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Minchie Chiu - One of the best experts on this subject based on the ideXlab platform.
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shape optimization of one chamber perforated Mufflers filled with wool using simulated annealing
Journal of Marine Science and Technology, 2013Co-Authors: Minchie ChiuAbstract:Research on dissipative and reactive Mufflers has been addressed. However, the acoustical performance -sound transmission loss (STL)- of Mufflers within a constrained space is often insufficient. In this paper, to improve the acoustical efficiency, a one-chamber perforated Muffler filled with sound absorbing wool optimized by using simulated annealing (SA) in conjunction with the numerical decoupling technique is presented. A numerical case in eliminating a broadband noise is also introduced. To verify the reliability of SA optimization, optimal noise abatements for the pure tone are exemplified. Before the SA operation can be carried out, the accuracy of the mathematical models has been checked using the experimental data. Results indicate that the maximal STL is precisely located at the desired target tone. Moreover, the STL can be improved when the ratio of the perforated tube’s length and the porosity of the perforated tube and the acoustical flowing resistance of the wool increase and the Mach number and the expansion ratio decrease. Consequently, a successful approach used for the optimal design of the one-chamber dissipative Mufflers within a constrained space has been demonstrated.
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The Optimal Design of Multi-Chamber Side Mufflers Equipped with Perforated Cross-Flow Tubes and Intruding Tubes using Simulated Annealing
Journal of Mechanics, 2011Co-Authors: Yingchun Chang, Minchie ChiuAbstract:Research on new techniques of side-inlet/outlet Mufflers equipped with internal non-perforated intruding tubes has been discussed in recent literature; however, the research work of multi-chamber sideinlet/outlet Mufflers in conjunction with cross-flow tubes and open-ended perforated intruding tubes which may efficiently increase the acoustical performance is rare. Therefore, the main purpose of this paper is not only to analyze the sound transmission loss ( STL ) of three kinds of side-inlet/outlet Mufflers (a three-chamber Muffler with cross-flow tubes, a five-chamber Muffler with cross-flow tubes and a nonperforated tube, and a five-chamber Muffler with cross-flow tubes and a perforated tube) but also to optimize their best design shape within a limited space. In this paper, both the generalized decoupling technique and plane wave theory in solving the coupled acoustical problem are used. A four-pole system matrix in evaluating the acoustic performance is also deduced in conjunction with a simulated algorithm ( SA ). A numerical case in finding the optimal STL of Mufflers, which is constrained within a basement with a side-inlet/outlet, at targeted tones has been introduced. Before the optimization is carried out, an accuracy check of the mathematical model is performed. Results reveal that the maximal STL is precisely located at the desired target tone. Moreover, it has been seen that Mufflers with more chambers will increase the acoustic performance for both pure tone and broadband noise. Additionally, the acoustical performance of Mufflers conjugated with perforated intruding tubes is superior to those equipped with non-perforated tubes. Consequently, the approach used for seeking the optimal design of the STL proposed in this study is indeed easy and quite effective.
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shape optimization of multi chamber Mufflers with plug inlet tube on a venting process by genetic algorithms
Applied Acoustics, 2010Co-Authors: Minchie ChiuAbstract:Recently, research on new techniques of single-chamber plug-inlet Mufflers has been amply addressed. However, research work on shape optimization of multi-chamber plug-inlet Mufflers along with work on maximal back pressure has been sorely neglected. Therefore, a numerical case for eliminating broadband steam blow-off noise using multi-chamber plug-inlet Mufflers in conjunction with a genetic algorithm (GA) as well as a numerical decoupling technique, all within a space-constrained pressure drop, is introduced in this paper. To verify the reliability of the GA optimization, optimal noise abatements for various pure tones on a one-chamber plug-inlet Muffler are examined. Of course, the accuracy of the mathematical model must be supported by experimental data. Subsequently, optimal results then indicate that the maximal sound transmission losses are indeed located at the desired target tones. Consequently, both pressure drop and acoustical performance will increase when the diameters (at inlet tubes and perforated holes), the perforated ratio, and the length of perforated tubes are decreased.
