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Research Papers

Genetic Algorithm Optimization on a Venting System With Three-Chamber Hybrid Mufflers Within a Constrained Back Pressure and Space

[+] Author and Article Information
Min-Chie Chiu

Department of Mechanical and Automation Engineering,  Chung Chou University of Science and Technology, Yuanlin, Changhua 51003, Taiwan, R.O.C.minchie.chiu@msa.hinet.net

J. Vib. Acoust 134(2), 021005 (Jan 18, 2012) (11 pages) doi:10.1115/1.4005220 History: Received November 09, 2010; Revised September 28, 2011; Published January 18, 2012; Online January 18, 2012

Recently, research on new techniques for dissipative mufflers in dealing with the higher frequencies has been addressed. However, the shape optimization of hybrid mufflers in reducing broadband noise within a constrained space as well as a pressure-drop limit which are both concerned with the necessity of operation and system venting in practical engineering work was rarely tackled. Therefore, this study will not only analyze the sound transmission loss (STL) of a space-constrained multichamber hybrid muffler but also optimize the best design shape under a specified pressure drop. In this paper, the generalized decoupling technique and plane wave theory used to solve the coupled acoustical problem of perforated mufflers with/without sound absorbing material are presented. The four-pole system matrix used to evaluate acoustic performance is also introduced in conjunction with a genetic algorithm (GA). A numerical case for eliminating a broadband venting noise emitted from a pressure relief valve using four kinds of hybrid mufflers is also introduced. To verify the reliability of the GA optimization, optimal noise abatement for a pure tone (1000 Hz) is exemplified. Before the GA operation can be carried out, the accuracy of the mathematical models need to be checked using the experimental data. The optimal result in eliminating broadband noise reveals that the overall noise reductions with respect to various mufflers under a maximal allowable pressure drop of 100 Pa can achieve 62.6, 54.8, 32.3 and 87.8 dB. Consequently, the approach used for the optimal design of the multichamber hybrid mufflers under space and back pressure constrained conditions is indeed easy and quite effective.

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Copyright © 2012 by American Society of Mechanical Engineers
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Figures

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Figure 1

The noise abatement on the constrained venting system

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Figure 2

The outlines of these mufflers as noise-reduction devices (mufflers A–D)

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Figure 3

The acoustical fields and the back pressures with respect to various hybrid mufflers (mufflers A–D)

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Figure 4

Performance of a single-chamber dissipative muffler without the mean flow (L = 0.2572 m; d1 = 0.049 m; d2 = 0.1644 m; η = 8.4%; dH = 0.00498 m; density = 100 kg/m3 ; M = 0) (experimental data is from Lee [17])

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Figure 5

The block diagram of the GA optimization within a back pressure constraint situation

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Figure 6

The STL curves with respect to various GA parameters at the targeted tone (1000 Hz) for muffler A (1: pm and pc varied at pop = 100, bit = 20, and gen = 500; 2: pop and bit and gen varied at pm = 0.05 and pc = 0.8)

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Figure 7

The best STL curves with respect to mufflers A–D at the targeted tone of 1000 Hz

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Figure 8

The comparison of the original SWL with respect to the best STL curves of mufflers A–D (broadband noise)

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Figure 9

The mechanism of a acoustical dissipative element filled with a sound-absorbing material

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