From the Penn State Cyber Wind Facility (CWF) program we present a computer-generated animation of a commercial wind turbine rotor operating in the daytime atmospheric boundary layer (ABL)—focusing on the nonsteady dynamic response of wind turbine blade and rotor loadings to the passage of the 3D coherent turbulent atmospheric eddies. Although correlated horizontal-vertical velocity fluctuations pass through the rotor disk at the minute time scale, as the blades rotate through the eddies at the 5 s time scale blade loads respond at sub-revolution time scales, causing large < 1 s fluctuations in blade loads, torque and power. We show the blade/rotor responses at different time scales by combining iso-surface/contour visualization with quantitative measures from large-eddy simulation (LES) of the NREL 5 MW wind turbine operating in a typical daytime ABL using the actuator line blade model. The animation shows how the nonsteady loadings generate nonsteady bending moments on the low-speed shaft that underlie bearing failures and increased cost of energy. We also show blade-generated turbulent vortices that create smaller-scale wake turbulence and nonsteady loadings on downstream wind turbines. Supported by DOE/EERE, Penn State College of Engineering, NSF XSEDE.
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