Additive manufacturing allows the fabrication of acoustical materials with previously unrealizable micro- and macrostructural complexities. However, the still nascent understanding of various geometrical defects occurring during the additive process remains a barrier to accurately predicting the acoustical behavior of such complex absorbers. In this study, we present the results from our efforts on numerically modeling the absorption behavior of periodic porous absorbers fabricated using the stereolithography (SLA) technique using the hybrid micro-macro multiphysics approach. Specifically, we focus on understanding the role played by the expansion or shrinkage of the solid ligaments during the SLA process on the acoustical properties of the final printed samples. First, the periodic absorbers are modeled using COMSOL multiphysics, where the transport properties are derived using the micro-modeling method and sound absorption behavior using the Johnson-Champoux-Allard-Lafarge-Pride semi-empirical model. Then, results from the expansion study guide the changes in the ligament sizes in the unit cell modeling. Finally, the fabricated samples are tested using an impedance tube, and the measured absorption properties are compared to the a priori numerical predictions. Results indicate that accounting for fabrication defects within the numerical modeling schema can provide reliable sound absorption predictions for additively manufactured porous absorbers.
{"title":"Effect of geometrical defects on the acoustical transport properties of periodic porous absorbers manufactured using stereolithography","authors":"Amulya Lomte, Bhisham Sharma","doi":"10.3397/1/377129","DOIUrl":"https://doi.org/10.3397/1/377129","url":null,"abstract":"Additive manufacturing allows the fabrication of acoustical materials with previously unrealizable micro- and macrostructural complexities. However, the still nascent understanding of various geometrical defects occurring during the additive process remains a barrier to accurately predicting the acoustical behavior of such complex absorbers. In this study, we present the results from our efforts on numerically modeling the absorption behavior of periodic porous absorbers fabricated using the stereolithography (SLA) technique using the hybrid micro-macro multiphysics approach. Specifically, we focus on understanding the role played by the expansion or shrinkage of the solid ligaments during the SLA process on the acoustical properties of the final printed samples. First, the periodic absorbers are modeled using COMSOL multiphysics, where the transport properties are derived using the micro-modeling method and sound absorption behavior using the Johnson-Champoux-Allard-Lafarge-Pride semi-empirical model. Then, results from the expansion study guide the changes in the ligament sizes in the unit cell modeling. Finally, the fabricated samples are tested using an impedance tube, and the measured absorption properties are compared to the a priori numerical predictions. Results indicate that accounting for fabrication defects within the numerical modeling schema can provide reliable sound absorption predictions for additively manufactured porous absorbers.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135687197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zacharie Laly, Christopher Mechefske, Sebastian Ghinet, Charly T. Kone, Noureddine Atalla
In this article, a design of acoustic metamaterial containing Helmholtz resonators periodically embedded in a porous material is investigated for aerospace applications using the finite element method (FEM). The results obtained using the FEM are compared with the results of the theory, and the proposed transfer matrix method and good agreements are obtained. The transfer matrix method was combined with FEM calculations for two different termination conditions (plane wave radiation and rigid wall) in order to retrieve the equivalent matrix of the porous layer with the integrated periodic resonator. The equivalent matrix is then coupled analytically in series with others matrices. Finite element method studies are carried out on single and double wall configurations, and the effects of different resonator parameters and the air gap on the transmission loss are illustrated. The influences of the orientation of the neck opening and the resistivity of the porous material are also studied. Finite element method results for different incident angles are presented for single and double wall configurations. The proposed design can potentially be integrated into the panels of aircraft cabins in order to reduce the noise level at low frequencies inside the cabin.
