1512 ドアミラーから放射される空力音響フィードバック音の動的低減技術の開発(J11-2 流れと音の相関計測,J11 流体関連の騒音と振動)

概要

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The aim of this investigation is to develop the aerodynamic noise reduction technique for automobiles with active control. To reduce the tonal noise from a rear-view mirror, oscillating jets were impinging into the boundary layer of the rear-view mirror. Since the aerodynamic tonal noise of rearview mirror was generated by a small perturbation caused by a small step on a surface of the rearview mirror, oscillating jets were destroyed the seed of the noise. The experimental results showed that the noise reduction level depended on the frequency and intensity of the oscillating jets. The tonal noise level of the rear-view-mirror with the active control was 20dB smaller than that of the conventional rear-view mirror. The average velocity of the impinging jet was only 0.3% of that of the uniform flow. It revealed that the oscillating jets effectively reduced aerodynamic noise with small amount of energy.
一般社団法人日本機械学会の論文
2007-09-07