The effect of fine scale turbulence on the corner vortices of a rectangular prism

Strong winds produced in storms and hurricanes have a destructive effect on buildings, particulary on low-rise structures such as industrial complexes. The damage often starts when the roof is teared off because of strong suction pressures which are produced near corners and edges by the turbulent winds of the atmospheric boundary layer. When the wind approaches the corner, two vortices which generate extreme negative pressures, are formed.

A number of work has been conducted on the effect of turbulence on the corner pressure field of low-rise buildings. However, there is still a need to investigate the effect of the finest turbulence scales.

An experimental programme, which is the final part of a Master of Science in Mechanical Engineering, was conducted to investigate the effect of fine scale turbulence on the corner vortices of a rectangular prism, which is a common representation of a low-rise structure. Experiments were conducted in a wind tunnel using grid and rod configurations to produce turbulent flows.

The results from the grid generated turbulence show that both increasing turbulence intensity and length scale increase the pressure coefficients, although the mean pressure is reasonably constant for varying turbulence length scale. Considering the finest turbulence scales, which were induced by the rod, the largest effect was found when the rod was positioned in the lateral direction slightly under the leading edge. Then, the fluctuating pressure coefficient increased and the pressure field under the corner vortices started to fluctuate at a frequency of 240 Hz, which is an interesting phenomenon.

Author: Sandberg, Marcus

Source: LuleƄ University of Technology

Download Link: Click Here To Download This Project Report (PDF)

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