The illusion force perceived by exciting asymmetric vibration has been studied, and the kinesthetic effect is recently clarified to be largely influenced by the asymmetry of the excited vibration waveforms. However, it has not yet been investigated how the extent of asymmetry influenced the perception of the illusion force. In this study, the effect of the asymmetry of the input vibration waveform on the extent of induced traction force was experimentally investigated by changing the extent of asymmetry that is controlled by the summation order of Fourier series expansion of the original waveform. As a result, it was confirmed that the extent of induced traction form increases as the extent of asymmetry of the actuated sawtooth waveform increases up to the summation order of 3; however, the induced traction form does not increase in case of n of over 4.
{"title":"Case study: Effect of asymmetry of vibration on the perceived illusion force","authors":"T. Asakura, H. Hirasawa","doi":"10.3397/1/377020","DOIUrl":"https://doi.org/10.3397/1/377020","url":null,"abstract":"The illusion force perceived by exciting asymmetric vibration has been studied, and the kinesthetic effect is recently clarified to be largely influenced by the asymmetry of the excited vibration waveforms. However, it has not yet been investigated how the extent of asymmetry influenced\u0000 the perception of the illusion force. In this study, the effect of the asymmetry of the input vibration waveform on the extent of induced traction force was experimentally investigated by changing the extent of asymmetry that is controlled by the summation order of Fourier series expansion\u0000 of the original waveform. As a result, it was confirmed that the extent of induced traction form increases as the extent of asymmetry of the actuated sawtooth waveform increases up to the summation order of 3; however, the induced traction form does not increase in case of n of over 4.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49483248","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}
This paper presents a case study for measuring and simulating the vibration and radiated sound for a large complex industrial chiller. We describe a simulation framework based on statistical energy analysis (SEA), which is populated using a hybrid mix of analytic, numerical, and measurement techniques. This hybrid approach was motivated by preliminary measurements of vibration and sound from the operating chiller, as well as a series of vibroacoustic transfer functions measured during quiescent non-operating conditions. Some components, like the chiller condenser shell, are modally dense and well suited to statistical estimates of SEA parameters like modal density and coupling between the shell modes and internal and external acoustic spaces. Other components, like the discharge pipe between the compressor and condenser shell, have only a few well separated modes with low damping. This component is better modeled using mobilities either measured or calculated using finite element analysis. We estimate other parameters like internal and coupling loss factors using a mix of analytics and measurements where appropriate. We validate the general model by comparing simulated and measured transfer functions between the discharge pipe and condenser shell — the components that radiated the most sound. We estimate structure-borne and fluid-borne input powers from the compressor using inference techniques based on transfer function measurements at quiescent conditions and averaged surface vibrations measured at operating conditions. This inference approach allows for estimating input powers over any chiller operating condition. Simulated vibrations and radiated sound are generally within 3 dB of measurements for several operating conditions. This case study provides a useful general methodology for modeling and measuring the vibroacoustics of chillers and other complex machinery
{"title":"Case study: Simulating and measuring the vibration and radiated sound of a large industrial chiller","authors":"S. Wells, S. Hambric, T. Brungart","doi":"10.3397/1/377017","DOIUrl":"https://doi.org/10.3397/1/377017","url":null,"abstract":"This paper presents a case study for measuring and simulating the vibration and radiated sound for a large complex industrial chiller. We describe a simulation framework based on statistical energy analysis (SEA), which is populated using a hybrid mix of analytic, numerical, and measurement\u0000 techniques. This hybrid approach was motivated by preliminary measurements of vibration and sound from the operating chiller, as well as a series of vibroacoustic transfer functions measured during quiescent non-operating conditions. Some components, like the chiller condenser shell, are modally\u0000 dense and well suited to statistical estimates of SEA parameters like modal density and coupling between the shell modes and internal and external acoustic spaces. Other components, like the discharge pipe between the compressor and condenser shell, have only a few well separated modes with\u0000 low damping. This component is better modeled using mobilities either measured or calculated using finite element analysis. We estimate other parameters like internal and coupling loss factors using a mix of analytics and measurements where appropriate. We validate the general model by comparing\u0000 simulated and measured transfer functions between the discharge pipe and condenser shell — the components that radiated the most sound. We estimate structure-borne and fluid-borne input powers from the compressor using inference techniques based on transfer function measurements at quiescent\u0000 conditions and averaged surface vibrations measured at operating conditions. This inference approach allows for estimating input powers over any chiller operating condition. Simulated vibrations and radiated sound are generally within 3 dB of measurements for several operating conditions.