Study Of Fluid Structure Interaction Response Of Wind Turbine In Typhoon Environments And Wind Resistance Of Adaptive Blade

With the increasing of coastal wind power and offshore wind power in China,the frequent typhoon on the southeast coast of China have become one of the key factors restricting the development of wind power.Modern wind turbine design standards are mostly developed from the EU region without typhoon,which may make it difficult for wind turbines designed to adapt to the multi-typhoon coastal environment in China.It can be seen that there are still many unknown factors in the failure mechanism of typhoon-induced structural damage of wind turbines to be explored.Therefore,for the drawbacks of the traditional studies and the unilateral fluid or structural numerical simulation,this paper uses the fluid-structure interaction numerical simulation method to study the flow field characteristics and structural response of large horizontal axis wind turbines in typhoon environment,so sa to explore the failure mechanism of the wind turbine structure.In addition,based on the failure characteristics of wind turbine structure,this paper proposes using the passive adaptive characteristics of bend-twist coupling blades to resist the typhoon.The specific research content of the thesis are shown as followed:1.Based on the parametric modeling method,the parameterized three-dimensional high-precision MW-class wind turbine model is established through secondary development,and the synchronous reconstruction mechanism is established by coupling with CFD and FEM programs,and CAD-CFD grid parameter construction is developed.The parametric model and CAD-FEM composite pavement design makes the wind turbine numerical model conform to the real processing characteristics while simplifying the complex modeling,thus ensuring the accuracy of the fluid-structure interaction numerical simulation of the wind turbine under typhoon environment.2.Based on the fluid-structure interaction method combining CFD and FEM,the aerodynamic characteristics and structural response characteristics of the 5.0 MW wind turbines in extreme typhoon environment are analyzed to explore the external environmental incentives and internal structural failure caused by typhoon.Firstly,according to the CFD method and the time/frequency domain analysis method,the influence of typhoon wind direction and wind turbine stop phase angle on wind turbine aerodynamic load is explored.The result indicates that the specific rotor position can cause abnormal aerodynamic load,resulting in high failure risk for the wind turbine.Secondly,for the high failure risk state of the maximum load,the structural strength and stability of the wind turbine are studied by the two-way FSI quasi-static analysis method,and the stress distribution state of the interlayer of the composite laminate is analyzed in depth.It indicates that the variation of structure properties is the main cause of the fracture or the local buckling instability for the blade and tower.For the high failure risk state of the vortex-induced vibration of the blade,the vortex shedding frequency and the corresponding aerodynamic load oscillation of the typhoon wind shear and turbulent typhoon on the blade flow field are studied.In addition,the FEM analysis and harmonic response analysis are used to study the intrinsic factors of composite blade structure failure caused by vortex-induced vibration of the flow field.The results show that the blade in the drooping position may be broken even in a low speed typhoon environment that is much lower the limited speed.Finally,the two-way FSI dynamic response method is used to study the dynamic response of wind turbine blades under various high-risk conditions,and the nonlinear failure phenomenon caused by large-scale deformation and a multi-axial load of the blade in typhoon environment is analyzed.Local dynamic nonlinear buckling failures that are difficult to consider in wind turbine design methods may also cause damage to the blades under low wind speed typhoons.3.Based on the failure mechanism of wind turbine blade which is vulnerable to structural damage caused by overload and vortex excitation in typhoon environment,this paper proposes using the adaptive blade to resist the abnormal load state caused by typhoon environment.Firstly,different kinds of bend-twist coupling blade geometry models,CFD model and FEM models are created by parametric modeling.Secondly,for the conditions of the maximum load,the FSI method is used to analyze the load mitigation performance of different bend-twist coupling blades.The results show that the ?=15° fiber deflection swept blade can significantly reduce the blade ultimate load,and its FEM analysis shows that this blade reduces the surface maximum stress by 22.3%.Finally,for the vortex-induced vibration conditions,the aerodynamic performance of each blade is studied by FSI method in time/frequency domain analysis.The results show that the swept blades with ?=15° fiber deflection can reduce the amplitude and frequency of vortex-induced vibration.Effectively reduce structural damage caused by vortex induced vibration.