Aerodynamic Evaluation and Modification of Tehran International Tower Section Exposed to Annual Winds

The study of wind flow around tall towers is of particular importance due to the asymmetric vortex shedding and the consequent vortex induced vibrations into the structure. In the present study, the numerical simulation of the wind flow over the cross-section of the 56-store Tehran International Tower is performed and the aerodynamic force coefficients and oscillation frequencies and amplitudes are calculated. Then, by presenting a new method of combining average values and amplitude of fluctuations of aerodynamic coefficients at each wind velocity and direction, as well as applying the annual wind probability in Tehran, a criterion for aerodynamic evaluation of Tower exposed to annual winds is presented. Numerical calculations are performed using unsteady incompressible flow and k-ω SST turbulence model.The most critical wind speeds and positions on the tower in terms of the sum of the average coefficients and their ranges of fluctuations is detected at the directions of 0 and 20 degrees at wind speeds of 15 and 10 m/s, respectively.In order to improve the aerodynamic properties of the tower, geometrical modifications are made and its aerodynamic force coefficients are calculated. Based on the obtained results, the corrected geometry in all wind blowing directions has a lower total aerodynamic force coefficient than the original geometry and causes an average reduction of 21% of the total aerodynamic force coefficients compared to the original geometry.