\u0000 This case study provides a useful general methodology for modeling and measuring the vibroacoustics of chillers and other complex machinery","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46330028","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}
Because of the electric power transmission system has no sound masking effect compared with the traditional internal combustion power transmission system, electric powertrain noise has become the prominent noise of electric vehicles, adversely affecting the sound quality of the vehicle interior. Because of the strong coupling of motor and transmission noise, it is difficult to separate and identify the compositions of the electric powertrain by experiments. A psychoacoustic model is used to separate and identify the noise sources of the electric powertrain of a vehicle, considering the masking effect of the human ear. The electric powertrain noise is tested in a semi-anechoic chamber and recorded by a high-precision noise sensor. The noise source compositions of the electric powertrain are analyzed by the computational auditory scene analysis and robust independent component analysis. Five independent noise sources are obtained, i.e., the fundamental frequency of the first gear mesh noise, fundamental frequency of the second gear mesh noise, double frequency of the second gear mesh noise, radial electromagnetic force noise and stator slot harmonic noise. The results provide a guide for the optimization of the sound quality of the electric powertrain and for the improvement of the sound quality of the vehicle interior.
{"title":"Identification of prominent noise components of an electric powertrain using a psychoacoustic model","authors":"Yuebo He, Hui Gao, Hai Liu, Guoxi Jing","doi":"10.3397/1/37709","DOIUrl":"https://doi.org/10.3397/1/37709","url":null,"abstract":"Because of the electric power transmission system has no sound masking effect compared with the traditional internal combustion power transmission system, electric powertrain noise has become the prominent noise of electric vehicles, adversely affecting the sound quality of the vehicle\u0000 interior. Because of the strong coupling of motor and transmission noise, it is difficult to separate and identify the compositions of the electric powertrain by experiments. A psychoacoustic model is used to separate and identify the noise sources of the electric powertrain of a vehicle,\u0000 considering the masking effect of the human ear. The electric powertrain noise is tested in a semi-anechoic chamber and recorded by a high-precision noise sensor. The noise source compositions of the electric powertrain are analyzed by the computational auditory scene analysis and robust independent\u0000 component analysis. Five independent noise sources are obtained, i.e., the fundamental frequency of the first gear mesh noise, fundamental frequency of the second gear mesh noise, double frequency of the second gear mesh noise, radial electromagnetic force noise and stator slot harmonic noise.\u0000 The results provide a guide for the optimization of the sound quality of the electric powertrain and for the improvement of the sound quality of the vehicle interior.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43890249","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}
We performed a theoretical analysis on collection of equilateral triangular holes with consideration for sound wave attenuation within the tube and then calculated the sound-absorption coefficient and transmission loss. We then compared these results with experimental values. In the experiment, we measured the sound-absorption coefficient and transmission loss of a test sample using impedance measurement tubes with two and four microphones. We estimated the sound-absorption coefficient and transmission loss because of the dimensions of a collection of equilateral triangular holes through theoretical analysis and then compared these results with experimental values. In the present analysis, the propagation constant and characteristic impedance were introduced into a one-dimensional transfer matrix. Considering the effects of sound wave attenuation in the tubule from three-dimensional analysis, we derived the propagation constant and characteristic impedance. Values for the sound-absorption coefficient and transmission loss obtained through the analysis of holes as triangles rather than as circles gave calculation results closer to the experimental values. This is because this method more suitably simulates the effects of the boundary layer that occupies the space within the hole. The results show that the sound absorption coefficient and transmission loss of triangular honeycombs can be estimated with sufficient accuracy using only geometric dimensions and physical properties.
