Research On Modeling And Isogeometric Analysis Of Complex Surface Of Horizontal Axis Wind Turbine Blades

At present,the traditional wind turbine blade aerodynamic shape modeling and structural characteristics analysis mostly use different basis functions,so that the movable boundary of the blade and the structural analysis model have large errors,which in turn affects its calculation accuracy and solution efficiency.The isogeometric analysis uses the same basis function to realize seamless connection between the blade geometry and the structural model,NURBS control vector of the blade aerodynamic shape can be directly used as the blade structure control parameter.Therefore,this paper introduces the isogeometric analysis into the complex blade aerodynamic shape modeling and the finite element analysis of the blade structure.The main contents are as follows:This article first discusses the design method of wind turbine blades.Based on the blade two-dimensional airfoil and three-dimensional blade functional integrated expression theory,the unified three-dimensional integrated expression of wind turbine blades with variable chord length and variable twist angle is completed.Finally,the relevant program for blade surface design is written.Nine airfoil data are the basis of the design,the blade shape distribution and chord length distribution are fitted,41 leaf element data are calculated,and the design of the shape of the wind turbine blade is completed,which provides data support for the NURBS modeling of the blades later.Then this article analyzes the expression form of B-spline and NURBS curve,surface.The previous method of directly modeling with data points is abandoned.The NURBS node control vector program is wrote,the 41 NURBS control points of leaf elements are calculated,these are used to complete the NURBS surface model of the wind turbine blade.Compared with NURBS,T-spline can reduce a large number of redundant control points.It uses multiple planes to intersect with the NURBS model,thousands of wind turbine blade element data are obtained,then a wind turbine blade T-spline surface model is designed,it is regarded as the experimental object of isogeometric analysis.Finally,the T-spline surface model of the wind turbine blade is imported into the isogeometric analysis and collaborative design platform,the displacement and strain cloud diagram of the blade and the trend of the maximum value over time are obtained.Then the same model is imported into the finite element software abaqus for comparative analysis.The research shows that the two methods have a maximum displacement error of 6.133% and a maximum strain error of 6.277%.The displacement and strain of the maximum point change linearly with time,the straight slope of K value is approximately the same,thus these verify the correctness and feasibility of the isogeometric analysis method.The modeling and analysis based on isogeometric analysis proposed eliminates the processing process from complex blade CAD model to CAE model,improves calculation efficiency,satisfies calculation accuracy requirements,and has certain application value and research significance.