Date

2017-09-22

Author

Atalay, Oğuz
Farsadi, Touraj
Kayran, Altan

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Use of bend-twist coupled blades is one of the ways to alleviate fatigue loads in wind turbine systems. Load reduction is achieved by placing off-axis layers in the spar caps of composite wind turbine blades. Off-axis layers provide twisting of the blade in the feathering direction thereby decreasing the aerodynamic loads due to the reduced effective angle of attack. Reduction of fatigue loads in the wind turbine system is generally measured by the damage equivalent load. In the present study, performance of bend-twist coupled blades designed for a 5 MW wind turbine is investigated for the wind speeds ranging from the cut-in speed to the overrated wind speeds. The initial analysis of the wind turbine is done at the overrated speed of 15 m/s and it is shown that reduction in damage equivalent loads is achieved at almost no loss in the rated power compared to the reference wind turbine with the baseline blade. However, it is also demonstrated that at the underrated speeds; although reduction in damage equivalent loads can still be achieved with the bend-twist coupled blade, power loss occurs compared to the reference turbine. This study aims to make a performance study of wind turbine systems with bend-twist coupled blades in terms of load reduction achieved and power production and to propose modifications to simultaneously reduce the generator power losses and damage equivalent loads. As a preliminary design modification, it is shown that by reducing the pre-twist angle of the bend-twist coupled sections of the blades, it has been possible to eliminate the power loss disadvantage of wind turbines at the underrated wind speeds, while still achieving reduction in damage equivalent loads.

URI

https://hdl.handle.net/11511/76518

Collections

Department of Aerospace Engineering, Conference / Seminar