Research On Loads Analysis And Stability Characteristic For MW Wind Turbine Composite Blades

Wind energy is regarded as a renewable and green energy of clean environment protection,which makes a significance contribution to adjust energy structural,to reduce pollution and to solve petrochemical energy shortage.Since 21 th century,with the sustained development of wind power technology,it is obviously that the tendency of the large wind turbine blade.In particular,the blade carries aerodynamic force,inertial force and gravity load and so forth during the operation process of wind turbine.In that case,the blade is easily take place instability,even to fracture failure.To some extent,it will bring in economic losses for the country and community.According to the characteristics of wind resources and environment in Hexi area of Gansu Province,regional wind loads mathematical model is developed,the loads change regulation under ice overlying and clean working conditions and the instability mechanism of the blade are explored.Furthermore,it provides a theoretical reference that investigating regional blade structural design.The main research efforts in this dissertation can be expressed as follows.(1)Establishing wind loading model of Hexi Region and calculating the blade loading under the ice overlying and clean conditions.This paper aims to the typical characteristics of wind resources in Hexi Region,developing the corresponding wind loading and blade ice overlying models.Considering the effects of the turbulent and vertical wind shear,exploring the steady and dynamic loads change regulation and vibration characteristic for the wind turbine blade under the ice overlying condition.Results shown that ice overlying results in increased loads and lower vibration frequencies.There results will provide certain theoretical significance to blade optimization design and to structural strength check.(2)A finite element model of the baseline blade was created in ANSYS software,and then analysis static performance of 1.5MW wind turbine blade.The composite blade actual laminate designs are finished based on the equivalent design method and the Capitel curve design method.The finite element model of the blade is created based on the finite element platform.The rigid coupling loading method is adopted when the load loading.The stress and strain contours of the blade at the rated wind speed are achieved by static analyzing.Furthermore,it revealed that the finite element model of blade is rationality,which lay a foundation for the further studying on the stability of the blade.(3)The calculation methods of pre-stress modal and bucking stability are also discussed for the 1.5MW blades.The natural modes and frequencies of the blades are calculated by using Lanczos method under the pre-stress effect conditions,then the vibration characteristics of the blade is studied at the rated wind speed.Furthermore,the effect of the pre-stress effect on the vibration characteristics of the blade and the effect of rotor speed on the frequency of the blade are studied.Based on the results of static analysis,the buckling stability characteristics of the blade are discussed by numerical simulation method.It mentioned above results illustrated that the blade does not occur overall instability at the rated wind speed conditions,so it meets the overall stability requirements.However,the blade taken place local instability at the maximum chord section as the load gradually increases.The results will provide a reference to regionalized blade optimization design and to lay a corresponding foundation in the aspects of the engineering applications.