Some Effect of Large Blade Deflections on Aeroelastic Stability

Kallesøe, Bjarne Skovmose; Hansen, Morten Hartvig

doi:10.2514/6.2009-839

Cited by 12 publications

(11 citation statements)

References 3 publications

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“…Analysis of the edgewise mode shape further shows that geometric coupling due to prebending and load deflection has a significant influence on the edgewise mode shape. An effect of blade deflection on the edgewise mode shape has also been observed by Kallesøe and Hansen (2009).…”

Section: Discussionmentioning

confidence: 65%

“…The critical inflow speed increases for edge-twist to stall coupled blades. The formation of an edge-twist flutter mode, where the torsional component of the edgewise mode becomes large enough and in phase with the flapwise velocity has previously been reported by Kallesøe and Hansen (2009) and Stäblein et al (2016a).…”

Section: Discussionmentioning

confidence: 99%

“…The flutter speed of the coupled blade is moderately lower than of the uncoupled blade. Kallesøe and Hansen (2009) investigate the effect of finite steady-state blade deflections on the aeroelastic stability of the NREL 5 MW Reference Wind Turbine (Jonkman et al, 2009) using an eigenvalue approach. A geometric nonlinear finiteelement beam model and aerodynamic forces obtained from blade element momentum theory are used to find a steadystate equilibrium of the turbine.…”

Section: A R Stäblein Et Al: Modal Properties and Stability Of Benmentioning

confidence: 99%

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Modal properties and stability of bend–twist coupled wind turbine blades

2017

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Abstract.Coupling between bending and twist has a significant influence on the aeroelastic response of wind turbine blades. The coupling can arise from the blade geometry (e.g. sweep, prebending, or deflection under load) or from the anisotropic properties of the blade material. Bend-twist coupling can be utilized to reduce the fatigue loads of wind turbine blades. In this study the effects of material-based coupling on the aeroelastic modal properties and stability limits of the DTU 10 MW Reference Wind Turbine are investigated. The modal properties are determined by means of eigenvalue analysis around a steady-state equilibrium using the aero-servo-elastic tool HAWCStab2 which has been extended by a beam element that allows for fully coupled cross-sectional properties. Bend-twist coupling is introduced in the cross-sectional stiffness matrix by means of coupling coefficients that introduce twist for flapwise (flap-twist coupling) or edgewise (edge-twist coupling) bending. Edge-twist coupling can increase or decrease the damping of the edgewise mode relative to the reference blade, depending on the operational condition of the turbine. Edge-twist to feather coupling for edgewise deflection towards the leading edge reduces the inflow speed at which the blade becomes unstable. Flap-twist to feather coupling for flapwise deflections towards the suction side increase the frequency and reduce damping of the flapwise mode. Flap-twist to stall reduces frequency and increases damping. The reduction of blade root flapwise and tower bottom fore-aft moments due to variations in mean wind speed of a flap-twist to feather blade are confirmed by frequency response functions.

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Section: Discussionmentioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Section: A R Stäblein Et Al: Modal Properties and Stability Of Benmentioning

confidence: 99%

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Modal properties and stability of bend–twist coupled wind turbine blades

2017

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Section: Introductionmentioning

confidence: 99%

“…The aeroelastic modal properties and stability limits of both edge-and flap-twist coupled blades are investigated by means of eigenvalue analysis around a steady-state equilibrium using the aero-servoelastic tool HAWCStab2. For the analysis with fully coupled cross-section stiffness matrices the beam element of Kim et al (2013) has been implemented in HAWCStab2.…”

Section: Introductionmentioning

confidence: 99%

Modal Properties and Stability of Bend-Twist Coupled Wind Turbine Blades

Stäblein¹,

Hansen²,

Verelst³

2016

Preprint

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Coupling between bending and twist has a significant influence on the aeroelastic response of wind turbine blades. The coupling can arise from the blade geometry (e.g. sweep, prebending, or deflection under load) or from the anisotropic properties of the blade material. Bend-twist coupling can be utilized to reduce the fatigue loads of wind turbine blades. In this study the effects of material-based coupling on the aeroelastic modal properties and stability limits of the DTU 10 MW Reference Wind Turbine are investigated. The modal properties are determined by means of eigenvalue analysis around a steady-state equilibrium using the aero-servo-elastic tool HAWCStab2 which has been extended by a beam element that allows for fully coupled cross-sectional properties. Bend-twist coupling is introduced in the cross-sectional stiffness matrix by means of coupling coefficients that introduce twist for flapwise (flap-twist coupling) or edgewise (edge-twist coupling) bending. Edge-twist coupling can increase or decrease the damping of the edgewise mode relative to the reference blade, depending on the operational condition of the turbine. Edge-twist to feather coupling for edgewise deflection towards the leading edge reduces the inflow speed at which the blade becomes unstable. Flap-twist to feather coupling for flapwise deflections towards the suction side increase the frequency and reduce damping of the flapwise mode. Flap-twist to stall reduces frequency and increases damping. The reduction of blade root flapwise and tower bottom fore-aft moments due to variations in mean wind speed of a flap-twist to feather blade are confirmed by frequency response functions.Published by Copernicus Publications on behalf of the European Academy of Wind Energy e.V.

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Effects of bend-twist coupling on flutter limits of composite wind turbine blades

Zhou

Huang

2018

Composite Structures

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Some Effect of Large Blade Deflections on Aeroelastic Stability

Cited by 12 publications

References 3 publications

Modal properties and stability of bend–twist coupled wind turbine blades

Modal properties and stability of bend–twist coupled wind turbine blades

Modal Properties and Stability of Bend-Twist Coupled Wind Turbine Blades

Effects of bend-twist coupling on flutter limits of composite wind turbine blades

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