| As a kind of clean and renewable energy,wind energy has broad prospects for development.The natural wind changes in the wind wheel wind load is not timely,not uniform effect on the wind turbine,the flow field changes will cause changes in the structure of the wind wheel,which is an important incentive of side wind factors to change the dynamic characteristics of blade.Therefore,it is an important research topic to find out the mechanism of the influence of the side wind on the wind turbine.In this paper,a numerical method based on transient analysis to analyze the dynamic characteristics of blades is presented.Through the construction of wind turbine transient coupled system and computational fluid dynamics CFX module,a wind turbine airfoil full size physical modeling,the mesh generation method for regional encryption ",to capture the distribution characteristics and evolution of the flow field,qualitative and quantitative analysis of the unbalance response of aerodynamic excitation wind wheel structure the characteristic parameters,to reveal the condition of side wind effect on dynamic response of the blade structure.The main content of this paper is divided into the following three aspects:Firstly,with the help of vortex cloud data,vortex on the near wake of tracking and recognition,the vorticity concentrated area number as the basis of judging,found to have multiple vortex frequently appear and disappear,and generated in the rudder side near the center of vortex are scattered in the area far from the center of the side of the vortex although the generation of downstream consumption;two times the diameter of the wind wheel is more vorticity concentrated area,but the area of vortex energy is weak,so it is not the main distribution area of vortex field energy.Axis always flow when the upstream and downstream vortex dissipation number had no significant difference;when the side wind angle at 20°~30°range,rudder tip vortex propagation region into the frequency of tip vortex shedding characteristics caused by vortex center and tip vortex frequent interaction,the stable structure of the tip vortex is not easy to maintain.That its life cycle is shortened,at the same time,the amount of concentrated area of high strength vortex rudder nearby,so that the wind wheel and the wind angle becomes smaller,forcing the wind wheel wind,reveals the automatic air removal device on the wind wheel deflection torque than a regulation mechanism of small wind turbine.Secondly,the deformation of the tip is the characteristic parameter which can reflect the change of the leaf structure field,the study found that different side wind angle,tip axial displacement variation with azimuth angle is not simple sinusoidal,the axial displacement data processing of the blade tip is done by means of polynomial fitting,the axial displacement is four times the dynamic response of the polynomial;although different coefficients of side wind angle tip axial displacement fitting polynomial is different,but the fitting curves obtained are four polynomials.At the same time,the analysis of wind wheel rotating plane flow field parameters reveals how both side wind angle,azimuth angle of blade rotation to 120°~240°of tip axial displacement can cause the minimum value,because the tower flow field around disorder offset part of wind load.Finally,according to the condition of side wind turbine vortex near wake flow field distribution,combined with the dynamic response of structure reveals the tip,tip vortex and tip axial displacement is positively related,not linear relationship;quantitative analysis to the relevance of the two,introducing the concept of "the worst wind angle,the definition of" side wind angle of 20 degrees is crosswind angle displacement maximum axial tip.The wind tunnel test is used to verify the analysis result,and the error of numerical calculation can be controlled within ±8.5.The accuracy is good,and the reliability of the conclusion is proved. |
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