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Sound absorption of micro-perforated thin plates in a duct

덕트내 미세천공 박판의 흡음

  • 김현실 (한국기계연구원 음향소음팀) ;
  • 김봉기 (한국기계연구원 음향소음팀) ;
  • 김상렬 (한국기계연구원 음향소음팀) ;
  • 서윤호 (한국기계연구원 음향소음팀) ;
  • 마평식 (한국기계연구원 음향소음팀)
  • Received : 2017.08.07
  • Accepted : 2017.09.28
  • Published : 2017.09.30

Abstract

In this paper, sound absorption of thin elastic plates installed in a rigid duct is discussed using an analytic method. The number of plates can be one or two, and each plate might have micro-perforation. Vibration of the plates and sound pressure fields inside the duct and air cavity are expressed in terms of an infinite series of modal functions. Under the plane wave assumption, a low frequency approximation is derived by including the first few plate modes. It is found that the sound absorption coefficient of the plates without micro-perforation shows sharp peaks at resonance frequencies, and due to the interaction between the plates and air cavity, the resonance frequencies move as the cavity depth changes. For the case of micro-perforated plates, it is found that the sound absorption is mainly affected by the perforation ratio. When the perforation ratio is order of few percent, the sound absorption is almost independent of plate vibration.

Acknowledgement

Grant : 저주파흡/차음용 극한 물성 시스템융합기술 개발, 풍력발전시스템의 고장진단 및 예지보전기술 개발

Supported by : 한국기계연구원

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