Pub Date : 2023-07-20DOI: 10.24425/aoa.2022.141652
D. Tounsi, W. Taktak, R. Dhief, M. Haddar
Duct silencers provide effective noise reduction for heating, ventilation and air conditioning systems. These silencers can achieve an excellent sound attenuation through the attributes of their design. The reactive silencer works on the principle of high reflection of sound waves at low frequencies. On the other hand, the dissipative silencer works on the principle of sound absorption, which is very effective at high-frequencies. Combining these two kinds of silencers allowed covering the whole frequency range. In this paper, the effect of liner characteristics composed of a perforated plate backed by a porous material and geometry discontinuities on the acoustic power attenuation of lined ducts is evaluated. This objective is achieved by using a numerical model to compute the multimodal scattering matrix, thus allowing deducing the acoustic power attenuation. The numerical results are obtained for six configurations, including cases of narrowing and widening of a radius duct with sudden or progressive discontinuities. Numerical acoustic power attenuation shows the relative influence of the variation in the values of each parameter of the liner, and of each type of radius discontinuities of ducts.
{"title":"Evaluation of the Acoustic Performance of Porous Materials Lined Ducts with Geometric Discontinuities","authors":"D. Tounsi, W. Taktak, R. Dhief, M. Haddar","doi":"10.24425/aoa.2022.141652","DOIUrl":"https://doi.org/10.24425/aoa.2022.141652","url":null,"abstract":"Duct silencers provide effective noise reduction for heating, ventilation and air conditioning systems. These silencers can achieve an excellent sound attenuation through the attributes of their design. The reactive silencer works on the principle of high reflection of sound waves at low frequencies. On the other hand, the dissipative silencer works on the principle of sound absorption, which is very effective at high-frequencies. Combining these two kinds of silencers allowed covering the whole frequency range. In this paper, the effect of liner characteristics composed of a perforated plate backed by a porous material and geometry discontinuities on the acoustic power attenuation of lined ducts is evaluated. This objective is achieved by using a numerical model to compute the multimodal scattering matrix, thus allowing deducing the acoustic power attenuation. The numerical results are obtained for six configurations, including cases of narrowing and widening of a radius duct with sudden or progressive discontinuities. Numerical acoustic power attenuation shows the relative influence of the variation in the values of each parameter of the liner, and of each type of radius discontinuities of ducts.","PeriodicalId":8149,"journal":{"name":"Archives of Acoustics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42933707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/aoa.2021.139646
Paweł, K. Anna, Jędrzej, Adam
4th order ambisonic microphone in acoustic field analysis
声场分析中的四阶双声传声器
{"title":"67th Open Seminar on Acoustics September 14 – 17, 2021","authors":"Paweł, K. Anna, Jędrzej, Adam","doi":"10.24425/aoa.2021.139646","DOIUrl":"https://doi.org/10.24425/aoa.2021.139646","url":null,"abstract":"4th order ambisonic microphone in acoustic field analysis","PeriodicalId":8149,"journal":{"name":"Archives of Acoustics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44493772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/aoa.2021.139643
Łukasz Gorazd
The aim of the paper is to experimentally determine the scattering matrix S of an example reflective muffler of cylindrical geometry for Helmholtz number exceeding the plane wave propagation. Determining the scattering matrix of an acoustic systems is a new and increasingly used approach in the assessment of reduction of noise propagating inside duct-like elements of heating, ventilation and air conditioning systems (HVAC). The scattering matrix of an acoustic system provides all necessary information on the propagation of wave through it. In case of the analysed reflective silencer, considered as a two-port system, the noise reduction was determined by calculating the transmission loss parameter (TL) based on the scattering matrix ( S ). Measurements were carried out in two planes of the cross-section of pipes connected to the muffler. Thepaper presents results of the scattering matrix evaluation for the wave composed of the plane wave (mode (0,0)) and the first radial mode (0,1), each of which was generated separately using the self-designed and constructed single-mode generator. The gain of proceeding measurements for single modes stems from the fact that theoretically, calculation of the S -matrix does not require, as will be presented in the paper, calculation of the measurement data inverse matrix. Moreover, if single mode sound fields are well determined, it ensures error minimization. The presented measurement results refer to an example of a duct like system with a reflective muffler for which the scattering matrix S was determined. The acoustic phenomena inside such a system can be scaled by the parameter ka .
