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Calculation and Analysis of Acoustic Characteristics of Straight-Through Perforated Pipe Muffler Based on Multilayer Sound Absorbing Material
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作者 刘镕基 朱从云 +1 位作者 丁国芳 院蕾 《Journal of Donghua University(English Edition)》 CAS 2023年第5期506-514,共9页
Using the multi-physical field simulation software COMSOL,the acoustic characteristics of the multilayer sound absorbing material straight-through perforated pipe muffler are studied by the finite element method.The r... Using the multi-physical field simulation software COMSOL,the acoustic characteristics of the multilayer sound absorbing material straight-through perforated pipe muffler are studied by the finite element method.The results show that the finite element calculation of the multilayer sound absorbing material straight-through the perforated pipe muffler agrees well with the experimental measurement results.The reliability of the finite element method for studying the acoustic performance of the straight-through perforated pipe muffler with multilayer sound absorbing materials is shown.Furthermore,the influence of some structural parameters of porous sound absorbing material and micro-perforated plate on the acoustic performance of the multilayer sound absorbing material straight-through perforated pipe muffler is analyzed.The muffler based on multilayer sound absorbing material is different from the traditional muffler.After applying the multilayer sound absorbing material to the straight-through perforated pipe muffler,the transmission loss value greatly increases,which provides new ideas and directions for future research on the muffler. 展开更多
关键词 porous sound absorbing material perforated tube finite element method MUFFLER acoustic characteristics
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Acoustic characteristics of pulse detonation engine sound propagating in enclosed space 被引量:1
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作者 Yang Kang Ning Li +1 位作者 Chun-Sheng Weng Xiao-Long Huang 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第1期378-386,共9页
Acoustic characteristics of pulse detonation engine(PDE)sound propagating in enclosed space are numerically and experimentally investigated.The finite element software LS-DYNA is utilized to numerically simulate the P... Acoustic characteristics of pulse detonation engine(PDE)sound propagating in enclosed space are numerically and experimentally investigated.The finite element software LS-DYNA is utilized to numerically simulate the PDE sound propagating in enclosed space.Acoustic measurement systems are established for testing the PDE sound in enclosed space,and the time-frequency characteristics of PDE sound in enclosed space are reported in detail.The experimental results show that the sound waveform of PDE sound in enclosed space are quite different from those in open space,and the reflection and superposition of PDE sound on the walls of enclosed space results in the sound pressure oscillating obviously.It is found that the peak sound pressure level(PSPL)and overall sound pressure level(OASPL)of PDE sound in enclosed space are higher than those in open space and their difference increases with the rise of propagation distance.The results of the duration of PDE sound indicate that the A duration of PDE sound in enclosed space is higher than that in open space except at measuring points located at 2-m and 5-m while the B duration is higher at each of all measuring points.Results show that the enclosed space has a great influence on the acoustic characteristic of PDE sound.This research is helpful in performing PDE experiments in enclosed laboratories to prevent the PDE sound from affecting the safety of laboratory environment,equipment,and staffs. 展开更多
关键词 pulse detonation engine acoustics characteristics enclosed space
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Fine Sand and Clay Sediment Acoustic Properties of the Novel Sediment Sample from the Arabian Sea:Experimental Investigations and Biot−Stoll Model Validation
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作者 Shahabuddin SHAIKH HUANG Yi-wang +1 位作者 ZHANG Ze-chuan Habib Hussain ZUBERI 《China Ocean Engineering》 SCIE EI CSCD 2024年第1期169-180,共12页
