Prediction and Alleviation of Flutter in Swept Wind Turbine Blades

Document Type

Conference Presentation

Department

Mechanical Engineering

Conference Title

33rd Wind Energy Symposium

Organization

American Institute of Aeronautics and Astronautics (AIAA) SciTech

Location

Kissimmee, FL

Conference Dates

January 5-9, 2015

Date of Presentation

1-7-2015

Abstract

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.

DOI

10.2514/6.2015-1464

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