{"title":"Design and analysis of periodic acoustic metamaterial sound insulator using finite element method","authors":"Zacharie Laly, Christopher Mechefske, Sebastian Ghinet, Charly T. Kone, Noureddine Atalla","doi":"10.3397/1/377128","DOIUrl":"https://doi.org/10.3397/1/377128","url":null,"abstract":"In this article, a design of acoustic metamaterial containing Helmholtz resonators periodically embedded in a porous material is investigated for aerospace applications using the finite element method (FEM). The results obtained using the FEM are compared with the results of the theory, and the proposed transfer matrix method and good agreements are obtained. The transfer matrix method was combined with FEM calculations for two different termination conditions (plane wave radiation and rigid wall) in order to retrieve the equivalent matrix of the porous layer with the integrated periodic resonator. The equivalent matrix is then coupled analytically in series with others matrices. Finite element method studies are carried out on single and double wall configurations, and the effects of different resonator parameters and the air gap on the transmission loss are illustrated. The influences of the orientation of the neck opening and the resistivity of the porous material are also studied. Finite element method results for different incident angles are presented for single and double wall configurations. The proposed design can potentially be integrated into the panels of aircraft cabins in order to reduce the noise level at low frequencies inside the cabin.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135687199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Srinivasa Ippili, Matthew B. Russell, Peng Wang, David W. Herrin
Early identification of rotating machinery faults is crucial to avoid catastrophic fail- ures upon installation. Contact-based vibration acquisition approaches are traditionally used for the purpose of machine health monitoring and end-of-line quality control. In complex working conditions, it can be difficult to perform an accurate accelerometer based vibration test. Acoustic signals (sound pressure and particle velocity) also contain important information about the operating state of mechanical equipment and can be used to detect different faults. A deep learning approach, namely, one-dimensional convolutional neural networks (1D-CNNs) can directly process raw time signals, thereby eliminating the human dependence on fault feature extraction. An experimental research study is conducted to test the proposed 1D-CNN methodology on three different electric motor faults. The results from the study indicate that the fault detection performance from the acoustic-based measurement method is very effective and thus can be a good replacement to the conventional accelerometer-based methods for detection and diagnosis of mechanical faults in electric motors.
{"title":"Deep learning-based mechanical fault detection and diagnosis of electric motors using directional characteristics of acoustic signals","authors":"Srinivasa Ippili, Matthew B. Russell, Peng Wang, David W. Herrin","doi":"10.3397/1/377132","DOIUrl":"https://doi.org/10.3397/1/377132","url":null,"abstract":"Early identification of rotating machinery faults is crucial to avoid catastrophic fail- ures upon installation. Contact-based vibration acquisition approaches are traditionally used for the purpose of machine health monitoring and end-of-line quality control. In complex working conditions, it can be difficult to perform an accurate accelerometer based vibration test. Acoustic signals (sound pressure and particle velocity) also contain important information about the operating state of mechanical equipment and can be used to detect different faults. A deep learning approach, namely, one-dimensional convolutional neural networks (1D-CNNs) can directly process raw time signals, thereby eliminating the human dependence on fault feature extraction. An experimental research study is conducted to test the proposed 1D-CNN methodology on three different electric motor faults. The results from the study indicate that the fault detection performance from the acoustic-based measurement method is very effective and thus can be a good replacement to the conventional accelerometer-based methods for detection and diagnosis of mechanical faults in electric motors.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135687295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaolong Li, Chihua Lu, Wan Chen, Yawei Zhu, Can Cheng
The noise reduction performance of the active road noise control (ARNC) system highly depends on the location of the reference sensors. Generally, the optimal sensor locations are evaluated by calculating the multiple coherence function (MCF) between all possible reference signal combinations with road noise. However, this trial-and- error method becomes time-consuming when the number of candidate locations is large. The transfer path analysis method can select the optimal sensor locations quickly while with low accuracy. Therefore, this article proposes two fast optimal sensor placement (FOSP) methods, namely, Wiener filter (WF)-FOSPand the MCF-FOSP, respectively. In both methods, the sensors are iteratively extended to the desired number, and each added sensor maximizes the predicted noise reduction of this iteration loop. Numerous ARNC simulations based on measured signals are conducted to illustrate the performance of the proposed two methods in terms of efficiency and accuracy. The results demonstrate that the WF-FOSP method provides the best comprehensive performance. The data analysis for one operating condition takes three minutes, and the absolute error is within 5% with respect to the benchmark. In addition, two schemes are discussed to obtain a set of sensor locations compatible with the noise reduction requirement of different operating conditions. The sensor locations can achieve a maximum average noise reduction of 7.29 dB(A) under four operating conditions.
