Hybrid aeroelastic models on dynamic responses of wind turbine blades

Accurate and robust aeroelastic modelling is playing an important role in the design of large wind turbines nowadays, due to the dramatical size increasing of the blades which require extra attentions to be paid to flexibility and deformation analysis. Linear Beam Theory (LBT) and Geometrically Exact Beam Theory (GEBT) are introduced in this paper, and coupled with classic Blade Element Momentum Theory (BEMT) to predict the aerodynamic performance and the dynamic responses of wind turbine blades of different sizes. BEMT-LBT model has higher computational efficiency as a linear aeroelastic model while BEMT-GEBT model considers the nonlinear deformation of the blades as a nonlinear model. The results show that the impacts of the linear and nonlinear models on the dynamic responses is more significant on larger blades, and the difference of the flapwise deformation of the blade tip reaches 18.14% at 10MW size. There is no significant difference between dynamic responses of the blades of a 1.5MW wind turbine or less, calculated by two aeroelastic models. For the ultra-long blades of the 5MW and 10MW wind turbines, the BEMT-LBT linear aeroelastic model overestimates their deformations due to the assumption of small blade deflections.