The present study explores the physical and acoustic characteristics of fine sand and clay in novel seabed marine sediments from of Pakistan coastline of the Arabian Sea.The measured physical parameters included mean ... The present study explores the physical and acoustic characteristics of fine sand and clay in novel seabed marine sediments from of Pakistan coastline of the Arabian Sea.The measured physical parameters included mean grain size,mass density,bulk density,salinity,porosity,permeability,pore size and mineralogical composition.Acoustic properties,including sound speed and attenuation,in the high frequency range of 90-170 kHz were analyzed.A controlled laboratory setup with the acoustic transmission method and Fourier transform techniques was utilized to examine the sound propagation and absorption of novel seabed sediments.The standard deviation of mean sound speed in fresh water was 0.75 m/s,and attenuation was observed in the range of 0.43 to 0.61 dB/m.The mean sound velocity in sand and clay varied from 1706 to 1709 m/s and 1602 to 1608 m/s,respectively.Corresponding average attenuation was observed at 80 to 93 dB/m in sandy sediments and from 31.8 to 38.6 dB/m in clayey sediments.Sound velocity variation within sandy sediment is low,consistent with expected results,and smaller than the predicted uncertainty.However,clay sediment exhibited a positive linear correlation and low sound speed variation.Attenuation increased linearly with frequency for both sediments.Finally,the laboratory results were validated by using the Biot−Stoll model.The dispersion of sound speed in sandy and clayey sediments was consistent with the predictions of the Biot−Stoll model.Measured attenuation aligned more with Biot−Stoll model predictions due to improved permeability,tortuosity and pore size parameter fitting. 展开更多
关键词 physical and acoustic characteristics marine sediments sound speed ATTENUATION Biot−Stoll model
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Mechanical behavior of 2G NPR bolt anchored rock samples under static disturbance loading
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作者 WANG Jiong JIANG Jian +4 位作者 WANG Siyu CHANG Yiwen LIU Peng HE Manchao CHENG Shuang 《Journal of Mountain Science》 SCIE CSCD 2024年第7期2494-2516,共23页
The deep mining of coal resources is accompanied by severe environmental challenges and various potential engineering hazards.The implementation of NPR(negative Poisson's ratio)bolts are capable of controlling lar... The deep mining of coal resources is accompanied by severe environmental challenges and various potential engineering hazards.The implementation of NPR(negative Poisson's ratio)bolts are capable of controlling large deformations in the surrounding rock effectively.This paper focuses on studying the mechanical properties of the NPR bolt under static disturbance load.The deep nonlinear mechanical experimental system was used to study the mechanical behavior of rock samples with different anchored types(unanchored/PR anchored/2G NPR anchored)under static disturbance load.The whole process of rock samples was taken by high-speed camera to obtain the real-time failure characteristics under static disturbance load.At the same time,the acoustic emission signal was collected to obtain the key characteristic parameters of acoustic emission such as acoustic emission count,energy,and frequency.The deformation at the failure of the samples was calculated and analyzed by digital speckle software.The findings indicate that the failure mode of rock is influenced by different types of anchoring.The peak failure strength of 2G NPR bolt anchored rock samples exhibits an increase of 6.5%when compared to the unanchored rock samples.The cumulative count and cumulative energy of acoustic emission exhibit a decrease of 62.16%and 62.90%,respectively.The maximum deformation of bearing capacity exhibits an increase of 59.27%,while the failure time demonstrates a delay of 42.86%.The peak failure strength of the 2G NPR bolt anchored ones under static disturbance load exhibits an increase of 5.94%when compared to the rock anchored by PR(Poisson's ratio)bolt.The cumulative count and cumulative energy of acoustic emission exhibit a decrease of 47.16%and 43.86%,respectively.The maximum deformation of the bearing capacity exhibits an increase of 50.43%,and the failure time demonstrates a delay of 32%.After anchoring by 2G NPR bolt,anchoring support effectively reduces the risk of damage caused by static disturbance load.These results demonstrate that the support effect of 2G NPR bolt materials surpasses that of PR bolt. 展开更多
关键词 Anchored rock samples Static disturbance load Acoustic emission characteristics Digital speckle Negative Poisson's ratio
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Abaca Fiber as a Potential Reinforcer for Acoustic Absorption Material at Middle-High Frequencies
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作者 Susilo Indrawati Lila Yuwana +2 位作者 Suyatno Mochamad Zainuri Darminto 《Journal of Renewable Materials》 EI CAS 2024年第5期909-921,共13页
