Prediction and Alleviation of Flutter in Swept Wind Turbine Blades
33rd Wind Energy Symposium
American Institute of Aeronautics and Astronautics (AIAA) SciTech
January 5-9, 2015
Date of Presentation
Previous research has shown that as wind turbine rotor designs increase in diameter they approach flutter instabilities. Recent blade designs incorporate blade sweep to lower fatigue loads and increase rotor diameter for more energy production; however, the flutter margin may be reduced with sweep. In this work, the author predicted and compared the flutter speed for turbines with straight and swept blades. For the study, the author used a wind turbine analysis tool specifically developed for blade sweep (CurveFAST), in addition to a tool developed for helicopter analysis (RCAS). The results showed that CurveFAST generally preceded a higher flutter speed and RCAS predicted a lower flutter speed compared to previous research. The difference may be attributed to the unsteady aerodynamics modeling. Results for an extended radius and swept 5 MW turbine showed the flutter speed was most sensitive to the position of the blade center of mass axis. Using the selected design parameters, it was not possible to design a swept-5 MW blade with adequate flutter margin that would produce 5% more energy with the same loads as a baseline straight rotor.
Larwood, S. M.
Prediction and Alleviation of Flutter in Swept Wind Turbine Blades.
Paper presented at 33rd Wind Energy Symposium in Kissimmee, FL.