Numerical Study of Ultra-High Voltage Transmission Tower Wind Loads Characteristics Against Tornado

In this paper, the wind load characteristics of the Ultra-High Voltage transmission tower under tornado are studied based on the CFD (computational fluid dynamics) numerical simulation method. The numerical model of a full-scale tornado is established. The measured radar data of Spencer tornado as the velocity inlet are adopted to generate the tornado-like wind field, and the impacts of the surface roughness are considered. The tangential velocity and core radius at different heights are obtained, then contrasted with the measured data to verify the rationality of the tornado-like vortex structure. Next, the overall refined CFD numerical modeling of the transmission tower is established, then the SST k-ω turbulence model based on RANS is used to simulate the flow around the transmission tower under tornado. The effects of the different locations and wind directions on the shape coefficients of each section of the transmission tower are studied. It is found that the wind loads of the top section 1 to section 4 of the transmission tower would take the maximum when the tower is located at the wind field of 1.5D (D is the core radius), and the wind loads of the bottom section 5 to section 9 of the transmission tower are the maximum when the tower is located at the wind field of 1.0D. The wind loads of transmission tower reach the maximum when the tower is located at the wind field of 1.0D. The worst wind attack angle of the transverse directions of the transmission tower increases from 60° to 90°, and the worst wind attack angle of the longitudinal directions of the transmission tower varies in the range of 0° to 30° as the distance from the center of tornado increases. The simulated wind load shape coefficient of the transmission tower at the locations of 1.0D and 1.5D are larger than the code values, and all sections (except for the section 7, 8 and 9 at the location of 1.5D) are also larger than the code values.