Wake morphology and recovery mechanisms in floating wind farms

Floating offshore wind has the potential to unlock the vast wind energy resources over deep waters. However, achieving the potential of this technology requires a deeper understanding of how the dynamics introduced by coupling between the wind, wakes, and turbine platform affect wake interactions and farm level power output. This presentation will describe floating offshore wind farm experiments performed in the Portland State wind and wave tunnel to explore these dynamics under various wave conditions.

The farm is constructed of a four-by-three layout spaced at 5D in x and 3D in z, with 15 cm diameter turbines. The farm’s flow field is measured using 2D-3C particle image velocimetry. Individual turbine motion is captured using optical tracking, and power output is measured through generators placed in the nacelle of each turbine.

Flow field results are described in terms of both ensemble and wave-phase-averaged quantities. Phase averaging is shown to reveal different wave-dependent behavior and structures that are not evident in the ensemble sense. Wake center and width identification are performed and used to reveal wake stretching and deflection induced by different wave phases.