Recently,abacafibers have become the focus of specialized research due to their intriguing characteristics,with their outstanding mechanical properties being a particularly notable.In the conducted study,the abacafibers... Recently,abacafibers have become the focus of specialized research due to their intriguing characteristics,with their outstanding mechanical properties being a particularly notable.In the conducted study,the abacafibers underwent a preliminary treatment process involving an alkaline solution,which was composed of 0.5%sodium hydroxide(NaOH)and 50%acetic acid(CH3COOH).This process entailed immersing eachfiber in the solution for a period of one hour.This treatment led to a 52.36%reduction in lignin content compared to the levels before treatment,resulting in a dramatic decrease in the full width at half maximum(FWHM)in the XRD spectra from 1.13 to 0.13.This change indicates that thefibers became more crystalline following the treatment.The abacafibers were also characterized using BET(Brunauer Emmett Teller)measurements,which revealed that the aver-age pore length ranged from 33–49 nm and the surface area was between 13–28 m^(2)·g^(-1).The morphology of the abacafiber after alkali an hydrolisis treatment(AFAH)appeared rougher and more uniform.DMA measurements revealed a significant rise in the storage modulus of the singlefiber post-treatment,with dependencies on both frequency and temperature.AFAH exhibited an optimal absorption coefficient ofα=0.9 for frequencies above 2500 Hz.The combined effect of alkalization and hydrolyzation treatments,while resulting in an enhancement in the mechanical properties of thefibers,also reduced high-intensity noise produced by sources such as machin-ery,aircraft takeoffs and landings,etc.,across a broader working frequency range. 展开更多
关键词 Abacafiber ALKALIZATION mechanical property acoustic characteristics middle frequency
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Acoustic characteristics of pulse detonation engine with ellipsoidal reflector 被引量:4
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作者 Yang Kang Ning Li +1 位作者 Chun-Sheng Weng Chuan-Wei Wang 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第10期413-423,共11页
Acoustic characteristics of a pulse detonation engine(PDE) with and without an ellipsoidal reflector are numerically and experimentally investigated. A two-dimensional(2 D) non-splitting unstructured triangular me... Acoustic characteristics of a pulse detonation engine(PDE) with and without an ellipsoidal reflector are numerically and experimentally investigated. A two-dimensional(2 D) non-splitting unstructured triangular mesh Euler solver based on the space-time conservation element and solution element(CE/SE) method is employed to simulate the flow field of a PDE.The numerical results clearly demonstrate the external flow field of the PDE. The effect of an ellipsoidal reflector on the flow field characteristic near the PDE exit is investigated. The formation process of reflected shock wave and reflected jet shock are reported in detail. An acoustic measurement system is established for the PDE acoustic testing. The experimental results show that the ellipsoidal reflector changes the sound waveform and directivity of PDE sound. The reflected shock wave and reflected jet shock result in two more positive pressure peaks in the sound waveform. The ellipsoidal reflector changes the directivity of PDE sound from 20 to 0. It is found that the peak sound pressure level(PSPL) and overall sound pressure level(OASPL) each obtain an increment when the PDE is installed with a reflector. The maximum relative increase ratio of PSPL and OASPL are obtained at the focus point F2, whose values are 6.1% and 6.84% respectively. The results of the duration of the PDE sound indicate that the reflecting and focusing wave generated by the reflector result in the increment of A duration and B duration before and near focus point F2. Results show that the ellipsoidal reflector has a great influence on the acoustic characteristic of PDE sound. The research is helpful for understanding the influence of an ellipsoidal reflector on the formation and propagation process of PDE sound. 展开更多
关键词 pulse detonation engine ellipsoidal reflector acoustic characteristics experiments and simulations
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Acoustic characteristics of eight common Chinese anurans during the breeding season 被引量:3
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作者 Yi-Lin ZHOU Xia QIU +5 位作者 Xiao-Bin FANG Lu-Yi YANG Yi ZHAO Teng FANG Wei-Hong ZHENG Jin-Song LIU 《Zoological Research》 CAS CSCD 北大核心 2014年第1期42-50,共9页
Anurans often have species-specific vocalizations. To quantify and compare the characteristics of anuran calls in Gutianshan National Nature Reserve, Zhejiang Province, we recorded the advertisement calls of eight spe... Anurans often have species-specific vocalizations. To quantify and compare the characteristics of anuran calls in Gutianshan National Nature Reserve, Zhejiang Province, we recorded the advertisement calls of eight species belonging to four families (Ranidae, Microhylidae, Megophryidae and Bufonidae) from June to September 2012 using Sony ICD-FX8 IC recorders. All recordings were analyzed using the "Praat" software. Five acoustics parameters were measured, including temporal traits (call duration, number of notes or pulse number/call) and spectral traits (fundamental frequency, the first three formants and dominant frequency). The characteristic parameters of Microhyla ornate and Fejervarya limnocharis calls were different as were the calls of some populations of the same species recorded in different regions. The advertisement calls of the eight species were specific. Our study has provided a useful reference for identifying the calls of some common Chinese anurans. 展开更多