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numerical optimization of a three chamber Muffler hybridized with a side inlet and a perforated tube by sa method
2010Co-Authors: Minchie ChiuAbstract:Research on new techniques of multi-chamber Mufflers equipped with a side inlet and an internal non-perforated tube has been well addressed and developed; however, the research work of multi-chamber Mufflers in conjunction with side inlet and internal perforated tubes which may efficiently increase the acoustical performance is rare. Therefore, the main purpose of this paper is to not only analyze the sound transmission loss (STL) of three-chamber side Mufflers with a perforated tube but also to optimize their best design shape under a limited space. In this paper, both the generalized decoupling technique and plane wave theory in solving the coupled acoustical problem are used. The four-pole system matrix in evaluating the acoustic performance is also deduced in conjunction with a simulated algorithm (SA). To verify the liability of the SA technique, the noise minimization of muffles at a targeted frequency is exemplified first. To appreciate the acoustical performance of various multi-chamber Mufflers with/without inner perforated tube, three kinds of multi-chamber Mufflers ― a one-chamber side Muffler, a two-chamber side Muffler hybridized with a non-perforated tube, and a three-chamber side Muffler hybridized with a perforated tube are introduced and assessed. In eliminating the broadband exhausted noise emitted from an air compressor’s inlet. Before the SA operation can be carried out, the accuracies of the mathematical models have to be checked by experimental data. The result reveals a three-chamber side Muffler hybridized with a perforated tube exhibits an excellent acoustical ability beyond the other Mufflers. Consequently, the approach used seeking the optimal design of the STL proposed in this study is indeed easy, economical and quite effective.
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shape optimization of one chamber Mufflers with reverse flow ducts using a genetic algorithm
2010Co-Authors: Minchie ChiuAbstract:Shape optimization on Mufflers within a limited space 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 one-chamber 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 genetic algorithm (GA), a robust scheme used to search for the global optimum by imitating the genetic evolutionary process, 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 a reliability check on the GA method. Moreover, the accuracy check of the mathematical model is performed. The optimal result in eliminating broadband noise reveals that the one-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.
Ml Munjal - One of the best experts on this subject based on the ideXlab platform.
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Theory and Design of the Double-Tuned Coaxial and Flow-Reversal Mufflers: A New Perspective
Journal of The Institution of Engineers (India): Series C, 2020Co-Authors: Ml MunjalAbstract:Double-tuning an expansion chamber consists in extending the inlet–outlet pipes into the chamber by certain specific lengths so that the TL peaks due to the quarter-wave resonances of the annular cavities cancel or tune out the TL troughs due to the axial standing waves in the simple expansion chamber. The transfer matrix method is combined with the direct electroacoustic analogies in this paper to derive simple analytical expressions for the TL spectra of the double-tuned coaxial chamber (DTCAC) Muffler or the axial-inlet, axial-outlet Muffler, the double-tuned flow-reversal chamber (DTFRC) Muffler or the inlet–outlet same-end Muffler and the semi-tuned coaxial chamber (STCAC) or axial-inlet, axial-outlet Muffler. It has been shown that barring the rather inconsequential sharp narrow peaks, the underlying overarching wide-band TL curve corresponds to a hypothetical simple expansion chamber, the effective lengths and diameter of which for the DTCAC Muffler, DTFRC Muffler and STCAC Muffler have been tabulated at the end of this paper. This novel approach would simplify analysis and facilitate synthesis of Mufflers with more than one semi-tuned as well as double-tuned chambers. Finally, some guidelines for design of these tuned Mufflers for the HVAC systems have been given where it has been emphasized that physical lengths of the extended pipes would be different from the acoustic lengths to the extent of the end corrections.
