Date of download: 6/26/2016 Copyright © ASME. All rights reserved. Flutter of Variations on a 5 MW Swept Wind Turbine Blade 1 J. Sol. Energy Eng. 2016;138(2): doi: / Rotor speed reduction after the onset of flutter in an 8 kW wind turbine [1] Figure Legend:

Date of download: 6/26/2016 Copyright © ASME. All rights reserved. Flutter of Variations on a 5 MW Swept Wind Turbine Blade 1 J. Sol. Energy Eng. 2016;138(2): doi: / CurveFAST results for flutter instability of a 1.5 MW wind turbine in still air. Negative twist is toward feather. Nominal speed is 20.5 rpm. Figure Legend:

Date of download: 6/26/2016 Copyright © ASME. All rights reserved. Flutter of Variations on a 5 MW Swept Wind Turbine Blade 1 J. Sol. Energy Eng. 2016;138(2): doi: / Plots of frequency and damping for the Sweep5000 baseline model with frequency normalized to omega = 1.27 rad/s (12.1 rpm rated speed). Modes 1—first flapwise, 2—first edgewise, 3—second flapwise, and 4—second flap/torsion. (a) Frequency, fan lines are integer multiples of rotor speed and (b) damping, which goes positive for mode 4, indicating an instability. Figure Legend:

Date of download: 6/26/2016 Copyright © ASME. All rights reserved. Flutter of Variations on a 5 MW Swept Wind Turbine Blade 1 J. Sol. Energy Eng. 2016;138(2): doi: / Animation screen capture of unstable aeroelastic mode 4 for the Sweep5000 baseline model. Left portion of tip is the undeflected blade; right portion shows the deflection. The animation shows motion that is a combination of the second flap mode and the first torsion mode. Figure Legend:

Date of download: 6/26/2016 Copyright © ASME. All rights reserved. Flutter of Variations on a 5 MW Swept Wind Turbine Blade 1 J. Sol. Energy Eng. 2016;138(2): doi: / Swept blade parameters. Torsional stiffness is about the elastic axis. Figure Legend:

Date of download: 6/26/2016 Copyright © ASME. All rights reserved. Flutter of Variations on a 5 MW Swept Wind Turbine Blade 1 J. Sol. Energy Eng. 2016;138(2): doi: / Parametric study of the baseline Sweep5000 wind turbine with RCAS. Torsion is change in torsional stiffness at every blade station. Tip sweep is percentage of maximum chord length. Exponent is the change from the baseline exponent of 2. CM is percentage of chord from elastic axis to mass center axis; positive toward trailing edge. Figure Legend: