| With the continuous depletion of traditional energy sources and the increasing environmental pollution problems in the world,wind energy as a renewable and clean energy has become the direction for humans to explore new energy sources.Nowadays,large-scale and high-efficiency wind turbines have become the mainstream trend in the development of wind power industry.The larger the diameter of the wind turbine,the more factors affecting the stability of the wind turbine.The wind shearing effect is caused by the ground friction,which causes the wind speed to be unevenly distributed in the vertical direction,so the aerodynamic force of the blade in the direction of the blade is different,which results in uneven distribution of the blade's spanning load and has a great influence on the blade structure.In order to research the influence of wind shear on the aerodynamic performance and structural performance of large wind turbine blades,this thesis takes NREL 5MW wind turbine published by American Renewable Energy as the research object,and uses numerical simulation method to research.The main contents are as follows:Firstly,the influence of wind shear effect on the aerodynamic performance of wind turbine blades is researched.The 5MW wind turbine blades were modeled for aerodynamic shape and internal and external flow fields using SolidWorks software.By loading the UDF function to give the shear flow velocity,the k-? SST turbulence model is used to simulate the wind turbine model with different flow velocity and different wind shear index.The results show that the shear flow condition is lower.The axial thrust and power of the wheel are significantly lower than the axial thrust and power of the wind wheel when the flow is uniform.As the wind shear index increases,the axial thrust and power of the wind wheel will become closer and closer to the uniform flow.The axial thrust and power of the wind wheel;the axial load and the circumferential load of different sections in the direction of the blade show periodic variation with the azimuth angle,the maximum value is reached when the azimuth angle is 0,and the minimum value is reached when the azimuth angle is 180.With the increase of wind shear index,the load at the root of the leaves showed obvious h ysteresis.Secondly,the influence of wind shear effect on the structural performance of wind turbine blades is studied.The ANSYS mechanical APDL software is used to complete the finite element model of the blade.The main beam,web,leading edge and trailing edge of the wind turbine blade are divided,the unit type and material type of the blade are defined,and different layer definitions at different components are completed..The layup angle,smoothness and layup ratio of the laminate at the main beam of the blade are improved.The calculation results show that the pavement of ±45° is added to the main beam of the blade and the proportion of the pavement with ±45° is 30.From % to 40%,the structural properties of the blade are improved from both strength and mode.Finally,the transient analysis and fatigue analysis module of ANSYS is used to estimate the fatigue life of wind turbine blades.The calculation results show that under the influence of shear flow,the displacement at different nodes of the blade will change periodically with time.The displacement of the node at the trailing edge of the blade is the largest,the displacement of the node at the leading edge is the smallest,and the variation of the displacement of the node at the main beam of the blade is between the two,so it is accompanied by the torsional deformation of the blade.As the wind shear index increases,the blade life will also decrease accordingly.In this thesis,the effects of wind shear effect on the aerodynamic performance and structural performance of wind turbines are researched.The influence of wind shearing effect on the aerodynamic load and fatigue life of large wind turbines is revealed,which provides a reference for the subsequent blade structure design. |
PDF Full Text Request