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Minchie Chiu - One of the best experts on this subject based on the ideXlab platform.

  • numerical analysis of circular straight Mufflers equipped with three chambers at high order modes
    Applied Acoustics, 2019
    Co-Authors: Yingchun Chang, Minchie Chiu, Shiuanen Huang
    Abstract:

    Abstract Plane wave theory has been used in predicting the acoustical performance of one-chamber straight Mufflers. But, the acoustical effect of the Mufflers at higher frequencies that are beyond the threshold of the cut-off frequency has been neglected. In addition, there is a need for a more compact muffler design for use inside a space-constrained working area. In order to improve the acoustical performance of straight Mufflers, a space-constrained multi-chamber muffler using a more accurate predicting model in conjunction with an optimizer is proposed. In this paper, an eigen function that uses a three dimensional wave propagation to deduce the acoustical field as a four-pole matrix form is applied. An overall four-pole system matrix that multiplies individual matrices is adopted in evaluating the Transmission Loss (TL) for the hybrid Mufflers. A circular and three-chamber straight muffler is introduced and optimized for various targeted tones using both Genetic Algorithm (GA) and Simulated Annealing (SA) Methods in conjunction with five objective functions (case A–case E). Before the optimization process is carried out, an accuracy check of the mathematical models for the circular one-chamber muffler is carried out. In order to verify the reliability of the GA and SA methods, a single-objective optimization of the three-chamber straight muffler at a targeted tone of 2000 Hz using GA method and SA method has been executed. Results reveal that the TL can be maximized at the targeted frequency when using either the GA method or the SA method. In addition, the noise reduction will increase if the number of chambers increases. Moreover, the acoustical performance of the Mufflers will be reversely proportional to the diameter of the inlet/outlet tubes. Consequently, results reveal that the TL of the circular hybrid Mufflers at targeted frequencies can be simultaneously improved by using the fourth and fifth strategies of objective functions in which the inverse of the summation summing up the individual target frequency’s deviation square between the targeted transmission loss and the predicted transmission loss has been built.

  • shape optimization of Mufflers composed of multiple rectangular fin shaped chambers using differential evolution method
    Archives of Acoustics, 2015
    Co-Authors: Minchie Chiu, Yingchun Chang, Hochih Cheng, Weiting Tai
    Abstract:

    There has been considerable research done on multi-chamber Mufflers used in the elimination of industrial venting noise. However, most research has been restricted to lower frequencies using the plane wave theory. This has led to underestimating acoustical performances at higher frequencies. Additionally, because of the space-constrained problem in most plants, the need for optimization of a compact muffler seems obvious. Therefore, a muffler composed of multiple rectangular fin-shaped chambers is proposed. Based on the eigenfunction theory, a four-pole matrix used to evaluate the acoustic performance of Mufflers will be deduced. A numerical case for eliminating pure tones using a three-fin-chamber muffler will also be examined. To delineate the best acoustical performance of a space-constrained muffler, a numerical assessment using the Differential Evolution (DE) method is adopted. Before the DE operation for pure tone elimination can be carried out, the accuracy of the mathematical model must be checked using experimental data. The results reveal that the broadband noise has been efficiently reduced using the three-fin-chamber muffler. Consequently, a successful approach in eliminating a pure tone using optimally shaped three-fin-chamber Mufflers and a differential evolution method within a constrained space has been demonstrated.

  • numerical assessment for a broadband and tuned noise using hybrid Mufflers and a simulated annealing method
    Journal of Sound and Vibration, 2013
    Co-Authors: Minchie Chiu
    Abstract:

