Using Pretwist to Reduce Power Loss of Bend-Twist Coupled Blades

Alexander Stäblein, Carlo Tibaldi, Morten Hartvig Hansen

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    Bend-twist coupling of wind turbine blades is known as a means to reduce the structural loads of the turbine. While the load reduction is desirable, bend-twist coupling also leads to a decrease in the annual energy production of the turbine. The reduction is mainly related to a no longer optimal twist distribution along the blade due to the coupling induced twist. Some of the power loss can be compensated by pretwisting the blade. This paper presents a pretwisting procedure for large blade deflections and investigates the effect of pretwisting on blade geometry, annual energy production, and fatigue load for the DTU 10 MW Reference Wind Turbine. The analysis was carried out by calculating the nonlinear steady state rotor deflection in an uniform inflow over the operational range of the turbine. The steady state power curve together with a Rayleigh wind speed distribution has been used to estimate the annual energy production. The turbine model was then linearised around the steady state and the power spectral density of the blade response, which was computed from transfer functions and the wind speed variations in the frequency domain, was used to estimate the fatigue loads by a spectral method.
    Original languageEnglish
    Title of host publicationProceedings of the 34th Wind Energy Symposium
    Number of pages14
    PublisherAmerican Institute of Aeronautics and Astronautics
    Publication date2016
    Article numberAIAA 2016-1010
    Publication statusPublished - 2016
    Event34th Wind Energy Symposium - San Diego, CA, United States
    Duration: 4 Jan 20168 Jan 2016
    Conference number: 34


    Conference34th Wind Energy Symposium
    Country/TerritoryUnited States
    CitySan Diego, CA
    Internet address


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