Prediction of wind turbine blade aeroelastic instability under trailing edge windward states using blade element damping method

With the increase in blade size and decrease in structural stiffness of wind turbines, aeroelastic stability and vibration have become a key technical challenge in blade design. Particularly, there is a significant lack of fast and accurate prediction techniques for trailing-edge-windward flapwise aeroelastic instability, posing a major obstacle to industry growth. To address this issue, this study develops a fast aeroelastic stability prediction method for 3D blades under trailing-edge windward conditions. The method is developed based on blade element theory, dividing the blade into multiple reference blade elements, with each element treated as an independent two-dimensional airfoil. The aeroelastic damping characteristics of each reference airfoil is then computed using the reduced-order model (ROM) approach. Subsequently, by integrating the blade structural modal information and the modal damping coefficient corresponding to the reference airfoils, the modal superposition method is employed to derive the aeroelastic damping of the entire blade. Using this constructed blade-element reduced-order model (BE-ROM) damping method, it successfully predicted the aeroelastic instability region of a large-scale blade for incidence angles ranging from 177° to 183°, with validation provided by wind tunnel tests. Furthermore, the potential destabilization trigger is revealed by investigating the influence of geometric parameters on the aeroelastic behaviors. The upper section of the blade exerts the most prominent effect on the blade overall destabilization.