    Abstract A broadband noise hybridized with pure tones often occurs in practical engineering work. However, assessments of a muffler's optimal shape design that would simultaneously overcome a broadband noise hybridized with multiple tones within a constrained space were rarely addressed. In order to promote the best acoustical performance in Mufflers, five kinds of the hybrid Mufflers composed of a reactive unit, a dissipative unit, and Helmholtz resonator (HR) units will be proposed. Moreover, to strengthen the noise elimination at the pure tone, Mufflers having parallel multiple-sectioned HRs or having multiple HR connections in series (muffler D and muffler E) will be also presented in the noise abatement. On the basis of the plane wave theory, the four-pole system matrix used to evaluate the acoustic performance of a multi-tone hybrid Helmholtz muffler will be presented. A numerical case for eliminating broadband noise hybridized with a pure tone emitted from a machine room using five kinds of Mufflers (muffler A–E) will also be introduced. To find the best acoustical performance of a space-constrained muffler, a numerical assessment using a simulated annealing (SA) method is adopted. To verify the availability of the SA optimization, a numerical optimization of muffler A at a pure tone (280 Hz) is exemplified. Before the SA operation can be carried out, the accuracy of the mathematical model will be checked using the experimental data. The influences of the sound transmission loss (STL) with respect to N 1 -array HR and the STL with respect to one-array HR sectioned in N 2 divisions have also been assessed. Also, the influence of the STL with respect to the design parameters such as the ratio of d 1 / d 2 , the diameter of the perforated hole (dH), the porosity ( p %) of the perforated plate, and the outer diameter ( d 2 ) of the dissipative unit has been analyzed. Consequently, a successful approach in eliminating a broadband noise hybridized with a pure tone using optimally shaped hybrid Mufflers and a simulated annealing method within a constrained space has been demonstrated.

  • noise elimination of a multi tone broadband noise with hybrid helmholtz Mufflers using a simulated annealing method
    Archives of Acoustics, 2012
    Co-Authors: Minchie Chiu
    Abstract:

    Noise control is essential in an enclosed machine room where the noise level has to comply with the occupational safety and health act. In order to overcome a pure tone noise with a high peak value that is harmful to human hearing, a traditional reactive muffler has been used. However, the traditional method for designing a reactive muffler has proven to be time-consuming and insufficient. In order to efficiently reduce the peak noise level, interest in shape optimization of a Helmholtz muffler is coming to the forefront. Helmholtz Mufflers that deal with a pure tone have been adequately researched. However, the shape optimization of multi-chamber Helmholtz Mufflers that deal with a broadband noise hybridized with multiple tones within a constrained space has been mostly ignored. Therefore, this study analyzes the sound transmission loss (STL) and the best optimized design for a hybrid Helmholtz muffler under a space- constrained situation. On the basis of the plane wave theory, the four-pole system matrix used to evaluate the acoustic performance of a multi-tone hybrid Helmholtz muffler is presented. Two numerical cases for eliminating one/two tone noises emitted from a machine room using six kinds of Mufflers (muffler AF) is also introduced. To find the best acoustical performance of a space-constrained muffler, a numerical assessment using a simulated annealing (SA) method is adopted. Before the SA operation can be carried out, the accuracy of the mathematical model has been checked using the experimental data. Eliminating a broadband noise hybridized with a pure tone (130 Hz) in Case I reveals that muffler C composed of a one- chamber Helmholtz Resonator and a one-chamber dissipative element has a noise reduction of 54.9 (dB). Moreover, as indicated in Case II, muffler F, a two-chamber Helmholtz Resonator and a one-chamber dissipative element, has a noise reduction of 69.7 (dB). Obviously, the peak values of the pure tones in Case I and Case II are efficiently reduced after the muffler is added. Consequently, a successful approach in eliminating a broadband noise hybridized with multiple tones using optimally shaped hybrid Helmholtz Mufflers and a simulated annealing method within a constrained space is demonstrated.

  • numerical assessment of hybrid Mufflers on a venting system within a limited back pressure and space using simulated annealing
    Journal of Low Frequency Noise Vibration and Active Control, 2011
    Co-Authors: Minchie Chiu
    Abstract:

    Although research in finding optimal muffler shapes for low-frequencies noise using reactive Mufflers has already been addressed, research into shape optimization of hybrid Mufflers that reduce broadband noise within a constrained pressure-drop backpressure is lacking. Therefore, the shape optimization of four kinds of hybrid Mufflers using simulated annealing (SA) in conjunction with the generalized decoupling technique and plane wave theory are presented. Here, a numerical case in eliminating nitrogen venting noise is introduced. The reliability of the SA optimization is also verified using the optimization of muffler A for a pure tone. Moreover, the accuracy of the mathematical models is acceptable with minor deviations between the theoretical and experimental data. Results reveal that the higher backpressure limit will result in a higher acoustical performance. Consequently, the acoustical performance for a hybrid muffler equipped with multiple reactive chambers and one dissipative chamber is superior to that of reactive Mufflers.

Yingchun Chang - One of the best experts on this subject based on the ideXlab platform.

