Prediction of the Performance of the Expansion Chamber in Air Ducts

Abstract

An expansion chamber is frequently used as an acoustics silencer for the control of duct-borne noise in ventilation systems. The flow of air and the effect of sound pressure may cause the vibration of the end plates of the expansion chamber and in turn will influence the performance (usually in terms of the transmission loss (TL)) of the expansion chamber. By combining the plate bending element and the plane stress element, BEM (for acoustics systems) and FEM (for the structure analysis) are applied to predict the performance of the expansion muffler. A method for calculating the TL for acoustics silencer using BEM-FEM coupled model is therefore presented, and an improved method based on the four-pole parameters used in the BEM is obtained.

Keywords

expansion chamber silencer performance transmission loss

References

Bilawchuk

Fyfe

K.R.

, Comparison and implementation of the various numerical methods used for calculating transmission loss in silencer systems, Applied Acoustics, 64 (2003), pp. 903–916

Yeh

Long-Jyi

Chang

Ying-Chun

Chiu

Min-Chie

Lai

Gaung-Jer

, GA optimization on multi-segments muffler under space constraints, Applied Acoustics, 65 (2004), pp. 521–543

Cummings

, Low Frequency Acoustic Transmission through the Walls of Rectangular Ducts, Journal of Sound and Vibration, 1978, Vol. 61, No. 3, pp. 327–345

Cummings

, End Plate Vibration in Exhaust Silencer Chambers, Journal of Sound and Vibration, 1973, Vol. 30, No. 3, pp. 367–372

Young

Crocker

. Finite Element Acoustical Analysis of Complex Muffler Systems With and Without Wall Vibration. Noise Control Engineering, 1977, Vol. 9, No. 2, pp. 86–93

Lou

T.W.

Cheng

C.Y.R.

, Boundary element analysis of packed silencers with a substructuring technique, Engineering Analysis with Boundary Elements, 27 (2003), pp. 643–653

Barbieri

de Lima

Fonseca K.

, Application of the Galerkin-FEM and the improved four-pole parameter method to predict acoustic performance of expansion chambers, Journal of Sound and Vibration, In Press (2004)

Mourand

K.M.

. The Application of the Boundary Element Method to Predict the Response of a differential Operator Model for a Coupled Visco Elastic-Acoustic System. Ph.D. Thesis, North Carolina State University, 1990

J. Y.

, Finite Element Method (Chinese). Beijing: Beijing University of Posts and Telecommunication Press, 1998

10.

Tsuji

Tsuchiya

Kagawa

, Finite Element and Boundary Element Modeling for the Acoustic Wave Transmission in Mean Flow Medium, Journal of Sound and Vibration, 2002, Vol. 255, No. 5, pp. 849–866

11.

Long

Z. F.

Cen

, Theory of Finite Element Method: Principle, Program, Progress (Chinese). Beijing: China Water-Power Press, 2001

12.

Munjal

M. L.

, Acoustics of Ducts and Mufflers. New York: Wiley-Inter science, 1987

13.

Lee

C.M.

Royster

L.H.

Ciskowski

R.D.

, Coupling of FEM and BEM for the Analysis of a Structure-Acoustic-Cavity System. Boundary Elements XV. Southampton: computational Mechanics Publications, 1993

14.

Blevins

R.D.

. Formulas for Natural Frequency and Mode Shape. Van nostrand Reinhold Co., 1979

15.

Dowling

John F.

Peat

Keith S.

, An algorithm for the efficient acoustic analysis of silencers of any general geometry, Applied Acoustics, 65 (2004), pp. 211–227

16.

Cummings

Astley

R.J.

. Finite Element Computation of Attenuation in Bar-silencer and Comparison with Measured data. Journal of Sound and Vibration, 1996, Vol. 196, No. 3, pp. 351–369