The mode interactions and the sound transmission loss across the expansion chambers with and without tapered sections are studied by the finite element method in the present investigation. Results from chambers with symmetrical inlet and outlet suggest lower sound power transmission loss at frequencies below that of the first symmetrical transverse chamber mode when the tapered section angle is reduced. Weak sound power transmission loss is also observed for this chamber type at frequency higher than that of the first symmetrical duct mode. Numerous high and low sound power transmission loss regions are observed between these two eigenfrequencies. Higher plane wave power transmission loss can be found at smaller tapered section angle only if one of the chamber endings is not tapered. Such chamber bears important industrial application.

Issue Section:
Technical Papers
Keywords:
vibrations, structural acoustics, acoustic wave transmission, acoustic intensity, cloud chambers, eigenvalues and eigenfunctions, finite element analysis
Topics:
Acoustics, Cloud chambers, Ducts, Symmetry (Physics), Waves, Excitation
1.
Munjal
,
M. L.
, 1987,
Acoustics of Ducts and Mufflers
,
Wiley
, New York.
2.
Selamet
,
A.
, and
Ji
,
Z. L.
, 1997, “
Acoustic Attenuation Performance of Circular Expansion Chambers With Extended Inlet/Outlet
,”
J. Sound Vib.
0022-460X,
223
(
2
), pp.
197
–
212
.
Crossref
Search ADS
 
3.
Cummings
,
A.
, and
Chang
,
I. J.
, 1998, “
Sound Attenuation of a Finite Length Dissipative Flow Duct Silencer With Internal Mean Flow in the Absorbent
,”
J. Sound Vib.
0022-460X,
127
(
1
), pp.
1
–
17
.
Crossref
Search ADS
 
4.
El-Sharkawy
,
A. I.
, and
Nayfeh
,
A. H.
, 1978, “
Effect of an Expansion Chamber on the Propagation of Sound in Circular Ducts
,”
J. Acoust. Soc. Am.
0001-4966,
63
(
3
), pp.
667
–
674
.
Crossref
Search ADS
 
5.
Young
,
I. J.
, and
Crocker
,
M. J.
, 1975, “
Prediction of Transmission Loss in Mufflers by the Finite-Element Method
,”
J. Acoust. Soc. Am.
0001-4966,
57
(
1
), pp.
144
–
148
.
Crossref
Search ADS
 
6.
Ji
,
Z.
,
Ma
,
Q.
, and
Zhang
,
Z.
, 1994, “
Application of the Boundary Element Method to Predicting Acoustic Performance of Expansion Chamber Mufflers With Mean Flow
,”
J. Sound Vib.
0022-460X,
173
(
1
), pp.
57
–
71
.
7.
Munjal
,
M. L.
, 1987, “
A Simple Numerical Method for Three-Dimensional Analysis of Simple Expansion Chamber Mufflers of Rectangular as Well as Circular Cross-Section With a Stationary Medium
,”
J. Sound Vib.
0022-460X,
116
(
1
), pp.
71
–
88
.
Crossref
Search ADS
 
8.
Kinsler
,
L. E.
, and
Frey
,
A. R.
, 1962,
Fundamentals of Acoustics
,
Wiley
, New York.
9.
Eriksson
,
L. J.
, 1980, “
Higher Order Mode Effects in Circular Ducts and Expansion Chambers
,”
J. Acoust. Soc. Am.
0001-4966,
68
(
2
), pp.
545
–
550
.
Crossref
Search ADS
 
10.
Sadamoto
,
A.
, and
Murakami
,
Y.
, 2002, “
Resonant Properties of Short Expansion Chambers in a Circular Duct: Including Extremely Short Cases and Asymmetric Mode Wave Incidence Cases
,”
J. Sound Vib.
0022-460X,
249
(
1
), pp.
165
–
187
.
Crossref
Search ADS
 
11.
Kristiansen
,
U. R.
, and
Johansen
,
T. F.
, 1986, “
A Finite Element Study on the Optimum Shape of Simple Reactive Expansion Chamber
,”
J. Sound Vib.
0022-460X,
105
(
2
), pp.
347
–
350
.
Crossref
Search ADS
 
12.
Easwaran
,
V.
, and
Munjal
,
M. L.
, 1992, “
Plane Wave Analysis of Conical and Exponential Pipes With Incompressible Mean Flow
,”
J. Sound Vib.
0022-460X,
152
(
1
), pp.
73
–
93
.
Crossref
Search ADS
 
13.
Tang
,
S. K.
, and
Lau
,
C. K.
, 2002, “
Sound Transmission Across a Smooth Non-Uniform Section in an Infinitely Long Duct
,”
J. Acoust. Soc. Am.
0001-4966,
112
(
6
), pp.
2602
–
2611
.
Crossref
Search ADS
PubMed
 
14.
Langemyr
,
L.
,
Nordmark
,
A.
,
Ringh
,
M.
,
Ruhe
,
A.
,
Oppelstrup
,
J.
, and
Dorobantu
,
M.
, 2004,
Partial Differential Equation Toolbox User Guide
,
The MathWorks Inc.
(available on-line at http:www.mathworks.comhttp:www.mathworks.com).
15.
George
,
L. P.
, 1991,
Automatic Mesh Generation—Application to Finite Element Methods
,
Wiley
, New York.
16.
Watson
,
G. N.
, 1944,
A Treatise on the Theory of Bessel Functions
,
Cambridge University Press
, Cambridge.
Copyright © 2007
 by American Society of Mechanical Engineers
You do not currently have access to this content.