{"title":"Comparison of estimated and measured sound-absorption coefficient and transmission loss by geometric dimensions of a collection of equilateral triangular holes of equilateral triangular holes","authors":"Shuichi Sakamoto, Kouta Sutou, Arata Nakano, Hirohiko Tanikawa, Takanari Azami, Tetsushi Shintani","doi":"10.3397/1/377013","DOIUrl":"https://doi.org/10.3397/1/377013","url":null,"abstract":"We performed a theoretical analysis on collection of equilateral triangular holes with consideration for sound wave attenuation within the tube and then calculated the sound-absorption coefficient and transmission loss. We then compared these results with experimental values. In the\u0000 experiment, we measured the sound-absorption coefficient and transmission loss of a test sample using impedance measurement tubes with two and four microphones. We estimated the sound-absorption coefficient and transmission loss because of the dimensions of a collection of equilateral triangular\u0000 holes through theoretical analysis and then compared these results with experimental values. In the present analysis, the propagation constant and characteristic impedance were introduced into a one-dimensional transfer matrix. Considering the effects of sound wave attenuation in the tubule\u0000 from three-dimensional analysis, we derived the propagation constant and characteristic impedance. Values for the sound-absorption coefficient and transmission loss obtained through the analysis of holes as triangles rather than as circles gave calculation results closer to the experimental\u0000 values. This is because this method more suitably simulates the effects of the boundary layer that occupies the space within the hole. The results show that the sound absorption coefficient and transmission loss of triangular honeycombs can be estimated with sufficient accuracy using only\u0000 geometric dimensions and physical properties.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46574360","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}
Yixiao Li, Kun Chen, R. Gao, Jianhui Wei, Weiwei Yao
Many bio-inspired researches for aerodynamic noise control of wind turbine have been carried out and obtained effective results. Inspired by the silent flight of owl, in this paper, the airfoil of owl's wing and the asymmetric sawtooth structure of the feather have been extracted and reconstructed on the prototype wind turbine blades. The bionic airfoil blade and bionic coupling blade have been designed separately and compared with prototype blade. To obtain the asymmetric sawtooth structure with better acoustic performance, the sawtooth parameters are selected by orthogonal test. The influence of airfoil and asymmetric sawtooth for acoustic performance of blade has been investigated with large eddy simulation method and Ffowcs Williams-Hawkings analogy method. The results show that the bionic coupling blade has a larger surface pressure difference compared with the prototype blade and thus has better aerodynamic performance. The airfoil-structure coupling method can effectively reduce the aerodynamic noise of the blade without affecting the directivity of the acoustic, and optimized blade can reduce the noise by up to 8.42 dB. The blade coupling airfoil has an inhibitory effect on intermediate and high frequency noise. After adding asymmetric sawtooth trailing edge, the noise in the low frequency and intermediate frequency range is further reduced.
针对风力机气动噪声控制的仿生研究已经开展了很多，并取得了很好的效果。受猫头鹰无声飞行的启发，本文提取了猫头鹰翅膀的翼型和羽毛的非对称锯齿状结构，并在原型风力机叶片上进行了重构。分别设计了仿生翼型叶片和仿生耦合叶片，并与原型叶片进行了比较。为了获得具有较好声学性能的非对称锯齿结构，通过正交试验选择锯齿参数。采用大涡模拟方法和Ffowcs williams - hawkins类比法研究了翼型和非对称锯齿对叶片声学性能的影响。结果表明，与原型叶片相比，仿生耦合叶片具有更大的表面压差，从而具有更好的气动性能。采用翼型-结构耦合的方法可以在不影响声的方向性的情况下有效降低叶片的气动噪声，优化后的叶片噪声降低幅度高达8.42 dB。叶片耦合翼型对中高频噪声具有抑制作用。加入非对称锯齿尾缘后，进一步降低了低频和中频噪声。
{"title":"Noise reduction of bionic coupling blades of horizontal axis wind turbine","authors":"Yixiao Li, Kun Chen, R. Gao, Jianhui Wei, Weiwei Yao","doi":"10.3397/1/377015","DOIUrl":"https://doi.org/10.3397/1/377015","url":null,"abstract":"Many bio-inspired researches for aerodynamic noise control of wind turbine have been carried out and obtained effective results. Inspired by the silent flight of owl, in this paper, the airfoil of owl's wing and the asymmetric sawtooth structure of the feather have been extracted and\u0000 reconstructed on the prototype wind turbine blades. The bionic airfoil blade and bionic coupling blade have been designed separately and compared with prototype blade. To obtain the asymmetric sawtooth structure with better acoustic performance, the sawtooth parameters are selected by orthogonal\u0000 test. The influence of airfoil and asymmetric sawtooth for acoustic performance of blade has been investigated with large eddy simulation method and Ffowcs Williams-Hawkings analogy method. The results show that the bionic coupling blade has a larger surface pressure difference compared with\u0000 the prototype blade and thus has better aerodynamic performance. The airfoil-structure coupling method can effectively reduce the aerodynamic noise of the blade without affecting the directivity of the acoustic, and optimized blade can reduce the noise by up to 8.42 dB. The blade coupling\u0000 airfoil has an inhibitory effect on intermediate and high frequency noise. After adding asymmetric sawtooth trailing edge, the noise in the low frequency and intermediate frequency range is further reduced.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44476860","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}
