Analysis Of Dynamic Characteristics And Response For Rotating Blades Of Wind Turbine

Aimed at the configuration and operation characteristics of the modern large-scale horizontal axis wind turbine, using the modern flexible multi-body dynamics theory combined with finite element numerical analysis method, The dynamic characteristics and structural dynamic response caused by the aerodynamic and mechanical loads of the large-scale wind turbine blade was investigated. The main investigation include: The establishment of the general flexible multi-body dynamics finite element equations of the large scale wind turbine rotating blade and the study of its numerical solving methods; The vibration characteristic analysis of the blade; The dynamic response analysis of the rotating blade when the aerodynamic and mechanical loads are applied on the blade.Above all, the modern flexible multi-body dynamics theory and the finite element method are briefly introduced and the model building of the blade is carried out using the FEM analysissoftware——ANASY, by which the natural frequencies and the modalities of a 1.5MW variablespeed pitch regulated wind turbine GRP blade are calculated. The stiffening reasons of the rotating blade and the influence of the dynamic stiffening effect on the blade natural frequencies are discussed.And then, Using Kane's dynamics equations and taking finite element discretization about the rotating blade, the general flexible multi-body dynamics finite element equations of the large scale wind turbine rotating blade are developed. The apparent three dimensional beam element dynamical matrices are obtained according to the characteristic geometry shape of the rotating blade based on the Timoshenko model. The natural frequencies and modalities of the 1.5MW turbine blade are obtained by general FEM and flexible multi-body dynamics method respectively and the results are compared with the aforementioned results obtained through ANSYS.Finally, the dynamic response analysis is gone on according to the established blade dynamic model. For these kinds of time-variant dynamic equations, the integral numerical method is introduced to solve the dynamical equations and the stability of results and efficiency of arithmetic of three numerical methods ( newmark - β , wilson - θ , newmark increment iteration) are analyzed and the corresponding FEM program is developed to carry through the numerical analysis. The bending flexibility response in startup, brake and normal operation state of a 1.5MW wind turbine blade are figured out and compared with those calculated by conventional finite element analysis method. The results show that this flexible multi-body dynamics method can more accurately express the dynamic characteristics and dynamic response of a rotating blade.