关键词 ANURANS Advertisement calls Acoustic characteristics
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Acoustic characteristics of bubble bursting at the surface of a high-viscosity liquid 被引量:2
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作者 刘晓波 张建润 李普 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第5期348-352,共5页
An acoustic pressure model of bubble bursting is proposed.An experiment studying the acoustic characteristics of the bursting bubble at the surface of a high-viscosity liquid is reported.It is found that the sudden bu... An acoustic pressure model of bubble bursting is proposed.An experiment studying the acoustic characteristics of the bursting bubble at the surface of a high-viscosity liquid is reported.It is found that the sudden bursting of a bubble at the high-viscosity liquid surface generates N-shape wave at first,then it transforms into a jet wave.The fundamental frequency of the acoustic signal caused by the bursting bubble decreases linearly as the bubble size increases.The results of the investigation can be used to understand the acoustic characteristics of bubble bursting. 展开更多
关键词 bubble bursting acoustic characteristics high-viscosity liquid
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Acoustic Characteristics Analysis of Industrial Premises with Process Equipment 被引量:1
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作者 I. Tsukernikov A. Antonov +2 位作者 V. Ledenev I. Shubin T. Nevenchannaya 《Journal of Applied Mathematics and Physics》 2016年第2期206-210,共5页
Process equipment placing in industrial premises leads to essential change of room acoustic characteristics: mean length of sound rays’ free runs, reverberation time and mean absorption factor in a room. The changes ... Process equipment placing in industrial premises leads to essential change of room acoustic characteristics: mean length of sound rays’ free runs, reverberation time and mean absorption factor in a room. The changes influence distribution of the reflected sound energy in premise volume. Failure to take account of the given circumstance results in errors at definition of sound pressure levels and an estimation of efficiency of building-acoustic measures of noise abatement. In the paper the results of computer modeling of acoustic processes in premises with the process equipment are considered and influence of the equipment on a sound absorption indoors is analyzed. The computer simulation is carried out on the basis of the ray tracing method with taking into account rays’ energy distribution in a room. It is shown that such approach allows determining objectively the integral acoustic characteristics of industrial premises, takes into account influencing to them the room parameters, the presence and scattering characteristics of the equipment and makes more accurate the equations putting into engineering practice. 展开更多
关键词 Room Acoustic characteristics Industrial Premise Process Equipment
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Experimental study of the influence of annular nozzle on acoustic characteristics of detonation sound wave generated by pulse detonation engine
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作者 Yang Kang Ning Li +1 位作者 Xiao-Long Huang Chun-Sheng Weng 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第10期436-443,共8页
Acoustic characteristics of the detonation sound wave generated by a pulse detonation engine with an annular nozzle,including peak sound pressure, directivity, and A duration, are experimentally investigated while uti... Acoustic characteristics of the detonation sound wave generated by a pulse detonation engine with an annular nozzle,including peak sound pressure, directivity, and A duration, are experimentally investigated while utilizing gasoline as fuel and oxygen-enriched air as oxidizer. Three annular nozzle geometries are evaluated by varying the ratio of inner cone diameter to detonation tube exit diameter from 0.36 to 0.68. The experimental results show that the annular nozzles have a significant effect on the acoustic characteristics of the detonation sound wave. The annular nozzles can amplify the peak sound pressure of the detonation sound wave at 90° while reducing it at 0° and 30°. The directivity angle of the detonation sound wave is changed by annular nozzles from 30° to 90°. The A duration of the detonation sound wave at 90° is also increased by the annular nozzles. These changes indicate that the annular nozzles have an important influence on the acoustic energy distribution of the detonation sound wave, which amplify the acoustic energy in a direction perpendicular to the tube axis and weaken it along the direction of the tube axis. 展开更多
关键词 pulse detonation engine annular nozzle detonation sound wave acoustic characteristics
