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Optimization Design of Hybrid Mufflers on Broadband Frequencies Using the Genetic Algorithm

Chiu M-C.

Archives of Acoustics

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2011

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Vol. 36, No. 4

795-822

EN

Recently, there has been research on high frequency dissipative mufflers. However, research on shape optimization of hybrid mufflers that reduce broadband noise within a constrained space is sparse. In this paper, a hybrid muffler composed of a dissipative muffler and a reactive muffler within a constrained space is assessed. Using the eigenvalues and eigenfunctions, a coupling wave equation for the perforated dissipative chamber is simplified into a four-pole matrix form. To efficiently find the optimal shape within a constrained space, a four-pole matrix system used to evaluate the acoustical performance of the sound transmission loss (STL) is eval- uated using a genetic algorithm (GA). A numerical case for eliminating a broadband venting noise is also introduced. To verify the reliability of a GA optimization, optimal noise abatements for two pure tones (500 Hz and 800 Hz) are exemplified. Before the GA operation can be carried out, the accuracy of the mathematical models has been checked using experimental data. Results indicate that the maximal STL is precisely located at the desired target tone. The optimal result of case studies for eliminating broadband noise also reveals that the overall sound power level (SWL) of the hybrid muffler can be reduced from 138.9 dB(A) to 84.5 dB(A), which is superior to other mufflers (a one-chamber dissipative and a one-chamber reactive muffler). Consequently, a successful approach used for the optimal design of the hybrid mufflers within a constrained space has been demonstrated.

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Optimization of Multi-Chamber Mufflers with Reverse-Flow Ducts by Algorithm of Simulated Annealing

Chang Y-C., Chiu M-C.

Archives of Acoustics

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2010

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Vol. 35, No. 1

13-33

EN

Shape optimization on mufflers within a limited space volume is essential for industry, where the equipment layout is occasionally tight and the available space for a muffler is limited for maintenance and operation purposes. To proficiently enhance the acoustical performance within a constrained space, the selection of an appropriate acoustical mechanism and optimizer becomes crucial. A multi-chamber side muffler hybridized with reverse-flow ducts which can visibly increase the acoustical performance is rarely addressed; therefore, the main purpose of this paper is to numerically analyze and maximize the acoustical performance of this muffler within a limited space. In this paper, the four-pole system matrix for evaluating the acoustic performance – sound transmission loss (STL) – is derived by using a decoupled numerical method. Moreover, a simulated annealing (SA) algorithm, a robust scheme in searching for the global optimum by imitating the softening process of metal, has been used during the optimization process. Before dealing with a broadband noise, the STL’s maximization with respect to a one-tone noise is introduced for the reliability check on the SA method. Moreover, the accuracy check of the mathematical models with respect to various acoustical elements is performed. The optimal result in eliminating broadband noise reveals that the multi-chamber muffler with reverse-flow perforated ducts is excellent for noise reduction. Consequently, the approach used for the optimal design of the noise elimination proposed in this study is easy and effective.

3

Simulated annealing optimization on multi-chamber mufflers hybridized with perforated plug-inlet under space constraints

Chiu M. C.

Archives of Acoustics

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2009

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Vol. 34, No. 3

305-343

EN

Because of the precious space in modern industry, a prerequisite in optimizing the acoustical performance of mufflers within a compact volume is necessary. To depress the acoustical performance, a multi-chamber muffler hybridized with perforated plug-inlet tubes which may dramatically increase the acoustical performance, is then adopted and optimized under space constraint. In this paper, both the numerical decoupling technique and simulated annealing (SA) a˙lgorithm for solving the coupled acoustical problem of perforated plug-inlet tubes and optimizing the muffler shape are used. To appreciate the acoustical ability of the new mufflers, traditional multi-chamber mufflers with extended inlet tubes have been assessed. Furthermore, noise reductions in broadband and pure tones noise are also introduced. But before the SA operation can be carried out, the accuracy of the mathematical model has to be checked by experimental data. Results reveal that the maximal STL is precisely located at the desired target tone. In addition, the acoustical performance of mufflers conjugated with perforated plug-inlet tubes is superior to that hybridized with extended inlet tubes. Moreover, the more chambers the mufflers have, the higher acoustical performance they will reach. Consequently, we demonstrate a successful SA application to the muffler design.

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GA optimization on single-chamber muffler hybridized with extended tube under space constraints

Chang Y. C., Yeh L. J., Chiu M. C.

Archives of Acoustics

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2004

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Vol. 29, no. 4

577-596

EN

Mufflers are habitually adopted in gas venting systems under space constraint for maintenance and operation. The shape optimization in the muffler to maximize the sound performance is then highly focused, accordingly. In this paper, the shape design of a muffler with extended tubes optimized by the genetic algorithm (GA) is presented. A numerical case in eliminating the pure tone noise is introduced. Before optimization, the mathematical model is compared by the experimental data for an accuracy check. The results indicate that the sound transmission loss (STL) is maximized exactly at the designed frequency. Consequently, we demonstrate a successful GA application on the muffler design.