{"title":"Experimental Determination of a Reflective Muffler Scattering Matrix for Single-Mode Excitation","authors":"Łukasz Gorazd","doi":"10.24425/aoa.2021.139643","DOIUrl":"https://doi.org/10.24425/aoa.2021.139643","url":null,"abstract":"The aim of the paper is to experimentally determine the scattering matrix S of an example reflective muffler of cylindrical geometry for Helmholtz number exceeding the plane wave propagation. Determining the scattering matrix of an acoustic systems is a new and increasingly used approach in the assessment of reduction of noise propagating inside duct-like elements of heating, ventilation and air conditioning systems (HVAC). The scattering matrix of an acoustic system provides all necessary information on the propagation of wave through it. In case of the analysed reflective silencer, considered as a two-port system, the noise reduction was determined by calculating the transmission loss parameter (TL) based on the scattering matrix ( S ). Measurements were carried out in two planes of the cross-section of pipes connected to the muffler. Thepaper presents results of the scattering matrix evaluation for the wave composed of the plane wave (mode (0,0)) and the first radial mode (0,1), each of which was generated separately using the self-designed and constructed single-mode generator. The gain of proceeding measurements for single modes stems from the fact that theoretically, calculation of the S -matrix does not require, as will be presented in the paper, calculation of the measurement data inverse matrix. Moreover, if single mode sound fields are well determined, it ensures error minimization. The presented measurement results refer to an example of a duct like system with a reflective muffler for which the scattering matrix S was determined. The acoustic phenomena inside such a system can be scaled by the parameter ka .","PeriodicalId":8149,"journal":{"name":"Archives of Acoustics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44229876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/aoa.2022.142891
A. Brański, Romuald Kuras
The article extended the idea of active vibration reduction of beams with symmetric modes to beams with asymmetric modes. In the case of symmetric modes, the symmetric PZT (s-PZT) was used, and the optimization of the problem led to the location of the s-PZT centre at the point with the greatest beam curvature. In the latter case, the asymmetric modes that occur due to the addition of the point mass cause an asymmetric distribution of the bending moment and transversal displacement of a beam. In this case, the optimal approach to the active vibration reduction requires both new asymmetric PZT (a-PZT) and its new particular distribution on the beam. It has been mathematically determined that the a-PZT asymmetry point (a-point), ought to be placed at the point of maximum beam bending moment. The a-PZT asymmetry was found mathematically by minimizing the amplitude of the vibrations. As a result, it was possible to formulate the criterion of the maximum bending moment of the beam. The numerical calculations confirmed theoretical considerations. So, it was shown that in the case of asymmetric vibrations, the a-PZTs reduced vibrations more efficiently than the s-PZT.
{"title":"Asymmetrical PZT applied to active reduction of asymmetrically vibrating beam – semi-analytical solution","authors":"A. Brański, Romuald Kuras","doi":"10.24425/aoa.2022.142891","DOIUrl":"https://doi.org/10.24425/aoa.2022.142891","url":null,"abstract":"The article extended the idea of active vibration reduction of beams with symmetric modes to beams with asymmetric modes. In the case of symmetric modes, the symmetric PZT (s-PZT) was used, and the optimization of the problem led to the location of the s-PZT centre at the point with the greatest beam curvature. In the latter case, the asymmetric modes that occur due to the addition of the point mass cause an asymmetric distribution of the bending moment and transversal displacement of a beam. In this case, the optimal approach to the active vibration reduction requires both new asymmetric PZT (a-PZT) and its new particular distribution on the beam. It has been mathematically determined that the a-PZT asymmetry point (a-point), ought to be placed at the point of maximum beam bending moment. The a-PZT asymmetry was found mathematically by minimizing the amplitude of the vibrations. As a result, it was possible to formulate the criterion of the maximum bending moment of the beam. The numerical calculations confirmed theoretical considerations. So, it was shown that in the case of asymmetric vibrations, the a-PZTs reduced vibrations more efficiently than the s-PZT.","PeriodicalId":8149,"journal":{"name":"Archives of Acoustics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43251018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/aoa.2023.144266
{"title":"Evaluation of the Effect of Uncertainties on the Acoustic Behavior of a Porous Material Located in a Duct Element Using the Monte Carlo Method","authors":"","doi":"10.24425/aoa.2023.144266","DOIUrl":"https://doi.org/10.24425/aoa.2023.144266","url":null,"abstract":"","PeriodicalId":8149,"journal":{"name":"Archives of Acoustics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45787853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/aoa.2022.142902
{"title":"Professor Józef Lewandowski","authors":"","doi":"10.24425/aoa.2022.142902","DOIUrl":"https://doi.org/10.24425/aoa.2022.142902","url":null,"abstract":"","PeriodicalId":8149,"journal":{"name":"Archives of Acoustics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47981994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/aoa.2022.142895
W. Rdzanek, K. Szemela
This study presents an analysis of the effect of the concentrated mass on the acoustic power and the resonant frequencies of a vibrating thin circular plate. The fluid-structure interactions and the acoustic wave radiation effect have been included. The eigenfunction expansion has been used to express the transverse displacement of the plate. The appropriate number of modes is determined approximately to achieve physically correct results. Then highly accurate results are obtained numerically. The radiated acoustic power has been used to determine the resonant frequencies. The introducing of the concentrated mass is justified by modelling the added mass of the moving component of the exciter.
