Shape memory alloy‐based centrifugal stiffening for response reduction of horizontal axis wind turbine blade

Abstract

The aim of this study is to reduce the deformation of large horizontal axis wind turbine blades using shape memory alloy (SMA)-based centrifugal stiffening. A discrete model considering dominant modes of the tower, drive train and blades is developed in this study to demonstrate the performance of the proposed stiffening strategy. Here, super-elastic behaviour of SMA is characterized by Graesser-Cozzarelli model. Aerodynamic loads acting on the blades are evaluated using blade element momentum theory. The response is simulated using aerodynamic damping, which is estimated in each mode of vibration. Numerical results presented in this paper clearly show the significance of the proposed SMA-based stiffening to reduce blade vibration. Sensitivity analysis is also carried out to demonstrate the performance envelop of the proposed stiffening strategy over the operational range of the benchmark 5-MW wind turbine. The study clearly highlights the performance enhancement in terms of deformation in two orthogonal directions and design in terms of longitudinal stress that ultimately improve the serviceability of the blade.