Experimental and numerical studies on Aeolian tone from D-shaped cylinder

Aeolian tone generated from a D-shaped cylinder in a stream was studied experimentally and numerically for various width-to-height ratios of the cross-sectional shape. The sound pressure level and unsteady fluid forces were measured experimentally for a circular cylinder and D-shaped cylinders with width-to-height ratios of 0.5, 1, and 1.5. The experimental results revealed that the Aeolian tone and lift fluctuation of the D-shaped cylinders were smaller than those of the circular cylinder. Flow structures around the circular and D-shaped cylinders were investigated by using large eddy simulation to understand the mechanism of the reduction of Aeolian tone from the D-shaped cylinders. The numerical results indicated that the D-shaped cylinder with a width-to-height ratio of 0.5 showed similar velocity fluctuations with the circular cylinder, but the shortening of the streamwise length resulted in a reduction of the sound pressure level. Moreover, the velocity fluctuations in the wake decreased in the D-shaped cylinders with width-to-height ratios of 1 and 1.5, resulting from suppression of the vortex shedding near the cylinder.