Liang Pu, Shengqi Zhang, Yiguang Pan, Jinglong Sun, Qiang Li
To reduce the noise caused by the flow of refrigerant during the defrost cycle and preserve the ambient sound level, this study concentrated on exploring the mechanism of noise generation in the gas–liquid separator based on visualization experiments. A transparent gas–liquid separator made of quartz glass, which was instead of the original one, was fabricated to observe the flow pattern of refrigerant in the gas–liquid separator, and the relationship between flow pattern and noise generation was investigated. The results showed that the noise is mainly generated during the defrost cycle. The sound power level has a drastic fluctuation when the liquid level of refrigerant in the gas–liquid separator is higher than the outlet of the evaporation tube during the defrost cycle. The reduction in noise is achieved by the redesigns that prevent the liquid level of refrigerant in the gas–liquid separator being higher than the outlet of the evaporation tube during the defrost cycle. Then, the noise level of original design and two redesigns was measured in a high precision semi-anechoicroom, respectively. The noise level of the refrigerator reduces from 30.2 dB(A) to 26.1 dB(A) and 24.4 dB(A) by increasing the volume of the gas–liquid separator for 87.1% and installing a ball valve respectively.
{"title":"Visualization study of two-phase flow and noise control in a multiple temperature refrigerator during the defrost cycle","authors":"Liang Pu, Shengqi Zhang, Yiguang Pan, Jinglong Sun, Qiang Li","doi":"10.3397/1/377014","DOIUrl":"https://doi.org/10.3397/1/377014","url":null,"abstract":"To reduce the noise caused by the flow of refrigerant during the defrost cycle and preserve the ambient sound level, this study concentrated on exploring the mechanism of noise generation in the gas–liquid separator based on visualization experiments. A transparent gas–liquid\u0000 separator made of quartz glass, which was instead of the original one, was fabricated to observe the flow pattern of refrigerant in the gas–liquid separator, and the relationship between flow pattern and noise generation was investigated. The results showed that the noise is mainly generated\u0000 during the defrost cycle. The sound power level has a drastic fluctuation when the liquid level of refrigerant in the gas–liquid separator is higher than the outlet of the evaporation tube during the defrost cycle. The reduction in noise is achieved by the redesigns that prevent the\u0000 liquid level of refrigerant in the gas–liquid separator being higher than the outlet of the evaporation tube during the defrost cycle. Then, the noise level of original design and two redesigns was measured in a high precision semi-anechoicroom, respectively. The noise level of the refrigerator\u0000 reduces from 30.2 dB(A) to 26.1 dB(A) and 24.4 dB(A) by increasing the volume of the gas–liquid separator for 87.1% and installing a ball valve respectively.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49254911","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}
S. Sakamoto, Y. Akiba, R. Iizuka, Shunsuke Watanabe, R. Kominami, Tetsushi Shintani
In general, the acoustic effective length of the open end of an air column is longer than its geometric length. Here, the effective increment of the geometric length of an air column is called the open-end correction length, which is an acoustically crucial issue. The purpose of this study is to experimentally clarify the open-end correction length for a slit shape with a narrow clearance. For this reason, the sound absorption coefficient was measured using a sample in which the neck of the Helmholtz resonator was shaped as a slit with a narrow clearance. Next, the open-end correction length (i.e., mass end correction length and resistive end correction length) was calculated backward by comparing the experimental and theoretical sound absorption curves. The resistive end correction increased as the slit width became narrower within the range of 0.5 mm or less for both the center slit and the slit near the wall, indicating a significant discrepancy between the theoretical equation and the estimated value. For the mass end correction, in the case the center slit, the estimated value is close to the theoretical value of in the slit width range from 0.3 mm to 1.0 mm. The results of this study may be useful in eliminating discrepancies in correction values for open-end correction in slits with narrow clearance.
