AM05-23-011 ドアミラーから放出される空力的な異音の発生条件の検討(騒音3,一般講演)

概要

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The Purpose of this investigation to understand mechanism of aerodynamic noise from rear view mirrors. In order to clarify velocity fluctuation and radiated noise, velocity fluctuation and aerodynamic sound were measured in the low-noise wind tunnel. The fundamental flow around rear view mirrors was simulated with half cylindrical model which was proposed by German researchers. The pure tone was observed in the case of bump with rear view mirror. The instability wave was introduced in the approaching boundary layer by the small bump. The sinusoidal wave was observed both of energy and sound spectra. The coherence function in terms of velocity fluctuation and noise was high level from the bump to edge of mirror. On the other hand, no correlation was observed in the wake of rear view mirror. The noise was not generated when the approaching boundary layer was turbulence. Therefore, laminar boundary layers and sinusoidal waves were dominant noise source of rear view mirror. It reveals that The bump on the rear view mirror surface is extremely important to generate aerodynamic noise from a rear view mirror.
日本流体力学会の論文
2005-09-05