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On development of rational design guidelines for large side-inlet side-outlet perforated element Mufflers
Noise Control Engineering Journal, 2018Co-Authors: Km Kumar, Ml MunjalAbstract:Logistics of an acoustic enclosure for a diesel generator (DG) set require mounting of the exhaust Muffler on the top of the enclosure with side inlet and side outlet. In this article, four different, yet somewhat similar, side-inlet side-outlet (SISO) perforated element Muffler configurations have been investigated. It has been shown that the 1-D plane wave analysis is adequate for the first few harmonics of the engine speed order that are of prime interest for Muffler designers. This simplified analysis throws light on the significant role of the resistive part of the perforate impedance and thence the bias flow Mach number. In particular, the effect of bias flow in raising the troughs is suitably exploited while limiting the overall backpressure of the Muffler. The 1-D plane wave analysis, however, becomes too approximate at higher frequencies, and for that reason, one has to rely on the 3-D FEA for evaluation of the overall four-pole parameters of the Muffler. A convergence study has been performed on one of the four configurations in order to arrive at an average mesh size that can capture the transmission loss (TL) values correctly up to 1000 Hz, and thereby economize on the RAM as well as the computational time for analysis of all four configurations. The backpressure for all the four Muffler configurations is kept approximately the same. Finally, some design guidelines for similar Mufflers are discussed. (c) 2018 Institute of Noise Control Engineering.
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On the crucial role of mean flow in the design of multiply-connected coaxial perforated element Mufflers
10.3397 1 3762, 2017Co-Authors: Km Kumar, Ml MunjalAbstract:Efficient Muffler design for automotive engine requires adequate overall insertion loss (IL) in dB(A), lower backpressure to ensure low brake specific fuel consumption (BSFC) of the engine, and a low Muffler volume to engine capacity ratio. In this study, the role of mean flow on the flow-acoustic performance of four different multiply-connected co-axial Mufflers (MCCA) is illustrated. The parametric studies on one of the configurations highlight the importance of the bias and grazing mean flow Mach number. The automotive engines operate over a wide range of engine speeds, which demands a wideband transmission loss (TL) and insertion loss rather than sharp peaks at certain frequencies. In the literature, a higher mean flow Mach number has been associated with more flow-noise as well as backpressure. However, in this study, it is shown that higher mean flow can be used to advantage in the MCCA Mufflers by making use of the in line flow-acoustic resistance which raises the TL curve over the entire frequency range. This article presents some design guidelines for the Mufflers with higher specific insertion loss (ratio of overall insertion loss (in dB(A)) to the Muffler to engine volume ratio) as well as a modest backpressure. (C) 2017 Institute of Noise Control Engineering
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on an integrated transfer matrix method for multiply connected Mufflers
Journal of Sound and Vibration, 2012Co-Authors: N K Vijayasree, Ml MunjalAbstract:The commercial automotive Mufflers are generally of a complicated shape with multiply connected parts and complex acoustic elements. The analysis of such complex Mufflers has always been a great challenge. In this paper, an Integrated Transfer Matrix method has been developed to analyze complex Mufflers. Integrated transfer matrix relates the state variables across the entire cross-section of the Muffler shell, as one moves along the axis of the Muffler, and can be partitioned appropriately in order to relate the state variables of different tubes constituting the cross-section. The paper presents a generalized one-dimensional (1-D) approach, using the transfer matrices of simple acoustic elements, which are available from the literature. The present approach is robust and flexible owing to its capability to construct an overall matrix of the Muffler with the transfer matrices of individual acoustic elements and boundary conditions, which can then be used to evaluate the transmission loss, insertion loss, etc. Results from the present approach have been validated through comparisons with the available experimental and three-dimensional finite element method (FEM) based results. The results show good agreement with both measurements and FEM analysis up to the cut-off frequency. (C) 2011 Elsevier Ltd. All rights reserved.
