| EHV transmission towers often face the problem of resonance with the incoming wind in the natural environment,which is very serious and must be avoided.When the incoming wind blows over the tower,a series of continuous vortex streets will be generated downstream,and the accompanying lift and drag forces will act together on the tower to cause it to vibrate.In extreme cases,the severe vibrations will force the tower to appear damaged,which is an urgent problem to be solved.In this context,this paper uses CFD(Computational Fluid Dynamics)technology to carry out vortex-excited vibration studies on simplified two-dimensional and three-dimensional cylinders respectively,and to suppress the vibration problem of lattice steel tube towers by designing a new type of variable-section helix.It is mainly divided into the following aspects:(1)In the 2D CFD calculation,this paper firstly focuses on the accuracy and efficiency of the calculation to determine the conditions of the calculation grid type and size,calculation time step,boundary conditions,turbulence model,and wall functions.Secondly,the validity of the CFD mesh settings is verified by citing the experimental data from previous published literature to verify the flow characteristics of a single cylinder under specific operating conditions.Finally,the flow-structure coupling mechanism of the steel tube vortex vibration is revealed by analyzing the vortex vibration phenomenon of a single cylinder.(2)Based on the simulation of single-cylinder vortex excitation vibration,a helix is wound around a smooth cylinder,and the effect of different cross-sectional shapes of the helix on suppressing the cross-wind vibration of the steel pipe is considered,and its vibration mechanism and flow field characteristics are analyzed,and it is found that a semi-circular shape is the optimal cross-sectional shape of the helix for vibration damping.(3)Based on the semi-circular cross-sectional spiral,the influence of different cross-sectional dimensions on the spiral line to suppress the cross-wind vibration of the steel pipe is considered.Through the calculation found that the different cross-sectional size of the spiral line has an important impact on the inhibition of steel tube crosswind vibration,in this paper,the study of 2mm ～ 7mm conditions,found that before 5mm,the larger the cross-sectional size of the spiral line,the better the inhibition effect,5mm for the study of the best vibration damping cross-sectional size,more than 5mm damping effect is almost unchanged.(4)On the basis of two-dimensional numerical simulation,this paper designs a new type of variable-section spiral line spoiler with multiple suppression functions for cross-wind vibration of lattice steel tube tower inclined webs,and the entire spiral line cross-section gradually and continuously changes from thin to thick from the top to the bottom of the steel tube.In order to verify the better vibration damping effect of the variable-section spiral,a traditional equal-section spiral spoiler is designed,and the two are wound on the same smooth cylinder for three-dimensional two-way fluid-structure coupling numerical simulation.(5)In the three-dimensional fluid-structure coupling numerical simulation,the vibration mechanism and flow field characteristics of smooth cylinder,wound equal-section spiral cylinder,and wound variable-section spiral cylinder are explored respectively,and their vibration responses are compared,and it is concluded that both equal-section spiral and variable-section spiral can effectively suppress the cross-wind vibration of steel pipe,but the vibration reduction effect of variable-section spiral is more significant than that of equal-section spiral under the same conditions.more significant. |
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