Effects of large bending deflections on blade flutter limits

Bjarne Skovmose Kallesøe, Morten Hartvig Hansen

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    Abstract

    The coupling of bending and torsion due to large blade bending are assumed to have some effects of the flutter limits of wind turbines [1]. In the present report, the aeroelastic blade model suggested by Kallesøe [2], which is similar to the second order model used in [3], is used to investigatethe aeroelastic stability limits of the RWT blade with and without the effects of the large blade deflection. The investigation shows no significant change of the flutter limit on the rotor speed due to the blade deflection,whereas the first edgewise bending mode becomes negatively damped due to the coupling with blade torsion which causes a change of the effective direction of blade vibration. These observations are confirmed by nonlinear aeroelastic simulations using HAWC2 [4, 5].
    This work is part of the UpWind project funded by the European Commission under the contract number SES6-CT-2005-019945 which is gratefully acknowledged. This report is the deliverable D2.3 of the UpWind project
    Original languageEnglish
    Place of PublicationRoskilde
    PublisherDanmarks Tekniske Universitet, Risø Nationallaboratoriet for Bæredygtig Energi
    Number of pages12
    ISBN (Print)978-87-550-3665-9
    Publication statusPublished - 2008
    SeriesDenmark. Forskningscenter Risoe. Risoe-R
    Number1642(EN)
    ISSN0106-2840

    Keywords

    • Risø-R-1642
    • Risø-R-1642(EN)

    Cite this

    Kallesøe, B. S., & Hansen, M. H. (2008). Effects of large bending deflections on blade flutter limits. Danmarks Tekniske Universitet, Risø Nationallaboratoriet for Bæredygtig Energi. Denmark. Forskningscenter Risoe. Risoe-R, No. 1642(EN)