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transverse plane wave analysis of short elliptical end chamber and expansion chamber Mufflers
International Journal of Acoustics and Vibration, 2010Co-Authors: A Mimani, Ml MunjalAbstract:The flow-reversal end chambers are used quite often in commercial automotive Mufflers. The conventional axial plane-wave theory is not able to predict their acoustic performance because of the fact that the length of the end chambers is not enough for the evanescent three-dimensional modes generated at the junctions to decay sufficiently for frequencies below the cut-off frequency. Also, due to the large expansion ratio at the inlet, the first few higher- order modes get cut on even in the low-frequency regime. This necessitates a finite element or boundary element analysis, which is cumbersome and time-consuming. Therefore, an ingenious one-dimensional method has been developed. It models plane-wave propagation in the transverse direction between the incoming pipe and the return pipe, with the lateral-end cavities being modeled as variable-area quarter-wave resonators. Making use of this novel approach, the transfer matrices have been derived for elliptical and circular cross-section Mufflers, which enable these elements to be analyzed along with the rest of the Muffler elements by means of the transfer matrix-based Muffler program. Through a comparison with a full, three-dimensional analysis on commercial software, it is shown that the one-dimensional approach presented in this paper is able to predict the transmission loss quite accurately up to about 1000 Hz for typical automotive Mufflers.
Jin Woo Lee - One of the best experts on this subject based on the ideXlab platform.
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Methods for evaluating in-duct noise attenuation performance in a Muffler design problem
Journal of Sound and Vibration, 2020Co-Authors: Jong Kyeom Lee, Jin Woo LeeAbstract:Abstract In this study, methods for evaluating the noise attenuation performance of a Muffler in a Muffler design problem are investigated, and a proper evaluation method is suggested for actual noise reduction in a duct when an optimally designed Muffler is mounted on a duct. Mathematical expressions of the transmission loss, insertion loss, and level difference for a simple expansion chamber Muffler are developed from basic acoustic equations. The effects of the locations of the measurement points, tailpipe length, and impedance at the end of the duct on the noise attenuation performance calculated using the three evaluation methods are discussed. The TL and IL maximization problems formulated using topology optimization are solved for a Muffler unit, and the noise attenuation performances of the optimally designed Mufflers are compared when mounted on a duct. Another acoustical topology optimization problem, a partition volume minimization problem for a Muffler design, is formulated to reduce the in-duct broadband noise, and the noise attenuation performance of the optimal Muffler obtained using this formulation is experimentally validated. These research results will contribute to the development of a Muffler design method with high accuracy by reducing the discrepancy between the noise attenuation performances of a Muffler unit and a Muffler mounted on a duct.
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optimal topology of reactive Muffler achieving target transmission loss values design and experiment
Applied Acoustics, 2015Co-Authors: Jin Woo LeeAbstract:Abstract A topology-optimization-based Muffler design method for a reactive Muffler is proposed and experimentally validated. In a reactive Muffler design problem, rigid partitions should be located optimally inside the Muffler to improve its acoustical attenuation performance in the target frequency range. In an optimal-performance Muffler, the partition volume should be made as small as possible, and the transmission loss value in the target frequency range should be high enough for flow noise reduction in a duct. To this end, a partition-volume-minimization problem achieving target transmission loss values is formulated by using acoustical topology optimization. The formulated Muffler design problem is solved for several target frequencies, and the effect of the initial values of the design variables on the optimal topology is investigated. Numerical simulation results show that the proposed formulation requires a smaller volume of partition than the previous topology-optimization-based formulation. The calculated transmission loss curves of the optimal Mufflers agree well with the measured transmission loss curves of Mufflers made of acrylic.
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Topology Optimization of Suction Muffler for Noise Attenuation
2012Co-Authors: Jin Woo Lee, Dong Wook ChoiAbstract:A topology optimization method is developed to optimally design suction Mufflers in reciprocating compressors. Suction Mufflers should be designed for high noise reduction. The suction Mufflers are not easy to systematically design because their outer shape is so complicated and the center axes of the inlet/outlet do not coincide. Muffler researchers in industry have designed the internal configuration of suction Mufflers intuitively and experientially. However, since our proposed Muffler design method is not restricted to location of the inlet and outlet and to the outer shape of suction Muffler, it could be applied to suction Muffler design problems. A topology optimization problem is formulated for a finite element model simulating a suction Muffler for a reciprocating compressor. Transmission loss value at a target frequency is selected as an objective function and partition volume is constrained. Design variables change continuously from zero to one during optimization process. The material filling one element is an intermediate material between fluid and solid in each iterative calculation and become fluid or rigid body at a final converged stage depending on the value of design variables. Rigid body elements build up partitions or flow path to increase transmission loss. The proposed Muffler design method is applied to a suction Muffler, which has been introduced at an international conference.
