Optimal Design Of Composite Blade Layering For Horizontal Axis Wind Turbines

With the global energy shortage and environmental pollution becoming more and more serious,renewable energy gradually attract worldwide attention.As one of the main production modes of renewable energy,wind power generation has developed rapidly in recent years.Blade is the key component of wind turbine to capture wind energy.The alternating bending,torsion and forced vibration of blade in operation will cause fatigue damage,even cause transverse breakage,affecting the normal operation of the unit.Therefore,it is of great theoretical significance and engineering application value for the safe operation of wind turbines to study the structural performance improvement of blades.Firstly,the stress and strength ratios of composite components are solved based on analytical method and finite element method,and the results are compared and analyzed,Secondly,ANSYS software is used to establish the parametric model of the blade before and after airfoil optimization,and its structural performance is analyzed.Then,by analyzing the influence of the change of multi-layer parameters on the blade structure performance,a design method with the ply angle as the optimization variable is proposed.Finally,the lamination optimization of blade sections at different positions is carried out,and the effects of lamination optimization on blade modal and static characteristics are studied.The multi-section lamination optimization scheme of blade is determined,and the natural frequencies of blades before and after optimization and the maximum displacement and stress of blades under different conditions are solved and compared.The main research work and achievements are as follows:(1)The stress and strength ratios of each layer of composite members under three basic deformations,tension,compression,bending and torsion,are solved by using the formulas of stress and strength ratios derived from the mechanics of composite materials and the finite element method respectively,and the results are compared and analyzed.The results show that the stress and strength ratios of each layer obtained by the two methods are basically the same,which verifies the correctness of the geometric modeling,laying method,constraints and load definition by using ANSYS program in this paper.(2)Using ANSYS finite element software,the parametric model of 2MW wind turbine blades before and after blunt trailing edge airfoil optimization was established,and the structural performance was compared and analyzed.The sensitivity of blade structure performance to multi-ply parameters was studied by setting different ply schemes.The results show that the optimization of blade airfoil has an effect on the structural performance of blade,but the lifting effect is not significant.The change of lamination angle can improve the natural frequency of blade,reduce the relative displacement,maximum stress and maximum displacement,and effectively improve the structural performance of blade.(3)Taking the ply angle as the optimization variable,the minimum strength ratio as the optimization objective,and the maximum displacement as the constraint condition,the blade ply optimization model was established.Particle swarm optimization(PSO)is used to optimize the lamination of blade sections at different locations.The natural frequencies,maximum displacements and maximum stresses of blades before and after optimization are compared,and the effects of lamination optimization at different locations on the structural performance of blades are analyzed.Based on the above analysis results,the optimization scheme of multi-section pavement is determined,and the structural performance of blades under different conditions before and after the optimization of pavement is compared and analyzed.The results show that the maximum stress and displacement of the blade decrease obviously with the optimization of the lamination of the blade root section,the natural frequency of the blade increases obviously with the optimization of the lamination of the middle section of the blade,and the structural characteristics of the blade change little with the optimization of the lamination of the blade tip section.The maximum stress and displacement of the blade under different working conditions are reduced after multi-scction lamination optimization,which verifies the effectiveness of the optimization.