{"title":"Research on fast optimal reference sensor placement in active road noise control","authors":"Xiaolong Li, Chihua Lu, Wan Chen, Yawei Zhu, Can Cheng","doi":"10.3397/1/377126","DOIUrl":"https://doi.org/10.3397/1/377126","url":null,"abstract":"The noise reduction performance of the active road noise control (ARNC) system highly depends on the location of the reference sensors. Generally, the optimal sensor locations are evaluated by calculating the multiple coherence function (MCF) between all possible reference signal combinations with road noise. However, this trial-and- error method becomes time-consuming when the number of candidate locations is large. The transfer path analysis method can select the optimal sensor locations quickly while with low accuracy. Therefore, this article proposes two fast optimal sensor placement (FOSP) methods, namely, Wiener filter (WF)-FOSPand the MCF-FOSP, respectively. In both methods, the sensors are iteratively extended to the desired number, and each added sensor maximizes the predicted noise reduction of this iteration loop. Numerous ARNC simulations based on measured signals are conducted to illustrate the performance of the proposed two methods in terms of efficiency and accuracy. The results demonstrate that the WF-FOSP method provides the best comprehensive performance. The data analysis for one operating condition takes three minutes, and the absolute error is within 5% with respect to the benchmark. In addition, two schemes are discussed to obtain a set of sensor locations compatible with the noise reduction requirement of different operating conditions. The sensor locations can achieve a maximum average noise reduction of 7.29 dB(A) under four operating conditions.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135687191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In real-world applications of active noise control (ANC) systems, various constraints are supposed to be satisfied in the controller design process. The optimal control filter coefficients can be obtained by solving a constrained optimization problem, which usually requires a significant computational effort. Recently, a convex formulation in conic form was proposed for ANC filter design. The proposed formulation was shown to result in a computational time reduction by several orders of magnitude. It is of great interest to further improve its efficiency by using a priori information of the optimal filter coefficients. One potential way of achieving this goal is to introduce a warmstart technique so that the filter solution of a similar system or environment can be referred to for selecting the starting point of the optimization algorithm. However, the conic formulation should be solved by the interior-point method, which, in general, is challenging for applying warmstart techniques. In the current work, relaxation methods are proposed to the constraints of original ANC filter design formulation so that the warmstart techniques can be applied. Then, a warmstarting technique proposed in previous study is used to solve a series of perturbed problems, and the performance of the warmstarting technique is investigated. Results show that with the proposed modifications applied, the warmstarting strategy can significantly reduce the number of iterations needed for solving the conic formulation of the ANC filter design problem without much tuning efforts, and the method is effective and robust in various environmental setups.
{"title":"Warmstarting strategies for convex optimization based multi-channel constrained active noise control filter design","authors":"Yongjie Zhuang, Zhuang Mo, Yangfan Liu","doi":"10.3397/1/377127","DOIUrl":"https://doi.org/10.3397/1/377127","url":null,"abstract":"In real-world applications of active noise control (ANC) systems, various constraints are supposed to be satisfied in the controller design process. The optimal control filter coefficients can be obtained by solving a constrained optimization problem, which usually requires a significant computational effort. Recently, a convex formulation in conic form was proposed for ANC filter design. The proposed formulation was shown to result in a computational time reduction by several orders of magnitude. It is of great interest to further improve its efficiency by using a priori information of the optimal filter coefficients. One potential way of achieving this goal is to introduce a warmstart technique so that the filter solution of a similar system or environment can be referred to for selecting the starting point of the optimization algorithm. However, the conic formulation should be solved by the interior-point method, which, in general, is challenging for applying warmstart techniques. In the current work, relaxation methods are proposed to the constraints of original ANC filter design formulation so that the warmstart techniques can be applied. Then, a warmstarting technique proposed in previous study is used to solve a series of perturbed problems, and the performance of the warmstarting technique is investigated. Results show that with the proposed modifications applied, the warmstarting strategy can significantly reduce the number of iterations needed for solving the conic formulation of the ANC filter design problem without much tuning efforts, and the method is effective and robust in various environmental setups.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135687194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mark C. Anderson, Kent L. Gee, J. Taggart Durrant, Alexandra Loubeau
Brigham Young University has been investigating best practices for recommendation to NASA in upcoming X-59 sonic thump measurements. This preparatory work has focused both on obtaining high-fidelity data and standardizing signal analysis techniques for sonic thumps. Included in the research are topics such as whether to use a ground-based or elevated microphone, how to use low-noise microphones and still recover high-fidelity data at low frequencies, and estimating the uncertainty in a given measurement due to local atmospheric turbulence effects. Also included is a study of windowing techniques, zero padding, and the removal of high-frequency ambient noise contamination.