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Propagation and Attenuation Characteristics of Diesel Particulate Filter
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作者 高文志 宋崇林 +1 位作者 刘建国 关顺吉 《Transactions of Tianjin University》 EI CAS 2005年第4期278-282,共5页
Diesel particulate filter (DPF) is an important factor which influences the sound from exhaust system of an engine. In order to understand the propagation law of sound wave and predict the insertion loss in DPF, based... Diesel particulate filter (DPF) is an important factor which influences the sound from exhaust system of an engine. In order to understand the propagation law of sound wave and predict the insertion loss in DPF, based on the general aero-dynamic equations and Darcy′s law, an acoustic property calculation model of DPF is constructed. Propagation and attenuation characteristics of the forward and backward propagating acoustic waves in the close and open pipe of the filter are investigated. The theoretical model is combined with experiment to investigate sound attenuation property of DPF. The insertion loss obtained from the experiment is compared with that computed for a DPF. The results from the experiment and theoretical calculation agree well. 展开更多
关键词 diesel particulate filter acoustic characteristics insertion loss propagation constant
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Comparison of Acoustic Characteristics of Gnathotrichus materiarius and Gnathotrichus sulcatus
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作者 Pan Jie Liu Xiang +4 位作者 Shao Peize Yan Liusong Qin Guoxun An Yulin Wen Junbao 《Plant Diseases and Pests》 CAS 2014年第5期33-37,共5页
As an emerging technology for pest monitoring, sound detection technology has the unique advantages in the field of plant quarantine. Experts at home and abroad have done lots of researches on sound detection technolo... As an emerging technology for pest monitoring, sound detection technology has the unique advantages in the field of plant quarantine. Experts at home and abroad have done lots of researches on sound detection technology for trunk borers, and achieved good results. The audible signals of adult Gnathotrichus mate- riarius and G. sulcatus were detected using sound detection method. It was concluded that the feeding and crawling acoustic signals of G. materiarius and G. sulca- tun were significantly different, and the acoustic signals were greatly different even in the same species. In addition, the signal pulse duration and dominant frequen- cy were significantly different. Therefore, it is feasible to monitor trunk borers using sound detection technology. 展开更多
关键词 Gnathotrichus materiarius Gnathotrichus sulcatus FEEDING CRAWLING Acoustic characteristics
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Preliminary Study on Acoustic Characteristics of Ips grandicollis Larvae
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作者 Jie PAN Fei LU +3 位作者 Yijing ZHOU Guang YANG Yulin AN Junbao WEN 《Plant Diseases and Pests》 CAS 2022年第4期7-10,共4页
[Objectives]The paper was to analyze the acoustic characteristics of Ips grandicollis larvae by pest acoustic detection technology,and to provide some reference for quarantine identification of pest larvae at ports.[M... [Objectives]The paper was to analyze the acoustic characteristics of Ips grandicollis larvae by pest acoustic detection technology,and to provide some reference for quarantine identification of pest larvae at ports.[Methods]The trial was performed in a self-invented insect sound recording container with good sound insulation effect.I.grandicollis larvae were placed separately on split P.ponderosa logs to observe and record the activities of larvae.AED-2010 was used for signal acquisition and SP-1 probe was used to collect signals at a distance of 5 cm from the larvae.The activity signals of larvae were intercepted,and the signal de-noising was further processed by Goldwave software.Finally,the acoustic signals were carried out correlation analysis by using MATLAB toolbox.[Results]I.grandicollis larvae had more regular feeding acoustic signal characteristics than crawling acoustic signal characteristics,and the two types of acoustic signal characteristics were quite different.The duration of feeding acoustic signal pulse of I.grandicollis larvae was 50-85 ms,the frequency was less than 1 KHz,and the signal frequency was mainly distributed in the range of 510.00-620.20 Hz.There was no obvious law in time domain features of larval crawling acoustic signals and the signal frequency was low,which was below 0.6 KHz and was mainly distributed in the range of 258.00-530.00 Hz.[Conclusions]It is feasible to carry out quarantine identification of I.grandicollis larvae by using feeding acoustic signals.It is suggested to select the feeding acoustic signals with obvious characteristics in the sound monitoring and identification of pests. 展开更多
关键词 Sound detection Acoustic characteristics Ips grandicollis LARVAE Preliminary analysis
