| Wind power generation is one of mature technologies of renewable power.China is abundant in wind power resources.Since 2010,installed capacity of wind power has been ranked first in the world,and it is planned to realize wind power generation capacity of 200GW in 2020.As the poor working environment of the wind turbine,it occurs in the tower connecting section of the welded joints at the fatigue fracture,the tower on the joint bolts fatigue loose,tower instability collapse and so on are common.These phenomena each year causes the great economic losses,restricting the exploration and application of wind energy,Tower as a wind turbine support,once the tower damaged will threaten the entire wind turbine,blades and other related equipment security.Based on FLUENT computational fluid dynamics software,this paper conduct the numerical simulation of wind load on the surface of wind turbine is carried out for the specific 1.5WM wind turbine project.The wind load obtained from the simulation is added to the dynamic finite element analysis of the wind power tower.Through the ANSYS time history calculation,the fatigue damage parameter of the most dangerous point of the wind power tower is calculated by the rain flow counting method.Finally,the tuned mass damper is used to discuss the vibration of the wind power tower,and the fatigue life of the wind power tower is prolonged.The main research of this thesis is as follows:1?The aerodynamic model of NREL Phase VI wind turbine is simulated by two kinds of turbulence models based on S-A and K-Epsilon.Five wind speed conditions were calculated from 7 m/s to 25.1 m/s.Under the wind speed condition of 7 m/s and 25.1 m/s,the error of the shaft torque calculated by the two turbulence models is less than 10%.The wind speed is 10 m/s,13.0 m/s and 15.1 m/s,the error of the shaft torque calculated by the two turbulence models is less than 20%.2?The finite element model of structural dynamics based on the specific project of wind power tower is established.According to GL2010 certification standard,the ultimate strength of the tower connection is satisfied in the transient analysis.Using FAT112 as S-N curve,the stress cycle of critical damage surface is extracted by rain flow counting method.Using the theory of linear damage accumulation,the most dangerous fatigue point of tower is obtained at the second welding node,the fatigue life of tower is 18.14 years,can not reach 20 to 25 years of service life.3?The TMD vibration reduction system with different frequency ratio,mass ratio and damping ratio is studied by ANSYS.When using different damping evaluation indexes,the optimal value of vibration design parameters is different.And when the fixed mass ratio is 0.05,choose the displacement and acceleration as the indexes of vibration reduction,the optimal ratio of frequency is respectively 0.80 and 0.95,the damping ratio is respectively 0.12 and 0.09,the displacement damping rate and the acceleration damping rate are respectively 32.92%,29.34%,the vibration response effect of the structure is obvious.4?The TMD vibration reduction system is very helpful for the extension of the fatigue life of the tower,whith is ascribed to the work of the damping system can reduce the stress amplitude of the tower.When the optimum damping system with mass ratio of 0.05 is set,the fatigue life of the tower is 273.79 years.The life extension is 15.09.After the damping system is installed,the fatigue life of the tower is much greater than that of 20 to 25 years.The mass ratio of TMD damping system has a great influence on the damping effect,and the influence is positively correlated.If the fatigue life of the tower is greater than 20 to 25 years,the mass ratio is greater than or equal to 0.01,due to the limit of TMD,the damping ratio needs to be 0.21 or more. |
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