{"title":"Experimental study on open-end correction of a Helmholtz resonator narrow slit neck","authors":"S. Sakamoto, Y. Akiba, R. Iizuka, Shunsuke Watanabe, R. Kominami, Tetsushi Shintani","doi":"10.3397/1/377011","DOIUrl":"https://doi.org/10.3397/1/377011","url":null,"abstract":"In general, the acoustic effective length of the open end of an air column is longer than its geometric length. Here, the effective increment of the geometric length of an air column is called the open-end correction length, which is an acoustically crucial issue. The purpose of this\u0000 study is to experimentally clarify the open-end correction length for a slit shape with a narrow clearance. For this reason, the sound absorption coefficient was measured using a sample in which the neck of the Helmholtz resonator was shaped as a slit with a narrow clearance. Next, the open-end\u0000 correction length (i.e., mass end correction length and resistive end correction length) was calculated backward by comparing the experimental and theoretical sound absorption curves. The resistive end correction increased as the slit width became narrower within the range of 0.5 mm or less\u0000 for both the center slit and the slit near the wall, indicating a significant discrepancy between the theoretical equation and the estimated value. For the mass end correction, in the case the center slit, the estimated value is close to the theoretical value of in the slit width range from\u0000 0.3 mm to 1.0 mm. The results of this study may be useful in eliminating discrepancies in correction values for open-end correction in slits with narrow clearance.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42977755","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}
One of the main concerns in the railway transportation is environmental pollutions caused by railway noise. The most important source of this noise is the rolling contact between wheel and rail, and therefore, prediction of the rolling noise is a key factor in the management and reduction of the noise. Despite numerous studies carried out on the rolling noise prediction in the available literature, the role of track components on the rolling noise has not been taken into account. That is, the power dissipation within the track superstructures has not been given sufficient consideration. This is addressed in this research by investigating the influences of the track components on the level of railway rolling noise. For this purpose, a new noise prediction approach is developed in this research using finite element method and the statistical energy analysis. This approach has an advantage of considering power dissipation along the track components compared with the previous approaches. The results obtained from the new approach were compared with field measurements carried out in this research. It is shown that the proposed finite element–statistical energy analysis approach is effective in accurate predictions of the ballasted railway track noise.
{"title":"Application of FE-SEA approach in investigation of track properties influences on railway rolling noise generation","authors":"J. Sadeghi, Parinus Vedadi, M. Vasheghani","doi":"10.3397/1/377016","DOIUrl":"https://doi.org/10.3397/1/377016","url":null,"abstract":"One of the main concerns in the railway transportation is environmental pollutions caused by railway noise. The most important source of this noise is the rolling contact between wheel and rail, and therefore, prediction of the rolling noise is a key factor in the management and reduction\u0000 of the noise. Despite numerous studies carried out on the rolling noise prediction in the available literature, the role of track components on the rolling noise has not been taken into account. That is, the power dissipation within the track superstructures has not been given sufficient consideration.\u0000 This is addressed in this research by investigating the influences of the track components on the level of railway rolling noise. For this purpose, a new noise prediction approach is developed in this research using finite element method and the statistical energy analysis. This approach has\u0000 an advantage of considering power dissipation along the track components compared with the previous approaches. The results obtained from the new approach were compared with field measurements carried out in this research. It is shown that the proposed finite element–statistical energy\u0000 analysis approach is effective in accurate predictions of the ballasted railway track noise.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47983593","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}
T. Satoh, Shuichi Sakamoto, Shunsuke Unai, Takunari Isobe, Kenata Iizuka, Katsuhiko Tasaki, I. Nitta, Tetsushi Shintani
In this study, the sound-absorption coefficients of a pin-holder structure consisting of a group of cylinders were estimated and compared with the experimental values for the case where sound waves are incident in the direction perpendicular to the cylinder's axis. To estimate the sound-absorption coefficient, the gap in the pinholder structure is divided into elements and approximated as being between two parallel planes, taking the exact shape of the divided elements into account. The characteristic impedance and propagation constant of the approximated clearances were calculated and treated as a one-dimensional transfer matrix. The transfer matrices for each element were used to calculate the sound-absorption coefficient. The calculated theoretical values were compared with the experimental ones. In the experiment, the samples were fabricated using a 3D printer, and the sound-absorption coefficient was measured using a two-microphone impedance-measurement tube. Although the experimental and theoretical values differed, they showed similar trends. We also found that the prediction error in the practical sound-absorption coefficient could be reduced by adjusting the diameter of the pins used in the calculation.