杨百翰大学(Brigham Young University)一直在研究向NASA推荐即将到来的X-59声压测量的最佳实践。这项准备工作的重点是获得高保真数据和标准化的信号分析技术。研究的主题包括是使用地面麦克风还是高空麦克风，如何使用低噪声麦克风并在低频率下恢复高保真数据，以及估计由于局部大气湍流影响而在给定测量中的不确定性。还包括窗技术，零填充和去除高频环境噪声污染的研究。
{"title":"Toward high-quality X-59 sonic thump measurements","authors":"Mark C. Anderson, Kent L. Gee, J. Taggart Durrant, Alexandra Loubeau","doi":"10.3397/1/377130","DOIUrl":"https://doi.org/10.3397/1/377130","url":null,"abstract":"Brigham Young University has been investigating best practices for recommendation to NASA in upcoming X-59 sonic thump measurements. This preparatory work has focused both on obtaining high-fidelity data and standardizing signal analysis techniques for sonic thumps. Included in the research are topics such as whether to use a ground-based or elevated microphone, how to use low-noise microphones and still recover high-fidelity data at low frequencies, and estimating the uncertainty in a given measurement due to local atmospheric turbulence effects. Also included is a study of windowing techniques, zero padding, and the removal of high-frequency ambient noise contamination.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135687294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamic properties of hydraulic bushings are often modeled in the time and frequency domains with low-order, lumped-parameter models, typically assuming steady developed flow in their fluid passages, whereas in situ flow conditions are unlikely to meet such criteria. Hydraulic bushings exhibit tuned properties emerging from nonlinear interactions involving these flow characteristics, so higher resolution descriptions of the underlying physics are needed under realistic flow conditions. This paper discusses an approach to isolate the fluid passage features in production bushings to enable experimental characterization for steady, oscillatory, and transient flow. More robust models of dynamic responses in the time and frequency domains are expected to result from this more precise determination of each flow path's contribution to the nonlinear system response. An apparatus capable of generating steady and dynamic flow is proposed, and some validation data are given to demonstrate the functionality of the experiment. Some challenges with the approach are considered, including the system's hydraulic compliance and cavitation. The flow testing apparatus is used on an example two-passage production bushing adapted for controlled steady or dynamic flow through one or both flow paths. Finally, some nonlinear flow properties of a typical hydraulic bushing's flow passages are given.
{"title":"Experimental dynamic flow characterization of hydraulic bushings","authors":"Britton DeGarmo, Michael Kennedy, Luke Fredette","doi":"10.3397/1/377131","DOIUrl":"https://doi.org/10.3397/1/377131","url":null,"abstract":"The dynamic properties of hydraulic bushings are often modeled in the time and frequency domains with low-order, lumped-parameter models, typically assuming steady developed flow in their fluid passages, whereas in situ flow conditions are unlikely to meet such criteria. Hydraulic bushings exhibit tuned properties emerging from nonlinear interactions involving these flow characteristics, so higher resolution descriptions of the underlying physics are needed under realistic flow conditions. This paper discusses an approach to isolate the fluid passage features in production bushings to enable experimental characterization for steady, oscillatory, and transient flow. More robust models of dynamic responses in the time and frequency domains are expected to result from this more precise determination of each flow path's contribution to the nonlinear system response. An apparatus capable of generating steady and dynamic flow is proposed, and some validation data are given to demonstrate the functionality of the experiment. Some challenges with the approach are considered, including the system's hydraulic compliance and cavitation. The flow testing apparatus is used on an example two-passage production bushing adapted for controlled steady or dynamic flow through one or both flow paths. Finally, some nonlinear flow properties of a typical hydraulic bushing's flow passages are given.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135687293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In many daily communication environments, especially during a pandemic era, partitioning structures are placed between people for security or virus concerns, for example, partitions in classrooms, banks, and retail stores. Distortion occurs when sound propagates through these partitions, which can cause distractions in communication and degrade the service quality. In the current work, a constrained multi-channel active hear-through system is proposed to provide a solution to provide more natural sound communication environments and prevent sound distortions due to partitioning structures. The proposed method can preserve both the spectrum and the spatial distribution of the original sound field (the sound field when the partition is absent). This research opens the potential for future development of multi-channel two-way communication systems and improvement in existing augmented reality techniques. Experimental results show that, compared with the traditional direct inverse filter design method, the proposed method can reduce the comb-filtering effect effectively. The constraints applied to the filter design procedure can also prevent instability caused by the acoustic feedback loop.
{"title":"A constrained multi-channel hear-through filter design approach using active control formulations","authors":"Juhyung Kim, Yongjie Zhuang, Yangfan Liu","doi":"10.3397/1/377133","DOIUrl":"https://doi.org/10.3397/1/377133","url":null,"abstract":"In many daily communication environments, especially during a pandemic era, partitioning structures are placed between people for security or virus concerns, for example, partitions in classrooms, banks, and retail stores. Distortion occurs when sound propagates through these partitions, which can cause distractions in communication and degrade the service quality. In the current work, a constrained multi-channel active hear-through system is proposed to provide a solution to provide more natural sound communication environments and prevent sound distortions due to partitioning structures. The proposed method can preserve both the spectrum and the spatial distribution of the original sound field (the sound field when the partition is absent). This research opens the potential for future development of multi-channel two-way communication systems and improvement in existing augmented reality techniques. Experimental results show that, compared with the traditional direct inverse filter design method, the proposed method can reduce the comb-filtering effect effectively. The constraints applied to the filter design procedure can also prevent instability caused by the acoustic feedback loop.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135687195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, the band gaps in a mass-spring structure composed of resonator with elastic support are investigated. The band structure, effective parameters, and transmission spectra of the acoustic metamaterials are calculated numerically. The numerical results show that the elastic support and resonator in the structure generate the first and the second band gap, respectively. The effective parameters are analyzed to reveal the nature of this phenomenon and calculated to obtain the edge frequencies of band gaps. The transmission spectra are in accordance with the complex band structure. It is found that the attenuation factor is non-zero in band gap, and it determines the shape and magnitude of transmission ratio in band gap. The influences of the structural parameters on the band structure and attenuation factor are investigated numerically. Numerical results show that the band structure can be modulated by changing the structural parameters, and the topological structure will be changed when those parameters change greatly.
