A novel analytical wake model for floating offshore wind turbines with pitch motion effects

With the growing scale of offshore wind farms, the resulting intensification of wake effects between floating offshore wind turbines (FOWTs) adversely affects the overall power generation efficiency. Traditional wake models demonstrate limitations in predicting the complex wakes generated by FOWTs experiencing motions in marine conditions, particularly the pitch motion induced by waves. This paper presents a novel three-dimensional anisotropic analytical wake model, which incorporates the influence of periodic pitch motion and wind shear. Additionally, the model employs a Gaussian distribution to characterize the wake in the near-wake region (pressure-dominated), resolving the limitations of traditional three-dimensional wake models that rely on top-hat distributions in this region. The detailed derivation process is demonstrated in the paper. The model is validated against published wind tunnel measurement and high-fidelity CFD data, demonstrating its accuracy and applicability. Finally, the impact of varying pitch amplitudes on the wake velocity distribution is analyzed. The results show that at the downwind position of X/D = 5, which is a typical interval among wind turbines, the normalized velocities at pitch angles of 2°, 5°, 8°, and 10° are 1.015, 1.036, 1.055, and 1.069 times that of 0°, respectively. The proposed wake model can effectively evaluate the wake distribution of FOWTs with different pitch amplitudes. This study can provide a reference for the wake modeling of FOWTs.