Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 54 5 2022 07 23 Experimental Study of Impact Angle of Microburst Effects on a Cubic Structure – Part A: Stationary Microburst Observation Experimental Study of Impact Angle of Microburst Effects on a Cubic Structure – Part A: Stationary Microburst Observation 961 984 4687 10.22060/mej.2022.20500.7250 FA Mohammad Hojaji Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran 0000-0002-6385-7859 Nima Asgari Department of civil engineering, Najafabad branch, Islamic Azad University, Najafabad, Iran Saied Jalil Hosseini Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran Amir Hosein Rezvani Department of civil engineering, Najafabad branch, Islamic Azad University, Najafabad, Iran Behshad Sharifzadeh Department of civil engineering, Najafabad branch, Islamic Azad University, Najafabad, Iran Journal Article 2021 09 08 A Downburst can produce divergent outﬂow wind on the ground surface, which is different from the behavior of atmospheric boundary layer flows. In this research, the effects of downburst on a cube-shaped structure in two different directions of flow (α), four different ground surface angels relative to the downburst direction (θ), and different radial distances (X/D) relative to the downdraft center were investigated by a simulator that was made for this thunderstorm. Simulation of this flow is created by a blower whose task is to uniformize the flow created by the fan embedded behind it. The velocity and turbulence intensity of flow was measured at different X/Ds. also, the distribution of pressure coefficient on the sides of the model was measured at the X/D locations. In addition, a good agreement has been observed between the data comparison of this study and previous studies. It was observed that at the center of the downburst for all θs, the structure has a positive pressure coefficient along its sides. By moving away from the center of the storm, the flow behavior is similar to the boundary layer flows. By increasing θ, it was found that the difference of pressure coefficient between the windward side relative to the roof and the backward sides, increased, which in the worst case has changed by about 80%. By examining the direction of flow to the model, it was found that the force coefficients when the model is at α=45°, are about 35% less than when the model is at α=0°. Finally, it was found that at X/D=1, the maximum force coefficient is applied to the structure. A Downburst can produce divergent outﬂow wind on the ground surface, which is different from the behavior of atmospheric boundary layer flows. In this research, the effects of downburst on a cube-shaped structure in two different directions of flow (α), four different ground surface angels relative to the downburst direction (θ), and different radial distances (X/D) relative to the downdraft center were investigated by a simulator that was made for this thunderstorm. Simulation of this flow is created by a blower whose task is to uniformize the flow created by the fan embedded behind it. The velocity and turbulence intensity of flow was measured at different X/Ds. also, the distribution of pressure coefficient on the sides of the model was measured at the X/D locations. In addition, a good agreement has been observed between the data comparison of this study and previous studies. It was observed that at the center of the downburst for all θs, the structure has a positive pressure coefficient along its sides. By moving away from the center of the storm, the flow behavior is similar to the boundary layer flows. By increasing θ, it was found that the difference of pressure coefficient between the windward side relative to the roof and the backward sides, increased, which in the worst case has changed by about 80%. By examining the direction of flow to the model, it was found that the force coefficients when the model is at α=45°, are about 35% less than when the model is at α=0°. Finally, it was found that at X/D=1, the maximum force coefficient is applied to the structure.

https://mej.aut.ac.ir/article_4687_fc152e73692bc3c934d248f639d9e963.pdf