104 物体表面への多孔質材適用による空力音低減手法 : 第2報後流と吸音特性の測定結果(2)(OS1-1 流れの抵抗低減,OS1 流れの抵抗抵減,オーガナイズドセッション)

概要

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Aerodynamic noise from bluff bodies is well reduced when they are covered with porous materials. To clarify this mechanism we measured wake velocities behind a cylinder covered with porous material by the particle image velocimetry (PIV) technique and characteristics of sound absorption of porous material by using pressure transducers and a loud speaker. Vortices shed alternately from the cylinder disappear and a region of zero-velocities is spread widely behind the cylinder. Shear layers between the stationary region and the uniform flow are thin and stable. Porous material does not absorb sound wave. These results suggest that porous material affects mainly the flow field around the bluff bodies and reduces aerodynamic noise by depriving momentum of the wake and suppressing unsteady motion of vortices.
一般社団法人日本機械学会の論文
2007-11-17