Research On Modeling And Grid Generation Methods For Offshore Wind Turbine Blades

As wind turbines move towards the deep sea,it is of great significance to explore the impact of blade air-elastic properties on the operation of wind turbines and conduct high-precision simulation of large-scale offshore wind turbines.This article takes DTU-10MW wind turbine blades as the research object,and conducts relevant research on offshore wind turbine blade modeling and grid generation methods.The main content of the paper is:(1)A modeling method of wind turbine blades based on STL format of general geometric modeling file is proposed.Generate spatial triangular patches through scattered points on the blades,directly generating a three-dimensional STL model of the blades.Based on the open source mesh generation program SnappyHexMesh,an automatic mesh generation method based on SnappyHexMesh is developed.The grid quality is adjusted in advance by preset parameters,the SnappyHexMeshDict dictionary file is automatically output,and the blade flow CFD calculation grid is automatically generated by script.The proposed method was used for modeling and CFD numerical simulation of DTU-10MW,and the error of power and thrust comparison results under various operating conditions was within 10%,verifying the accuracy of the modeling and grid generation methods.(2)Explored the possible vortex-induced vibration phenomenon of the blade tip position airfoil when the wind turbine pitch fails.When the airfoil is at a 90° angle of attack,periodic vibration along the chord occurs due to the influence of periodic fluid forces.At a wind speed of 5m/s,the vibration frequency of the airfoil is close to the fixed vortex shedding frequency,causing resonance.As the incoming wind speed increases,the vibration amplitude increases,and the vibration diverges when the incoming flow speed reaches the cutoff wind speed.(3)The related research on finite element modeling methods for offshore wind turbine blades was conducted,and a finite element modeling method based on the open source finite element software GMSH was proposed.After quality verification and blade inherent characteristics verification,the error between the quality of the blade finite element model and the DTU-10MW reference unit is less than 2%;The error between the first 5 modes of the blade and the DTU-10MW reference unit is within 5%,which proves the accuracy of the blade finite element model.This paper studies the preprocessing methods suitable for CFD simulation and finite element analysis of ultra large wind turbines,which are used to study the aerodynamic and structural characteristics of 10 MW wind turbines.The research in this paper provides a reference for the refined numerical simulation method of ultra large wind turbines.