  • numerical analysis of circular straight Mufflers equipped with three chambers at high order modes
    Applied Acoustics, 2019
    Co-Authors: Yingchun Chang, Minchie Chiu, Shiuanen Huang
    Abstract:

    Abstract Plane wave theory has been used in predicting the acoustical performance of one-chamber straight Mufflers. But, the acoustical effect of the Mufflers at higher frequencies that are beyond the threshold of the cut-off frequency has been neglected. In addition, there is a need for a more compact muffler design for use inside a space-constrained working area. In order to improve the acoustical performance of straight Mufflers, a space-constrained multi-chamber muffler using a more accurate predicting model in conjunction with an optimizer is proposed. In this paper, an eigen function that uses a three dimensional wave propagation to deduce the acoustical field as a four-pole matrix form is applied. An overall four-pole system matrix that multiplies individual matrices is adopted in evaluating the Transmission Loss (TL) for the hybrid Mufflers. A circular and three-chamber straight muffler is introduced and optimized for various targeted tones using both Genetic Algorithm (GA) and Simulated Annealing (SA) Methods in conjunction with five objective functions (case A–case E). Before the optimization process is carried out, an accuracy check of the mathematical models for the circular one-chamber muffler is carried out. In order to verify the reliability of the GA and SA methods, a single-objective optimization of the three-chamber straight muffler at a targeted tone of 2000 Hz using GA method and SA method has been executed. Results reveal that the TL can be maximized at the targeted frequency when using either the GA method or the SA method. In addition, the noise reduction will increase if the number of chambers increases. Moreover, the acoustical performance of the Mufflers will be reversely proportional to the diameter of the inlet/outlet tubes. Consequently, results reveal that the TL of the circular hybrid Mufflers at targeted frequencies can be simultaneously improved by using the fourth and fifth strategies of objective functions in which the inverse of the summation summing up the individual target frequency’s deviation square between the targeted transmission loss and the predicted transmission loss has been built.

  • shape optimization of Mufflers composed of multiple rectangular fin shaped chambers using differential evolution method
    Archives of Acoustics, 2015
    Co-Authors: Minchie Chiu, Yingchun Chang, Hochih Cheng, Weiting Tai
    Abstract:

    There has been considerable research done on multi-chamber Mufflers used in the elimination of industrial venting noise. However, most research has been restricted to lower frequencies using the plane wave theory. This has led to underestimating acoustical performances at higher frequencies. Additionally, because of the space-constrained problem in most plants, the need for optimization of a compact muffler seems obvious. Therefore, a muffler composed of multiple rectangular fin-shaped chambers is proposed. Based on the eigenfunction theory, a four-pole matrix used to evaluate the acoustic performance of Mufflers will be deduced. A numerical case for eliminating pure tones using a three-fin-chamber muffler will also be examined. To delineate the best acoustical performance of a space-constrained muffler, a numerical assessment using the Differential Evolution (DE) method is adopted. Before the DE operation for pure tone elimination can be carried out, the accuracy of the mathematical model must be checked using experimental data. The results reveal that the broadband noise has been efficiently reduced using the three-fin-chamber muffler. Consequently, a successful approach in eliminating a pure tone using optimally shaped three-fin-chamber Mufflers and a differential evolution method within a constrained space has been demonstrated.

  • The Optimal Design of Multi-Chamber Side Mufflers Equipped with Perforated Cross-Flow Tubes and Intruding Tubes using Simulated Annealing
    Journal of Mechanics, 2011
    Co-Authors: Yingchun Chang, Minchie Chiu
    Abstract:

    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.

  • shape optimization of one chamber perforated plug non plug Mufflers by simulated annealing method
    International Journal for Numerical Methods in Engineering, 2008
    Co-Authors: Yingchun Chang, Minchie Chiu
    Abstract:

    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.

  • shape optimization of multi chamber cross flow Mufflers by sa optimization
    Journal of Sound and Vibration, 2008
    Co-Authors: Minchie Chiu, Yingchun Chang
    Abstract:

    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.

Jin Woo Lee - One of the best experts on this subject based on the ideXlab platform.

  • Methods for evaluating in-duct noise attenuation performance in a muffler design problem
    Journal of Sound and Vibration, 2020
    Co-Authors: Jong Kyeom Lee, Jin Woo Lee
    Abstract:

    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.

  • optimal topology of reactive muffler achieving target transmission loss values design and experiment
    Applied Acoustics, 2015
    Co-Authors: Jin Woo Lee
    Abstract:

    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.

  • Topology Optimization of Suction Muffler for Noise Attenuation
    2012
    Co-Authors: Jin Woo Lee, Dong Wook Choi
    Abstract:

    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.

