Design of an aeroelastically tailored wind turbine blade tip for field experiments
report
This report explores the impact of a swept wind turbine blade tip on extreme and fatigue blade and tower loading through numerical investigations. These are conducted within the context of the TIADE project, a field experiment on a 3.8 MW research turbine, which planned a campaign with segmented blades that allow the application of alternative tip geometries. Within the available tip design space, dictated by the position and allowable load of a blade tip joint, the maximum allowable tip sweep is determined. Based on aeroelastic simulations of design load cases 1.2 and 1.3 according to IEC standard
61400-1, the sweep-induced changes to fatigue and extreme loads at blade root, tip joint and tower bottom are evaluated. It is demonstrated that a reduction in flapwise blade root extreme loads and lifetime damage-equivalent loads of 1.0 % and 2.6 %, respectively, can be achieved when compared against a straight reference blade. At the tip joint, the relative flapwise load reductions are even larger. Torsional loads are shown to also decrease at the blade root but increase in the swept part of the blade where the coupling of bending and torsional deformations due to sweep is strongest. Edgewise loads are largely insensitive to sweeping the blade tip. Tower bottom loads also decrease, with fore-aft extreme and damage equivalent fatigue loads exhibiting the most pronounced relative reductions of 1.6 % and 2.1 %, respectively. Finally, the rotor performance is shown to hardly be affected by blade sweep.
61400-1, the sweep-induced changes to fatigue and extreme loads at blade root, tip joint and tower bottom are evaluated. It is demonstrated that a reduction in flapwise blade root extreme loads and lifetime damage-equivalent loads of 1.0 % and 2.6 %, respectively, can be achieved when compared against a straight reference blade. At the tip joint, the relative flapwise load reductions are even larger. Torsional loads are shown to also decrease at the blade root but increase in the swept part of the blade where the coupling of bending and torsional deformations due to sweep is strongest. Edgewise loads are largely insensitive to sweeping the blade tip. Tower bottom loads also decrease, with fore-aft extreme and damage equivalent fatigue loads exhibiting the most pronounced relative reductions of 1.6 % and 2.1 %, respectively. Finally, the rotor performance is shown to hardly be affected by blade sweep.
Topics
TNO Identifier
1005527
Publisher
TNO
Collation
26 p.
Place of publication
Petten