{"title":"The effect of a concentrated mass on the acoustic power and the resonant frequencies of a circular plate","authors":"W. Rdzanek, K. Szemela","doi":"10.24425/aoa.2022.142895","DOIUrl":"https://doi.org/10.24425/aoa.2022.142895","url":null,"abstract":"This study presents an analysis of the effect of the concentrated mass on the acoustic power and the resonant frequencies of a vibrating thin circular plate. The fluid-structure interactions and the acoustic wave radiation effect have been included. The eigenfunction expansion has been used to express the transverse displacement of the plate. The appropriate number of modes is determined approximately to achieve physically correct results. Then highly accurate results are obtained numerically. The radiated acoustic power has been used to determine the resonant frequencies. The introducing of the concentrated mass is justified by modelling the added mass of the moving component of the exciter.","PeriodicalId":8149,"journal":{"name":"Archives of Acoustics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48812346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/aoa.2022.142908
N. Mohammadi
In the current study, investigations are made to control the MB truck cabin interior noise by reducing noise in the transmission path. The main sources of cabin noise include the engine, exhaust system, air inlet system, driveline system, and tyres (especially at higher speeds). Furthermore, vibrations of the body and interior parts of the truck may significantly impact the overall in-cabin sound level. Noise is transmitted into the cabin via air (airborne noise) and cabin structure (structure-borne noise). In the noise treatment phase, noise transmission paths are considered. A viscoelastic layer damping material is used to reduce the vibration amplitude of the cabin back wall. The overall loss factor and vibration amplitude reduction ratio for the structure treated is calculated. Computational results are then compared with the values obtained by the experimental modal analysis results. Choosing the suitable material and thickness can significantly reduce the vibration amplitude. A sound barrier, silicon adhesive, and foam are also utilised for noise control in the transmission path. The effectiveness of the mentioned acoustic materials on cabin noise reduction is evaluated experimentally. The experimental SPL values are reported in the frequency range of 20 Hz–20 kHz based on a 1/3 octave filter. The experimental results show that using acoustics materials reduces the overall in-cabin sound level for a wide range of frequencies.
{"title":"Airborne and Structure-Borne Noise Control in the MB Truck Cabin Interior by the Noise Reduction in the Transmission Path","authors":"N. Mohammadi","doi":"10.24425/aoa.2022.142908","DOIUrl":"https://doi.org/10.24425/aoa.2022.142908","url":null,"abstract":"In the current study, investigations are made to control the MB truck cabin interior noise by reducing noise in the transmission path. The main sources of cabin noise include the engine, exhaust system, air inlet system, driveline system, and tyres (especially at higher speeds). Furthermore, vibrations of the body and interior parts of the truck may significantly impact the overall in-cabin sound level. Noise is transmitted into the cabin via air (airborne noise) and cabin structure (structure-borne noise). In the noise treatment phase, noise transmission paths are considered. A viscoelastic layer damping material is used to reduce the vibration amplitude of the cabin back wall. The overall loss factor and vibration amplitude reduction ratio for the structure treated is calculated. Computational results are then compared with the values obtained by the experimental modal analysis results. Choosing the suitable material and thickness can significantly reduce the vibration amplitude. A sound barrier, silicon adhesive, and foam are also utilised for noise control in the transmission path. The effectiveness of the mentioned acoustic materials on cabin noise reduction is evaluated experimentally. The experimental SPL values are reported in the frequency range of 20 Hz–20 kHz based on a 1/3 octave filter. The experimental results show that using acoustics materials reduces the overall in-cabin sound level for a wide range of frequencies.","PeriodicalId":8149,"journal":{"name":"Archives of Acoustics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47155962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.24425/aoa.2022.142014
M. Khalilabadi
In this paper, a 2D numerical modeling of sound wave propagation in a shallow water medium that acts as a waveguide, are presented. This modeling is based on the method of characteristic which is not constrained by the Courant–Friedrichs–Lewy (CFL) condition. Using this method, the Euler time-dependent equations have been solved under adiabatic conditions inside of a shallow water waveguide which is consists of one homogeneous environment of water over a rigid bed. In this work, the stability and precision of the method of characteristics (MOC) technique for sound wave propagation in a waveguide were illustrated when it was applied with the semi-Lagrange method. The results show a significant advantage of the method of characteristics over the finite difference time domain (FDTD) method.
{"title":"2D Modeling of Wave Propagation in Shallow Water by the Method of Characteristics","authors":"M. Khalilabadi","doi":"10.24425/aoa.2022.142014","DOIUrl":"https://doi.org/10.24425/aoa.2022.142014","url":null,"abstract":"In this paper, a 2D numerical modeling of sound wave propagation in a shallow water medium that acts as a waveguide, are presented. This modeling is based on the method of characteristic which is not constrained by the Courant–Friedrichs–Lewy (CFL) condition. Using this method, the Euler time-dependent equations have been solved under adiabatic conditions inside of a shallow water waveguide which is consists of one homogeneous environment of water over a rigid bed. In this work, the stability and precision of the method of characteristics (MOC) technique for sound wave propagation in a waveguide were illustrated when it was applied with the semi-Lagrange method. The results show a significant advantage of the method of characteristics over the finite difference time domain (FDTD) method.","PeriodicalId":8149,"journal":{"name":"Archives of Acoustics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41677902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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