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topology optimization of Muffler internal partitions for improving acoustical attenuation performance
International Journal for Numerical Methods in Engineering, 2009Co-Authors: Jin Woo Lee, Yoon Young KimAbstract:The internal partition configuration of an expansion chamber Muffler affects significantly its acoustical transmission characteristics, but the use of systematic optimization methods to Muffler design problems is rare. The main objective of this research is to maximize the transmission loss at target frequencies by optimizing partition layouts inside a Muffler chamber by formulating an acoustical topology optimization problem. The selected target frequencies include the deep frequencies of a nominal Muffler in order to see the critical effects of partition configurations on the acoustical transmission characteristics. The effects of partition volume constraint ratios are also investigated and physics behind the optimized layouts is investigated. Numerical results show that Mufflers with optimized partition layouts outperform nominal Mufflers considerably, but the shapes and locations of the optimized partitions should be much different from those of conventional partitions.
Yingchun Chang - One of the best experts on this subject based on the ideXlab platform.
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The Optimal Design of Multi-Chamber Side Mufflers Equipped with Perforated Cross-Flow Tubes and Intruding Tubes using Simulated Annealing
Journal of Mechanics, 2011Co-Authors: Yingchun Chang, Minchie ChiuAbstract:Research on new techniques of side-inlet/outlet Mufflers equipped with internal non-perforated intruding tubes has been discussed in recent literature; however, the research work of multi-chamber sideinlet/outlet Mufflers in conjunction with cross-flow tubes and open-ended perforated intruding tubes which may efficiently increase the acoustical performance is rare. Therefore, the main purpose of this paper is not only to analyze the sound transmission loss ( STL ) of three kinds of side-inlet/outlet Mufflers (a three-chamber Muffler with cross-flow tubes, a five-chamber Muffler with cross-flow tubes and a nonperforated tube, and a five-chamber Muffler with cross-flow tubes and a perforated tube) but also to optimize their best design shape within a limited space. In this paper, both the generalized decoupling technique and plane wave theory in solving the coupled acoustical problem are used. A four-pole system matrix in evaluating the acoustic performance is also deduced in conjunction with a simulated algorithm ( SA ). A numerical case in finding the optimal STL of Mufflers, which is constrained within a basement with a side-inlet/outlet, at targeted tones has been introduced. Before the optimization is carried out, an accuracy check of the mathematical model is performed. Results reveal that the maximal STL is precisely located at the desired target tone. Moreover, it has been seen that Mufflers with more chambers will increase the acoustic performance for both pure tone and broadband noise. Additionally, the acoustical performance of Mufflers conjugated with perforated intruding tubes is superior to those equipped with non-perforated tubes. Consequently, the approach used for seeking the optimal design of the STL proposed in this study is indeed easy and quite effective.
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shape optimization of one chamber perforated plug non plug Mufflers by simulated annealing method
International Journal for Numerical Methods in Engineering, 2008Co-Authors: Yingchun Chang, Minchie ChiuAbstract:To economically and efficiently lower the venting noise, the development of a high-quality Muffler with compact volume has become crucial in the modern industrial field. The research work of shape optimization of straight silencers in conjunction with plug/non-plug perforated ducts which may noticeably increase the acoustical performance is rarely addressed; therefore, the main purpose of this paper is not only to analyze the sound transmission loss (STL) of a one-chamber plug/non-plug perforated Muffler but also to optimize the best design shape under a limited space. In this paper, on the basis of plane wave theory, the four-pole system matrix in evaluating the acoustic performance is derived by using the decoupled numerical method. Moreover, a simulated annealing (SA) algorithm searching for the global optimum by imitating the softening process of metal has been adopted during the Muffler's optimization. To assure SA's correctness, the STL's maximization of one-chamber perforated plug Mufflers at a targeted frequency of 500 Hz is exemplified first. Furthermore, a numerical case in dealing with a broadband noise emitted from a fan by using one-chamber plug/non-plug Mufflers has been introduced and fully discussed. To achieve a better optimization in SA, various SA parameter sets of cooling rate and iteration parameter values were used. Before the SA operation can be carried out, the accuracy check of the mathematical models with respect to plug/non-plug perforated Mufflers has to be supported by experimental data. The optimal result in eliminating broadband noise reveals that the Muffler with a plug acoustical mechanism has a better noise reduction than that of a non-plug Muffler. Consequently, the approach used for the optimal design of the noise elimination proposed in this study is certainly easy, economical, and quite effective. Copyright © 2007 John Wiley & Sons, Ltd.