{"title":"Sound-absorption coefficient of a pin-holder structure for sound waves incident in the direction perpendicular to the cylinder's axis","authors":"T. Satoh, Shuichi Sakamoto, Shunsuke Unai, Takunari Isobe, Kenata Iizuka, Katsuhiko Tasaki, I. Nitta, Tetsushi Shintani","doi":"10.3397/1/377012","DOIUrl":"https://doi.org/10.3397/1/377012","url":null,"abstract":"In this study, the sound-absorption coefficients of a pin-holder structure consisting of a group of cylinders were estimated and compared with the experimental values for the case where sound waves are incident in the direction perpendicular to the cylinder's axis. To estimate the sound-absorption\u0000 coefficient, the gap in the pinholder structure is divided into elements and approximated as being between two parallel planes, taking the exact shape of the divided elements into account. The characteristic impedance and propagation constant of the approximated clearances were calculated\u0000 and treated as a one-dimensional transfer matrix. The transfer matrices for each element were used to calculate the sound-absorption coefficient. The calculated theoretical values were compared with the experimental ones. In the experiment, the samples were fabricated using a 3D printer, and\u0000 the sound-absorption coefficient was measured using a two-microphone impedance-measurement tube. Although the experimental and theoretical values differed, they showed similar trends. We also found that the prediction error in the practical sound-absorption coefficient could be reduced by\u0000 adjusting the diameter of the pins used in the calculation.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45870101","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}
Aero-engine is the most critical part of an aircraft. As its key component, the central bevel gear transmission system is always designed only considering the meshing vibration and ignoring structural characteristics of shafts and bearings, and comprehensive vibration characteristics is not well addressed. The transmission system may suffer severe vibration. To accurately study the dynamic characteristics of the system, a model of a central bevel gear transmission system is developed considering the effects of bevel gear mesh stiffness, shaft stiffness, bearing stiffness, and unbalance excitation in this paper. It has been validated by finite element software ANSYS. On this basis, the influence of variation of bearing stiffness and mesh stiffness on the natural characteristics of the central bevel gear transmission system is investigated. The influence of unbalance on the radial vibration and gear meshing force is studied by the analytical calculation method. A case study is carried out. The results show that variation of stiffness within a certain range will cause dramatic changes in the natural characteristics of the system. The unbalance of the driven bevel gear shaft has an effect on the radial vibration and meshing force of the system. The proposed model can reflect radial vibration characteristics, axial vibration characteristics, torsional vibration characteristics, and some coupled natural characteristics of the system. This research provides a theoretical basis to optimize dynamic performance and reduce the vibration of the system and will be helpful in designing the central bevel gear transmission system.
{"title":"Dynamic modeling of central bevel gear transmission system in aero-engine","authors":"Jia-You Liu, Hao Zhang, Jing-yu Zhai, Qingkai Han","doi":"10.3397/1/37704","DOIUrl":"https://doi.org/10.3397/1/37704","url":null,"abstract":"Aero-engine is the most critical part of an aircraft. As its key component, the central bevel gear transmission system is always designed only considering the meshing vibration and ignoring structural characteristics of shafts and bearings, and comprehensive vibration characteristics\u0000 is not well addressed. The transmission system may suffer severe vibration. To accurately study the dynamic characteristics of the system, a model of a central bevel gear transmission system is developed considering the effects of bevel gear mesh stiffness, shaft stiffness, bearing stiffness,\u0000 and unbalance excitation in this paper. It has been validated by finite element software ANSYS. On this basis, the influence of variation of bearing stiffness and mesh stiffness on the natural characteristics of the central bevel gear transmission system is investigated. The influence of unbalance\u0000 on the radial vibration and gear meshing force is studied by the analytical calculation method. A case study is carried out. The results show that variation of stiffness within a certain range will cause dramatic changes in the natural characteristics of the system. The unbalance of the driven\u0000 bevel gear shaft has an effect on the radial vibration and meshing force of the system. The proposed model can reflect radial vibration characteristics, axial vibration characteristics, torsional vibration characteristics, and some coupled natural characteristics of the system. This research\u0000 provides a theoretical basis to optimize dynamic performance and reduce the vibration of the system and will be helpful in designing the central bevel gear transmission system.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43531045","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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