  • topology optimization of muffler internal partitions for improving acoustical attenuation performance
    International Journal for Numerical Methods in Engineering, 2009
    Co-Authors: Jin Woo Lee, Yoon Young Kim
    Abstract:

    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.

Chao-nan Wang - One of the best experts on this subject based on the ideXlab platform.

  • flow induced aerodynamic noise analysis of perforated tube Mufflers
    Journal of Mechanics, 2013
    Co-Authors: Chao-nan Wang, Chuancheung Tse, S C Chen
    Abstract:

    Despite the analysis of muffler performance for many years, most works focus mainly on reducing inlet sound and fail to consider the flow effect. Most of their results correlate well with the experimental measurements. Subsequent works have considered the mean flow effect. Owing to Doppler's effect, transmission loss curve of the muffler will shift in its corresponding frequency. However, the correlation is worse than the experimental results since the flow induced noise does not include in the analysis. This work elucidates how flow induced noise affects muffler performance by analyzing a uniform flow that passes through perforated Mufflers. The flow field is calculated with the CFD method, followed by evaluation of the aerodynamic noise based on the simulation results. Additionally, the procedure is simplified by computing and comparing only the total sound power induced by the flow in the muffler interior. Two muffler types, Helmholtz resonator and plug perforated tube muffler, are analyzed and discussed.

  • ATTENUATION FOR THE SIMPLE EXPANSION CHAMBER MUFFLER WITH A RIGHT ANGLE INLET
    Journal of Mechanics, 2011
    Co-Authors: Chao-nan Wang
    Abstract:

    The simple expansion chamber muffler is a base control device whose use is to attenuate sound power, and has been known for a long time. Some of the most compelling research has focused on the Mufflers with a straight inlet and outlet. To date, a muffler with a right angle inlet has never been studied. Therefore, the purpose of this work is to analyze the simple expansion chamber muffler with a right angle inlet. The numerical results show a comparable agreement between the experiment and other numerical approaches. A discussion is also presented in this work on the muffler with a different radius to that of the inlet/outlet pipe, a different inlet part, etc . The result clearly shows that the attenuation of the muffler with a right angle inlet is better than that with a straight inlet at particular frequencies. In addition, the Mufflers do not have any absorbent linings attached to the inside of them, unlike the right angle-inlets which do. However, the propagation of sound in the muffler with a right angle inlet can lead its sound power to be attenuated about 10 ∼ 40dB at those particular frequencies.

  • The application of boundary element evaluation on a silencer in the presence of a linear temperature gradient
    Applied Acoustics, 2001
    Co-Authors: Chao-nan Wang, Yih-nan Chen, Jean-yih Tsai
    Abstract:

    Abstract A boundary element method for analyzing the acoustic performance of a muffler in the presence of a linear temperature gradient is developed. In order to simulate the temperature gradient, the muffler is divided into segments with different constant temperatures. The boundary element approach is applied to each sub-volume to establish the relationship between pressure and its gradient on the surface. Then combining all the sub-volumes by matching the continuity of pressure and velocity on the contact surface to obtain the relationship of the inlet and outlet of a muffler Consequently, the transmission loss of a muffler can be evaluated. In the present study, the performance of Mufflers with different temperature and temperature gradients is investigated.

Chuan Huang - One of the best experts on this subject based on the ideXlab platform.

  • Numerical optimization of flow noises for Mufflers based on the improved BP neural network
    JVE International, 2016
    Co-Authors: Xiao-lin Xie, Feng Gao, Xiao-yun Huang, Chuan Huang
    Abstract:

    Aimed at the large noise of tail pipe, the method of fluid dynamics was firstly applied to analyze the inner flow field of the exhaust muffler. According to the result, the large noise of tail pipe was mainly caused by air flow regeneration noise, and the vice muffler was not the major component for generating airflow noise. The largest pressure of the whole muffler system was at the outlet end of main Mufflers. The largest flow velocity was in the connection pipe between main Mufflers and vice Mufflers. Secondly, boundary element model of transmission loss for the muffler was established to compare and analyze it with the experimental. The experimental and computational value of transmission loss for the muffler has a good consistency in both change trend and numerical value, and the computational model was reliable. Finally, GA-BP neural network algorithm was used to optimize the acoustic performance of the muffler. Airflow noises of the tail pipe were effectively reduced through optimizing the inner structure of the muffler