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shape optimization of multi chamber cross flow Mufflers by sa optimization
Journal of Sound and Vibration, 2008Co-Authors: Minchie Chiu, Yingchun ChangAbstract:Abstract It is essential when searching for an efficient acoustical mechanism to have an optimally shaped Muffler designed specially for the constrained space found in today's plants. Because the research work of optimally shaped straight silencers in conjunction with multi-chamber cross-flow perforated ducts is rarely addressed, this paper will not only analyze the sound transmission loss (STL) of three kinds of cross-flow perforated Mufflers but also will analyze the optimal design shape within a limited space. In this paper, the four-pole system matrix used in evaluating acoustic performance is derived by using the 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 adopted during shape optimization. To reassure SA's correctness, the STL's maximization of three kinds of muffles with respect to one-tone and dual-tone noise is exemplified. Furthermore, the optimization of Mufflers with respect to an octave-band fan noise by the simulated algorithm has been introduced and fully discussed. Before the SA operation can be carried out, an accuracy check of the mathematical model with respect to cross-flow perforated Mufflers has to be performed by Munjal's analytical data and experimental data. The optimal result in eliminating broadband noise reveals that the cross-flow perforated Muffler with more chambers is far superior at noise reduction than a Muffler with fewer chambers. Consequently, the approach used for the optimal design of noise elimination proposed in this study is certainly easy and efficient.
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shape optimization on double chamber Muffler with side inlet outlet under space constraint
2005Co-Authors: Yingchun Chang, Minchie Chiu, Longjyi Yeh, Gaungjer LaiAbstract:The accessory facility of noise abatement is often confined for the necessity of equipment’s maintenance and operation; therefore, how to ultimate the acoustic performance of Mufflers within a limited space becomes an essential issue. This paper proposes an optimal design of a Muffler with two expansion chambers (hybridized with inlet and outlet tubes) under maximal sound transmission loss (STL) considerations. A graphic analysis system together with the two powerful gradient techniques is also described in detail. A set of initial design data is primarily derived via computer graphic analysis on sensitivity. The shape optimization of a Muffler is then carried out using the successive algorithm of iteration techniques. The results are not only summarized but also compared with each other. In order to determine the accuracy of this study, the results are confirmed using the Kuhn-Tucker Condition. A numerical case illustrating the elimination of pure tone noise is also introduced. Results reveal that the sound transmission loss (STL) is maximized at the desired frequency. This study reinforces the quick and effective approach of an optimal design for double-chamber Mufflers under space.
Shiying Wang - One of the best experts on this subject based on the ideXlab platform.
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Investigation on structure parameters and performances of combined Muffler
2009 4th IEEE Conference on Industrial Electronics and Applications, 2009Co-Authors: Jie Zhang, Shiying WangAbstract:The Muffler combined with jet and impedance is designed to control exhaust noise of diesel electric generator. The relationship between performances and structure parameters of Mufflers are analyzed, the equations of noise reduction are derived, the factors of influencing Muffler performances are obtained, and the selecting rules of them are established. The experimental research for the acoustic and aerodynamic performances of Muffler proved the theoretical results in consistency with the experimental one. Furthermore, the experiments show that the resistance-loss is caused mainly by the partial resistance-loss in expansion chamber. The designed Muffler combined with jet and impedance has good acoustic and aerodynamic performances, its amount of noise reduction is 40 dB. The resistance-loss of the Muffler is smaller and less than 51Pa at velocity 8m/s of airflow. The proposed rules of structural parameter selection have their meaningful references for designing and improving Muffler in engineering application.