Share

IIR document

Improved mufflers acoustic attenuation by use of porous materials.

Author(s) : LOPES L., LENZI A., BAARS E.

Summary

Porous materials are commonly used to dissipate acoustic energy in many industrial applications. The advantage of acoustical noise control materials compared with resonators and other noise control elements is the good performance over wide frequency ranges. Many machines and products generate high noise levels requiring high attenuation. The purpose of this work is to obtain increased acoustic attenuation in mufflers by using porous materials. A model of the sound propagation in rigid structure porous materials presented by Fahy (2003) was used in this work. In acoustic systems numerical models the dissipation can be considered by representing the boundary conditions as normal specific acoustic impedance. This was calculated from the theory which is based on measurements of three physical parameters: flow resistivity, porosity and structure factor. The analyses of all prototypes are based on a frequency response function given by the ratio of acoustic pressure measured at the outlet and inlet of the muffler. Although the restrictions presented in the theory of sound propagation in rigid porous materials and some uncertainties in the experimental tests, a comparison between numerical and experimental results showed good agreement.

Available documents

Format PDF

Pages: ICR07-B2-1603

Available

  • Public price

    20 €

  • Member price*

    Free

* Best rate depending on membership category (see the detailed benefits of individual and corporate memberships).

Details

  • Original title: Improved mufflers acoustic attenuation by use of porous materials.
  • Record ID : 2008-0121
  • Languages: English
  • Source: ICR 2007. Refrigeration Creates the Future. Proceedings of the 22nd IIR International Congress of Refrigeration.
  • Publication date: 2007/08/21

Links


See other articles from the proceedings (839)
See the conference proceedings

Indexing