Numerical investigation on wake characteristics of floating offshore wind turbine under pitch motion

The floating offshore wind turbine platform is subject to six degrees-of-freedom motions due to the influence of wind, waves, and currents. To examine the impact of pitch motion on the wake characteristics of offshore wind turbines, this research focused on investigating the wind turbine wake under pitch motion using the RANSk-& epsilon;$k - \varepsilon $ model and the overset grid technique based on OpenFOAM. The simulation accounted for wind shear flow conditions and simplified the movements of the six degrees-of-freedom of floating platform. Results showed that the wind turbine wake recovery rate increased with pitch motion, and that the recovery rate increased with the frequency and amplitude of the pitch motion. The wind velocity recovery rate of near-wake was sensitive to small amplitudes, while the far-field wake was unaffected. When the amplitude was larger, pitch motion accelerated the wind velocity recovery rate in all wake areas, leading to more pronounced diffusion. These findings provide insight into the mechanism of wake generation and diffusion under pitch motion in floating offshore wind turbines and offer a basis for enhancing the wake deficit model of floating offshore wind farms.