Numerical Model of Structural Dynamic Response for Wind Turbine Flexible Blade

Due to the instability of the incoming wind speed and the nonlinear large deformation of large horizontal axis wind turbine flexible blade, a numerical model was established to quickly calculate the unsteady load, modal characteristic parameters and structural dynamic response. Firstly, a time-varying equivalent load model of rotor was established using the dynamic inflow theory, which integrated added mass force, aerodynamic force, centrifugal force and gravity. Then, the blade was discretized into a hybrid beam element considering the blade spanwise displacement and lateral shear deformation by using the weighted residual method and Galerkin method. The modal parameters were solved by subspace iteration method. Finally, the dynamic response equation under time-varying load was decoupled by the Houbolt method. The research results showed that the tip flapwise displacement increased sharply first and then decreased with the increase of wind speed, and the amplitude fluctuation always followed the direction of incoming flow. However, the blade tip edgewise displacement presented an opposite change trend and fluctuated periodically with the positive and negative deformation. The centrifugal stiffening effect has a great influence on the natural frequency of the flapwise direction, while the influence of the edgewise direction was relatively weak. The influence degree decreased with the increase of modal order. Some calculation results in this paper were compared with the NREL, Shantou University and software GH Blade, which proved that the model was accurate. © 2022, Science Press. All right reserved.