円柱から発生するカルマン渦音の低減法に関する研究 : 短い円柱を交差させることによる減音効果 : 流体工学 , 流体機械

概要

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Karman-vortex induced sound is generated from a cylinder in a uniform flow and causes serious noise problem. Recent papers described that the sound was reduced efficiently by attaching another cylinder (called No.2 cylinder) in downstream side to the cylinder (called No.1 cylinder). In this report, we examined the effect due to the length of No.2 cylinder, the intersectional angle between two cylinders and the upstream positioning of No.2 cylinder. It was clarified that the noise reduction in case of upstream positioning is greater than that of downstream positioning. In order to clarify the reason of the noise reduction, we measured the coherence function γ between the fluctuating pressure on the surface of No,1 cylinder and Karman-vortex sound measured far from the cylinders. As a result, it was revealed that the turbulence from No.2 cylinder promotes the dispersion of the dominant frequency of the fluctuating pressure on No.1 cylinder.
2001-03-25