Temporal wake analysis under coupled operating conditions based on time-varying wake model of floating wind turbine under multi-source forces

The wake of the floating wind turbines exhibits complex evolutionary characteristics under dynamic fluctuations caused by coupled boundary conditions at sea. The study proposed a novel time-varying wake model to analyze the dynamic distribution patterns of wake velocities. The model comprehensively accounted for the influence of multi-source forces-including wind, waves and mooring-on the inflow velocities actually acting on floating wind turbines. Based on potential flow theory, the response characteristics of six-degree-of-freedom parameters were quantified, and the steady-state characterization of the original static model was revised through the solution of time-domain equations of motion. The accuracy of the proposed dynamic wake model was further validated by combining data from various operating conditions reported in the literature with existing mathematical representations of wake. Finally, the differences in the temporal decay characteristics of wake across different wind-wave coupling scenarios were analyzed. The results indicate that the relative error of the proposed model can be controlled within 6%, making it more suitable for characterizing the dynamic properties of wake velocities compared to the Frandsen model and the 3D-OFWT model. The reverse speed of the turbine promotes velocity recovery in the wake region, whilst higher turbulence intensity also has a positive effect on reducing wake deficit. Under extreme condition, wake deficit occurs more rapidly than under steady or normal conditions. However, the turbine is subjected to significant rotor thrust and mooring forces. The study provides the reference for the decomposition of wake fields and layout optimization for offshore floating wind turbines.