Analysis of an Electrical Transmission Tower by CFD: A Comparison to the Mexico Standards

Place and duration of Study: Faculty of Engineering, Autonomous University of Queretaro, January 2022 to May 2023.

This study analyzed wind pressures in two ways: first, according to current Mexican standards, and second, by performing a dynamic wind analysis using Computational Fluid Dynamics (CFD).

The present study focused on analyzing the transmission tower E71W21, which is commonly used as a suspension tower in Mexico. This tower has a height of 46.9 m and a base of 12 m, and is similar to the type of towers that collapsed in the city of Los Cabos, Mexico, by the passage of Hurricane Odile in 2014.

Current regulations establish that transmission line towers may be out of scope and must be designed with particular specifications for each case, by numerical models and experimental studies in the wind tunnel.

Two models were made, the first model which consisted of dividing the tower into 5 parts, in order to reduce the computational cost. The model was detailed by modeling the bars with their corresponding section and simplified to the most predominant thickness of the section. The second model is the complete tower as a rigid solid without distinction between the elements.

The wind pressure values obtained using the current standards in Mexico and according to specification J100-50 were found to be 15-20% lower than the values obtained from the CFD simulation results. The difference can be presented by the mesh quality, turbulence model used, or simplifications by the need to reduce the computational cost. The analysis results are presented graphically as pressure and velocity contours, as well as streamlines.

Computational fluid dynamics is a very useful tool for simulating physical experiments such as in a wind tunnel, although it cannot replace the need for physical experimentation. With the help of high-performance computers, Computational fluid dynamics models offer a detailed exploration of physical phenomena.