Wind Tunnel Experiment on Improving Efficiency of Low-Re Number Grid Turbulence Generation Focusing on Cross-Sectional Geometry of Grid Bars

抄録

The aim of this study is to investigate the efficiency of turbulence generation using turbulence grids, focusing on the cross-sectional shapes of the grid bars. Efficiency in this context refers to maintaining the intensity of velocity fluctuations in the generated turbulence while reducing the drag coefficient of the turbulence grid. Wind tunnel experiments were conducted using turbulence grids with three different cross-sectional shapes (circular, square, and rectangular), and the velocity fluctuation intensity and drag coefficient of the generating grids were measured. The results showed that the turbulence grid with square and rectangular cross sections produced higher velocity fluctuation intensities higher than those with circular cross sections, and the distributions of these intensities were consistent between the two shapes. In addition, the turbulence grid with a rectangular cross section had a drag coefficient about 10% lower than that of the square cross section. These results suggest that a rectangular turbulence grid may be more efficient at generating turbulence.