An Analytical Model of Floating Offshore Wind Turbine Blades Considering Bending-Torsion Coupling Effect

Abstract

In this paper, an analytical model is proposed to describe the nonlinear vibration of blades on floating offshore wind turbine (FOWT). The bending-torsion coupling equations are derived based on Hamilton’s principle. Comparing with the classical Newtonian method, this approach is more mathematically rigorous and systematic. The flapwise and edgewise deformation, the torsion as well as axial extension of the blades are all included in the model. A set of partial differential equations governing the coupled nonlinear vibration is established, and the results are compared with the multi-body model. Some details about the solution of equations are discussed. The eigen values of a rotating blade is also calculated. The structural model proposed in this paper can be widely used in the future study. For example, it can be coupled with an aerodynamic model to study the aeroelastic properties of the wind turbine blades. The effect of platform motion on blade dynamic response can also be obtained based on this analytical model.