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Spatial differentiation and dynamic mechanism of micro-geomorphology based on acoustic spectrum data of the Huanghe(Yellow)River Delta
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作者 Ping LI Yongde JIN +1 位作者 Wei GAO Xiaolong ZHAO 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2023年第6期2077-2089,共13页
Submarine micro-geomorphology is a geo-morphological type occurring in shallow and surface areas of seabed.The combined relationships and distribution of the micro-geomorphology indirectly reflect coupling relationshi... Submarine micro-geomorphology is a geo-morphological type occurring in shallow and surface areas of seabed.The combined relationships and distribution of the micro-geomorphology indirectly reflect coupling relationships among the sediment deposition,dynamic environment,and geomorphologic evolution.Spatial differentiation and dynamic changes in micro-geomorphology were studied based on acoustic data interpretation from a wide range(3200 km^(2))of the Huanghe(Yellow)River delta(HRD).The combination of the sub-bottom profiler and the side-scan sonar methods allowed for the identification of submarine shallow micro-geomorphologic types,as well as their scale and spatial distributions.There were seven typical micro-geomorphologic features in the shallow and surface areas of the HRD,including buried ancient channels,stratigraphic disturbances,scour troughs,sand waves,pits,erosional remnants,and sand spots.The coupling and superposition of the sediment,sediment characteristics,seabed scouring and silting,and hydrodynamic conditions of the Huanghe River had combined effects on the patterns of micro-geomorphologic types,characteristics,and ranges.From the perspective of acoustic profile interpretations,the scale,range,and spatial locations of the microgeomorphology in the HRD revealed seasonal variation characteristics,and the spatial distributions displayed significant regional differentiation characteristics.In addition,strong stratigraphic disturbances and areas with densely distributed buried ancient channels reflected the activity and instability of the submarine shallow strata.Through the interpretation of the sub-bottom profile detection data,the diversion processes of the flow paths in the lower reaches of the Huanghe River were obtained for a certain historical period in the coastal waters of the HRD.This study further clarified the relationships between the micro-geomorphologic features and spatial combinations,which is important for research on micro-geomorphologic features and their dynamic mechanisms. 展开更多
关键词 Huanghe(Yellow)River delta(HRD) micro-geomorphology acoustic reflection characteristics spatial differentiation dynamic mechanisms
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PREDICTION OF ACOUSTIC PERFORMANCE IN EXPANSION CHAMBER MUFFLERS WITH MEAN FLOW BY FINITE ELEMENT METHOD 被引量:4
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作者 Liu YadongLi CongxinRuan XueyuNational Die & Mold CAD EngineeringResearch Center,Shanghai Jiaotong University,Shanghai 200030, China 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2003年第3期292-295,304,共5页
The equation of wave propagation in a circular chamber with mean flow is obtained. Computational solution based on finite element method is employed to determine the transmission loss of expansive chamber. The effect ... The equation of wave propagation in a circular chamber with mean flow is obtained. Computational solution based on finite element method is employed to determine the transmission loss of expansive chamber. The effect of the mean flow and geometry (length of expansion chamber and expansion ratio)on acoustic attenuation performance is discussed, the predicted values of transmission loss of expansion chamber without and with mean flow are compared with those reported in the literature and they agree well. The accuracy of the prediction of transmission loss implies that finite element approximations are applicable to a lot of practical applications. 展开更多
关键词 Wave equation Finite element method Exhaust mufflers Acoustic characteristics
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Numerical investigation of the interaction of the turbulent dual-jet and acoustic propagation 被引量:3
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作者 Yi-Ming Li Bao-Kuan Li +1 位作者 Feng-Sheng Qi Xi-Chun Wang 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第2期294-304,共11页
