Dynamics of Wind, Waves, and Wakes in a Floating Offshore Wind Farm

Floating turbines are subject to hydrodynamic forcing by passing ocean waves, introducing the turbine to six degrees of freedom; leading to potential controls opportunities which can be leveraged to optimize power generation across an array. We analyze experimental data being obtained at the Portland State University (PSU) Wind Energy and Turbulence (WET) lab. Data are generated in a closed-circuit wind tunnel, complemented by a wave tank and particle image velocimetry (PIV) system. A 3x4 model turbine array floating offshore wind plant, installed in the wave tank with spanwise and streamwise spacings of two and six rotor diameters, respectively, will be used for the measurements. A series of vertical-transverse PIV planes will be taken of a single inner-array turbine at increasing downstream locations. An adaptive wave generator, active grid, and series of wind tunnel speeds will be used to generate a variety of waveforms and inflow conditions used to characterize the response of the plant. Results will be used to calculate time-averaged turbulence statistics and quantify the effects of hydrodynamic forcing through phase-averaging of wave position. The results can help provide a fundamental understanding of how coupled wind, wave, and wake dynamics influence floating offshore wind plant performance. Data will be used for comparisons with concurrent LES studies that use a novel surface gradient wall model that accounts for moving bottom surfaces by modifying the surface stress in a time-varying fashion.