Wind Induced Vibration Response Analysis And Vibration Reduction Optimization Of Frame Lightning Rod Based On Bidirectional Fluid Structure Coupling

In order to prevent the substation structure from being damaged by lightning,people usually install the lightning rod on the substation frame to form the frame lightning rod structure.Because the height of the structure is usually between 10 m-30 m and the working environment is mostly in the suburbs,the wind load becomes the main load.In this paper,the fracture accident of 220 k V frame lightning rod in a 500 k V substation is taken as the engineering research background,and the interaction between frame lightning rod and wind is studied by using two-way fluid structure coupling numerical simulation method.Finally,an optimization measure is proposed to optimize the vibration reduction design of frame lightning rod.The main research contents are as follows(1)This paper systematically and comprehensively reviews the development of fluid structure interaction and vortex induced vibration,summarizes the research status of vortex induced vibration suppression at home and abroad,leads to the research purpose of this paper,and finds a kind of spiral side plate layout parameters which can not only suppress the vortex induced vibration of lightning rod to the greatest extent,but also have no great adverse effect on the structure along the wind direction.(2)Using ANSYS Workbench 19.1 analysis platform to construct two-way fluid structure coupling analysis,the wind-induced vibration response characteristics of the prototype frame lightning rod under different wind directions are analyzed.The results show that the cross wind vortex induced resonance phenomenon will appear in Sections I,II and IV of the frame lightning rod under each wind direction,and the resonance locking interval is 12.64 m/s-25.30 m/s.When the wind speed reaches 22.13 m/s,the first section of the frame lightning rod reaches the resonance amplitude.When the wind speed is 18.97 m/s,the second and fourth sections of the frame lightning rod reach the resonance amplitude.(3)When the vortex induced resonance occurs,the cross wind response of the first section of the lightning rod is even greater than that of the cross wind response.It can be seen that the cross wind effect of the structure must not be ignored in the design stage.(4)Based on the analysis of the wind-induced vibration response of the lightning rod of the prototype frame at each wind direction angle,it is found that the interface of section III and Section IV of the structure in the downwind direction is at the position of strain mutation,and the stress is relatively unfavorable,so it needs to be checked in the design and use stage.The cross wind response has a great influence on the I and II sections of the structure,which can be taken into account when considering the vortex induced suppression measures.(5)The data of strain and top displacement of lightning rod with different parameters of spiral side plate are extracted,and the vortex suppression efficiency of spiral side plate with different parameters is compared.It is found that the best vortex suppression efficiency is obtained when the pitch of spiral side plate is 8D(D is the diameter of riser)and the coverage rate is 30%,and there is no effect on the windinduced vibration response along the wind direction Too much influence.