抄録
Aerodynamic sound produced by an object in a flow is reduced by adding a porous material on the object. The sound and the force exerted on a cantilevered cylinder had been measured simultaneously to investigate the relationship between the sound and the force as well as the effect of the porous material. However, vibration of the cylinder had easily occurred since the cylinder was supported at one end. In this study, the support point of the cylinder was increased from one end to both ends in order to avoid the vibration. The cylinder was set in a low-noise wind tunnel of which nozzle outlet was 150 mm wide and 100 mm high. Two cylinders were used: one was a bare cylinder of 30mm in diameter; the diameter of the other cylinder was the same but the surface was replaced by a three-layered mesh. The sound and the fluctuating lift force were reduced by the mesh. The rate of reduction in aerodynamic sound was comparable to that in fluctuating force for wide frequency band. In spite of the similarity in reduction between the sound and force, the coherence between them was quite low. Averaged drag coefficients of the two cylinders were almost same.
