Analysis of higher‐order mode effects in the circular expansion chamber with mean flow

1985 ◽  
Vol 77 (4) ◽  
pp. 1377-1388 ◽  
Author(s):  
Jeong‐Guon Ih ◽  
Byung‐Ho Lee
Keyword(s):  
Higher Order ◽  
Order Mode ◽  
Mean Flow ◽  
Expansion Chamber ◽  
Mode Effects ◽  
Higher Order Mode

Multi-Modal Transient Excitation Effects in an Infinite, Parallel-Plate Wave Guide

1972 ◽  
Vol 50 (22) ◽  
pp. 2826-2835 ◽  
Author(s):  
D. G. Dudley ◽  
J. P. Quintenz
Keyword(s):  
Frequency Domain ◽  
Parallel Plate ◽  
Delta Function ◽  
Step Function ◽  
Higher Order ◽  
Wave Guide ◽  
Order Mode ◽  
Plate Wave ◽  
Mode Effects ◽  
Higher Order Mode

An analysis of higher-order mode effects in a parallel-plate wave guide is presented. Green's functions for the wave guide are derived in the frequency domain which can be inverted analytically to give the step function response for the TM modes and the delta function response for the TE modes. Plots of the responses are given for different excitation functions and the results are interpreted physically at various locations in the structure.

An Assessment of High-Order-Mode Analysis and Shape Optimization of Expansion Chamber Mufflers

2015 ◽  
Vol 39 (4) ◽  
pp. 489-499 ◽  
Author(s):  
Min-Chie Chiu ◽  
Ying-Chun Chang
Keyword(s):  
Plane Wave ◽  
Higher Order ◽  
Mode Analysis ◽  
Order Mode ◽  
Expansion Chamber ◽  
Acoustic Effect ◽  
Frequency Wave ◽  
Acoustic Performance ◽  
Higher Order Mode ◽  
Dimensional Wave

Abstract A substantial quantity of research on muffler design has been restricted to a low frequency range using the plane wave theory. Based on this theory, which is a one-dimensional wave, no higher order wave has been considered. This has resulted in underestimating acoustical performances at higher frequencies when doing muffler analysis via the plane wave model. To overcome the above drawbacks, researchers have assessed a three-dimensional wave propagating for a simple expansion chamber muffler. Therefore, the acoustic effect of a higher order wave (a high frequency wave) is considered here. Unfortunately, there has been scant research on expansion chamber mufflers equipped with baffle plates that enhance noise elimination using a higher-order-mode analysis. Also, space-constrained conditions of industrial muffler designs have never been properly addressed. So, in order to improve the acoustical performance of an expansion chamber muffler within a constrained space, the optimization of an expansion chamber muffler hybridized with multiple baffle plates will be assessed. In this paper, the acoustical model of the expansion chamber muffler will be established by assuming that it is a rigid rectangular tube driven by a piston along the tube wall. Using an eigenfunction (higher-order-mode analysis), a four-pole system matrix for evaluating acoustic performance (STL) is derived. To improve the acoustic performance of the expansion chamber muffler, three kinds of expansion chamber mufflers (KA-KC) with different acoustic mechanisms are introduced and optimized for a targeted tone using a genetic algorithm (GA). Before the optimization process is performed, the higher-order-mode mathematical models of three expansion chamber mufflers (A-C) with various allocations of inlets/outlets and various chambers are also confirmed for accuracy. Results reveal that the STL of the expansion chamber mufflers at the targeted tone has been largely improved and the acoustic performance of a reverse expansion chamber muffler is more efficient than that of a straight expansion chamber muffler. Moreover, the STL of the expansion chamber mufflers will increase as the number of the chambers that separate with baffles increases.

Analysis of inertance due to the higher order mode effects in a sudden area discontinuity

1995 ◽  
Vol 185 (3) ◽  
pp. 515-529 ◽  
Author(s):  
A.D. Sahasrabudhe ◽  
M.L. Munjal ◽  
S. Anantha Ramu
Keyword(s):  
Higher Order ◽  
Order Mode ◽  
Mode Effects ◽  
Higher Order Mode
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