blade tip close to the floor.…”

Section: Introductionmentioning

confidence: 99%

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Investigations of aerodynamic drag forces during structural blade testing using high-fidelity fluid–structure interaction

et al. 2020

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Abstract. Aerodynamic loads need to be known for planning and defining test loads beforehand for wind turbine blades that are tested for fatigue certifications. It is known that the aerodynamic forces, especially drag, are different for tests and operation, due to the entirely different flow conditions. In test facilities, a vibrating blade will move in and out of its own wake, increasing the drag forces on the blade. This is not the case in operation. To study this special aerodynamic condition present during experimental tests, numerical simulations of a wind turbine blade during pull–release tests were conducted. High-fidelity three-dimensional computational fluid dynamics methods were used throughout the simulations. In this way, the fluid mechanisms and their impact on the moving blade are clarified, and through the coupling with a structural solver, the fluid–structure interaction is studied. Results are compared to actual measurements from experimental tests, verifying the approach. It is found that the blade experiences a high drag due to its motion towards its own whirling wake, resulting in an effective drag coefficient of approximately 5.3 for the 90∘ angle of attack. This large drag coefficient was implemented in a fatigue test load simulation, resulting in a significant decrease in bending moment along the blade, leading to less load being applied than intended. The confinement from the test facility did not impact this specific test setup, but simulations with longer blades could possibly yield different conclusions. To the knowledge of the authors, this investigation, including three-dimensional effects, structural coupling and confinement, is the first of its kind.

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Section: Drag Coefficient Calibrationsupporting

confidence: 86%

Section: Fsi Frameworkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigations of aerodynamic drag forces during structural blade testing using high-fidelity fluid–structure interaction

et al. 2020

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Fluid–structure interaction simulations of a wind turbine rotor in complex flows, validated through field experiments

2021

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Aeroelastic simulations of a 2.3 MW wind turbine rotor operating in different complex atmospheric flows are conducted using high fidelity fluid–structure interaction (FSI) simulations. Simpler blade element momentum (BEM) theory based simulations are likewise conducted for comparison, and measurements from field experiments are used for validation of the simulations. Good agreement is seen between simulated and measured forces. It is found that for complex flows, BEM‐based simulations predict similar forces as computational fluid dynamics (CFD)‐based FSI, however with some distinct discrepancies. Firstly, stall is predicted for a large part of the blade using BEM‐based aerodynamics, which are not seen in either FSI simulations or measurements in the case of a high shear. This leads to a more dynamic structural response for BEM‐based simulations than for FSI. For a highly yawed and sheared flow case, the BEM‐based simulations overpredict outboard forces for a significant part of the rotation. This emphasizes the need of validation of BEM‐based simulations through higher fidelity methods, when considering complex flows. Including flexibility in simulations shows only little impact on the considered rotor for both FSI‐ and BEM‐based simulations. In general, the loading of the blades increases slightly, and the rotor wake is almost identical for stiff and flexible FSI simulations.

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The Other Navy Seals: Seal Whiskers as a Bio-inspired Model for the Reduction of Vortex-Induced Vibrations

Murphy

Martin

Franck

et al. 2021

Recent Trends in Naval Engineering Research

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Suppressing Vortex Induced Vibrations of Wind Turbine Blades with Flaps

Cited by 9 publications

References 11 publications

Investigations of aerodynamic drag forces during structural blade testing using high-fidelity fluid–structure interaction

Investigations of aerodynamic drag forces during structural blade testing using high-fidelity fluid–structure interaction

Fluid–structure interaction simulations of a wind turbine rotor in complex flows, validated through field experiments

The Other Navy Seals: Seal Whiskers as a Bio-inspired Model for the Reduction of Vortex-Induced Vibrations

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