Among the various descriptors of a multi-cylinder engine exhaust muffler system performance, it is evident that insertion loss and radiated sound pressure are the most useful. Insertion loss depicts the effectiveness of a muffler, whereas radiated sound pressure level is the design criterion used to meet the noise regulations. The main difficulty in prediction of these descriptors is the characterization of the source. In addition, both flow and temperature gradient effects have to be included in the modeling. This paper describes a theoretical acoustical model to predict insertion loss and radiated sound pressure level, in which the source impedance is obtained from measurement (see the accompanying paper) and from which the source strength is estimated. Also, both flow and temperature gradient effects are included in the analysis. The implications due to the various assumptions for the source impedance in the modeling have been investigated. The studies are carried out on two exhaust system configurations. Good agreement is obtained provided the measured impedance is used and also if mean flow and temperature gradients effects are included in the theoretical model. See also TRIS 382998. (Author/TRRL)

  • Availability:
  • Corporate Authors:

    Academic Press Incorporated

    24-28 Oval Road
    London NW1 7DX,   England 
  • Authors:
    • Prasad, M G
    • Crocker, M J
  • Publication Date: 1983-10

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00382999
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD, TRIS
  • Created Date: May 30 1984 12:00AM