| In recent years,the collapse of wind turbines occurred frequently.As an important loadbearing structure of large-scale wind turbines,wind turbine towers directly affect the stability and reliability of wind turbine operation.In order to ensure the safety,it is necessary to pay attention to the vortex-induced vibration and fatigue problems of the tower under wind load.This paper takes a certain MW-class wind turbine tower as the main research object.Aiming at the vortex-induced vibration problem in the application of wind power towers,a new tower structure with ribs on the surface of the tower is proposed.Combining the finite element analysis method,engineering specifications,and experimental methods to analyze the influence of the rib parameters on the vortex-induced vibration and fatigue strength of the tower,and obtain a new stiffened tower that can reduce the vortex-induced vibration and meet the fatigue strength requirements.(1)Effect of spoiler on fatigue strength of sheet metal.Select a section of the wind turbine tower and unfold it into a flat plate.Under the condition of equal plate quality,according to the finite element method,the effect of the rib parameters on the fatigue strength of the stiffened plate is analyzed.Compared with ordinary plates,the optimal rib parameters applied to the plates are obtained.(2)Analysis of vortex-induced vibration characteristics of tower cylinder model.Apply the optimal rib shape obtained on the plate to the stiffened tower.Through ANSYS+CFX fluidstructure coupling method simulation calculation,the vortex-induced vibration change law of the stiffened tower under different rib angles is obtained.And compared with the ordinary tower,the optimal rib shape that has the best suppression effect on the tower vortex induced vibration is obtained.(3)The experimental model was established for wind tunnel test.The optimal rib shape and simulation model obtained in the first two chapters were scaled and applied to the wind tunnel experimental model.The accuracy of numerical simulation results of VIV is verified.The variation law of vortex induced load on the surface of two models was measured,which provides a prediction trend for fatigue simulation.(4)The fatigue simulation calculation and life evaluation of wind turbine drum are carried out.Combined with the results of small wind tunnel experiments,Davenport power spectrum and linear filtering method are used.Based on the Autoregressive model,the MATLAB program was written to simulate the time history and wind load of the wind turbine drum pulsating wind speed.According to the simulated wind load,the fatigue comparative analysis of the two models is carried out.The stress time history curve at the hot spot of the stiffened tower is obtained,and the variable amplitude load spectrum of the stiffened tower is obtained.According to the S-N curve and fatigue theory,the fatigue life of the stiffened tower is evaluated.Research shows: Adding turbulence ribs on the surface of the tower can effectively weaken the frequency of the vortex-induced vibration of the tower.At the same time,the fatigue strength of the stiffened tower is lower than that of the ordinary tower,but the life of the stiffened tower still meets the requirements. |
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