NSF Grant No. CMMI2034111, NSF Grants No. NSF-CMMI-2034160, No.NSF-CBET-2227263, and No. NSF-CBET-2037582
Physical Review Fluids
In this study, wind and water tunnel experiments of turbulent wakes in a scaled floating wind farm are performed. Scaling of a floating wind farm with a scaling ratio of 1:400 is made possible by relaxing geometric scaling of the turbine platform system, such that the dynamic response can be correctly matched, and to allow for relaxing Froude scaling such that the Reynolds number can be kept large enough. Four dimensionless parameters, describing the relative importance of wind and wave loads compared to turbine inertia, are used to guide the scaled floater design. Free decay tests of the pitch and heave response confirm that the dimensionless natural frequency of the scaled model is in the typical range for full-scale floating turbines when matching the proposed four dimensionless parameters. The response and performance of a single turbine scaled model are characterized for different wind and wave conditions. Subsequently, a wind farm experiment is performed with twelve floating turbine models, organized in four rows and three columns. Particle image velocimetry measurements of the wake of the middle turbine in the third row reveal distinct differences in wake properties for different wave conditions. Conditional averaging confirms a synchronization of wake deflection with the traveling waves in the wind farm. The power outputs show distinct peaks at the wave frequencies and its harmonics, due to motions triggered by complex wave-turbine-wake interactions. The power spectrum of the aggregate power of three streamwise aligned turbines exhibits anticorrelation of motions at The power spectrum of the aggregate power of three streamwise aligned turbines exhibits anticorrelation of motions at the wave frequency due to wave speed induced phase lag, and spatiotemporal correlations of power outputs at the frequency corresponding to the wind-convective time between two rows. These experiments using an appropriately scaled floating wind farm in a wind tunnel setup confirm distinct impacts of turbine motion on wake recovery and meandering, and measurement results highlight the intricate interactions between wave topology and wake meandering.
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Bossuyt, J., Ferčák, O., Sadek, Z., Meneveau, C., Gayme, D. F., & Cal, R. B. (2023). Floating wind farm experiments through scaling for wake characterization, power extraction, and turbine dynamics. Physical Review Fluids, 8(12), 120501.