{"title":"Band gaps in an acoustic metamaterial composed of resonator with elastic support","authors":"Shengping Fan, Jing Li, Linyong Li, Xiaopeng Fan, Hualiang Li, Nansha Gao","doi":"10.3397/1/377121","DOIUrl":"https://doi.org/10.3397/1/377121","url":null,"abstract":"In this paper, the band gaps in a mass-spring structure composed of resonator with elastic support are investigated. The band structure, effective parameters, and transmission spectra of the acoustic metamaterials are calculated numerically. The numerical results show that the elastic\u0000 support and resonator in the structure generate the first and the second band gap, respectively. The effective parameters are analyzed to reveal the nature of this phenomenon and calculated to obtain the edge frequencies of band gaps. The transmission spectra are in accordance with the complex\u0000 band structure. It is found that the attenuation factor is non-zero in band gap, and it determines the shape and magnitude of transmission ratio in band gap. The influences of the structural parameters on the band structure and attenuation factor are investigated numerically. Numerical results\u0000 show that the band structure can be modulated by changing the structural parameters, and the topological structure will be changed when those parameters change greatly.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48448923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Noise of internal combustion engine is the main source of noise pollution, and mufflers are the main means to reduce exhaust noise of internal combustion engine. In the process of improving the acoustic performance of the exhaust muffler based on the three-dimensional numerical method, the influence of the high speed and high temperature airflow discharged by the engine in the actual working process on the acoustic performance of the exhaust muffler is often ignored, which leads to the obvious deviation between the predicted results and the actual situation. In this paper, based on the structural optimization design of the straight-through perforated pipe resistance muffler, the noise characteristics of the straight-through perforated pipe resistance muffler with perforated corrugated lining was analyzed considering the airflow velocity and temperature inside the muffler. The influence of temperature and velocity fields on the acoustic performance of muffler was studied by using numerical simulation method, which takes the solution results inside muffler as boundary conditions of sound field analysis. The influence of changing the internal structure of muffler on the aerodynamic performance of muffler was discussed, and the pressure loss is analyzed. The research has shown that adding perforated corrugated lining inside muffler could effectively improve the transmission loss of muffler and the noise reduction performance of prototype straight-through perforated pipe-resistant muffler.
{"title":"Case study: Noise attenuating performance of perforated corrugated lined straight-through perforated pipe-resistant muffler","authors":"Zhenhua Hou, Qigan Wang, Tengfei Si, Shiqiang Zhang","doi":"10.3397/1/377123","DOIUrl":"https://doi.org/10.3397/1/377123","url":null,"abstract":"Noise of internal combustion engine is the main source of noise pollution, and mufflers are the main means to reduce exhaust noise of internal combustion engine. In the process of improving the acoustic performance of the exhaust muffler based on the three-dimensional numerical method, the influence of the high speed and high temperature airflow discharged by the engine in the actual working process on the acoustic performance of the exhaust muffler is often ignored, which leads to the obvious deviation between the predicted results and the actual situation. In this paper, based on the structural optimization design of the straight-through perforated pipe resistance muffler, the noise characteristics of the straight-through perforated pipe resistance muffler with perforated corrugated lining was analyzed considering the airflow velocity and temperature inside the muffler. The influence of temperature and velocity fields on the acoustic performance of muffler was studied by using numerical simulation method, which takes the solution results inside muffler as boundary conditions of sound field analysis. The influence of changing the internal structure of muffler on the aerodynamic performance of muffler was discussed, and the pressure loss is analyzed. The research has shown that adding perforated corrugated lining inside muffler could effectively improve the transmission loss of muffler and the noise reduction performance of prototype straight-through perforated pipe-resistant muffler.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135761898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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