Suppression of broadband noise radiated by a low-speed fan in a duct

The Journal of the Acoustical Society of America
Lixi HuangL G Feng

Abstract

Attenuation of ducted fan noise remains a technical challenge in the low frequency range as traditional duct lining becomes ineffective. This study proposes a reactive method to suppress the sound radiation from an axial-flow fan. The method is particularly effective in the low frequency region and covers a broad band. Its effect is derived from two mechanisms. One is the reduction in the confining effects of duct walls when the duct radius is increased; the other is the acoustic interference between the direct radiation from the fan and reflections by the duct junctions. This interference is always destructive for axial dipoles when the frequency approaches zero. This performance differs from normal passive control methods, which become totally ineffective toward zero frequency. An approximate plane-wave theory explains the essential physics of the method, and its quantitative prediction is found to agree well with a full numerical simulation using a spectral method of Chebyshev collocation. The latter is validated by experiment using an axial-flow fan in a duct of finite length. Broadband noise reduction is achieved while the flow speed is kept unchanged. Practical difficulties of implementation for a fan with high pressure i...Continue Reading

References

Jan 13, 2004·The Journal of the Acoustical Society of America·Lixi Huang
Mar 12, 2005·The Journal of the Acoustical Society of America·J WangL Cheng
Aug 1, 1968·Proceedings of the National Academy of Sciences of the United States of America·M Morse

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Citations

Sep 18, 2012·The Journal of the Acoustical Society of America·Y LiuL Cheng
Oct 15, 2013·The Journal of the Acoustical Society of America·Qipeng FengXiangbin Meng
Oct 18, 2014·The Journal of the Acoustical Society of America·Y LiuL Cheng
Feb 3, 2020·The Journal of the Acoustical Society of America·Jianzheng GaoWeikang Jiang

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