LES simulation study of wind turbine aerodynamic characteristics with fluid-structure interaction analysis considering blade and tower flexibility

As wind turbine blades become longer and more flexible, aerodynamic characteristics become increasingly complex and require complete investigations. In this study, a two-way fluid-structure interaction (FSI) model is proposed to analyze the effects of inflow conditions, including uniform and atmospheric boundary layer (ABL) winds, as well as blade and tower flexibility, on the aerodynamic characteristics of wind turbine blades. A 4.5 MW real wind turbine with the rotor diameter of 152 m and the hub height of 94 m is considered. Results show that the edgewise blade motion can be disregarded, while the motion of the tower and the flap-wise motion of blade significantly influence the aerodynamic characteristics of blades. The separation flow at the blade root suction side is more distinct and becomes less significant with an increase in spanwise distance, with stagnation points primarily distributed along the flow separation boundary at 0.45–0.95L (L is the blade length). The three-dimensional rotational effect of the blade induces notable fluctuations in the pulsating pressure coefficient, particularly within this region. Notably, a prominent peak is observed at the location of 0.65L. Consequently, it is recommended to allocate additional focus on this specific region to mitigate potential fatigue loads.