Simulation Of The Downburst Wind Field And Analysis Of The Damage To The Transmission Tower-Line

Downburst is an instantaneous wind under the thunderstorm, its wind profile is different from the boundary layer winds, and the wind field characteristics have significant correlation with topography. The collapse accidents of transmission towers caused by downburst have occurred now and then. In order to improve the transmission tower’s ability of bearing downburst, it’s necessary to study the wind field of downburst, and simulate the wind-induced collapse process of the transmission tower-line system. Based on the downburst wind field model and 110 KV real transmission tower-line system built in this paper, different terrain of downburst wind field and analysis of the mechanical response of tower-line structure under downburst wind are discussed.In this paper, different topography downburst models are established firstly, and a structured grid is calculated by FLUENT. Then comparative analysis of the vertical wind profile at various radial distance and the radial wind profile at different height of plains, hills and mountain terrain is done, and the influence of gradient on the wind field is discussed. And then the 110 KV actual transmission tower model and transmission lines model with different span are established based on the parabola theory. The “two towers and three lines” finite element model is built by coupling the tower and lines model. After then, the analysis of the displacement of the tower-line under gravity is done and the accuracy of the modeling is verified. And according to the material nonlinear theory, the damage process of the transmission tower and tower-line structure under downburst is studied. Finally, the damage process under different situation is compared by changing terrain, wind direction angle and span.Research results show that the effects of the terrain on downburst wind field are obvious. In these three types of terrain, the hilly terrain wind velocity value is greatest, and the height of the maximum wind velocity position is lowest, and the wind resistant ability is weakest. For slope and hill terrain, the maximum wind velocity increases with the terrain gradient, but the height is lower. The wind direction angle and span of the tower-line are also significant effects to the wind resistance ability of the tower-line. The skew wind has stronger destructive power to the tower-line structure than the 90 degrees wind, and the wind resistant ability of tower-line system has declined by increasing the length of the span.