In order to study the interaction between two independent jets, a three-dimensional(3D) transient mathematical model is developed to investigate the flow field and acoustic properties of the two-stream jets. The res... In order to study the interaction between two independent jets, a three-dimensional(3D) transient mathematical model is developed to investigate the flow field and acoustic properties of the two-stream jets. The results are compared with those of the single-stream jet at Mach number 0.9 and Reynolds number 3600. The large eddy simulation(LES) with dynamic Smagorinsky sub-grid scale(SGS) approach is used to simulate the turbulent jet flow structure. The acoustic field is evaluated by the Ffowcs Williams–Hawkings(FW-H) integral equation. Considering the compressibility of high-speed gas jets, the density-based explicit formulation is adopted to solve the governing equations. Meanwhile, the viscosity is approximated by using the Sutherland kinetic theory. The predicted flow characteristics as well as the acoustic properties show that they are in good agreement with the existing experimental and numerical results under the same flow conditions available in the literature. The results indicate that the merging phenomenon of the dual-jet is triggered by the deflection mechanism of the Coanda effect, which sequentially introduces additional complexity and instability of flow structure. One of the main factors affecting the dual-jet merging is the aperture ratio, which has a direct influence on the potential core and surrounding flow fluctuation. The analysis on the noise pollution reveals that the potential core plays a fundamental role in noise emission while the additional mixing noise makes less contribution than the single jet noise. The overall sound pressure level(OASPL) profiles have a directive property, suggesting an approximate 25° deflection from the streamwise direction, however, shifting toward lateral direction of about 10° to 15° in the dual-jet. The conclusion obtained in this study can provide valuable data to guide the development of manufacturing-green technology in the multi-jet applications. 展开更多
关键词 dual-jet jet entrainment acoustic characteristic Coanda effect
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Effect of Fiber Diameter and Air Gap on Acoustic Performance of Nanofibrous Membrane
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作者 Merve Ktiqukali Ozttirk Banu Nergis +1 位作者 Cevza Candan Klara Kalinova 《Journal of Chemistry and Chemical Engineering》 2015年第1期45-50,共6页
The absorption of sound in the low frequency range is problematic with fibrous materials made up of coarser fibers. In that case, highly efficient sound absorption materials from much finer fibers must be developed. A... The absorption of sound in the low frequency range is problematic with fibrous materials made up of coarser fibers. In that case, highly efficient sound absorption materials from much finer fibers must be developed. Although studies on the acoustic properties of conventional textile materials started in the nineties, analysis of the acoustic properties of the electrospun nanofibrous membranes is a novel subject. Nanofibrous membranes can improve acoustic insulation products by increasing the sound absorption coefficient, reducing material thickness, and decreasing material weight offering a competitive advantage. The purpose of this study is to analyze the effect of fiber diameter on the acoustic behavior of nanofibrous membranes. 展开更多
关键词 Etectrospun nanofibrous membrane acoustic characteristic fiber diameter.
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Synthesized acoustic signal characteristics of net-cage-cultured Large yellow croaker,Pseudosciaena crocea 被引量:1
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作者 WEI Chong ZHANG Yu +1 位作者 ZHANG Sai XU Xiaohui 《Chinese Journal of Acoustics》 2014年第1期54-64,共11页
This study performs the quantitative analysis and comparison to acoustic signal characteristics of Large yellow croaker (Pseudosciaena crocea) at two different ages. The sounds were recorded from the fishes in a net... This study performs the quantitative analysis and comparison to acoustic signal characteristics of Large yellow croaker (Pseudosciaena crocea) at two different ages. The sounds were recorded from the fishes in a net-cage. Two exponential oscillation functions are built to fit the acoustic signal of the fishes. The signal characteristic of the oscillation frequency and attenuation coefficient was described quantitatively. Simulation curves of the function could fit well acoustic signals. Both the average oscillation frequency and attenuation coefficient of the fitted signals from the 13-15-month-old fishes are lower than those from the 7-8-month-old fishes. The results suggest that the oscillation frdquency and attenuation coefficient of the acoustic signal flmction may be relevant to the physical process of sound production and age characteristics of Large yellow croaker. This study may be valuable for the acoustic application to the artificial culture of the species. 展开更多
关键词 Synthesized acoustic signal characteristics of net-cage-cultured Large yellow croaker Pseudosciaena crocea cage net
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Acoustic characteristics of stop consonants in fluent reading Chinese Putonghua speech of adult stutterers 被引量:1
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作者 FENG Yongqiang YAN Qian +4 位作者 GAO Xinglong PAN Fuping XING Lili LIN Chunlan PAN Jielin 《Chinese Journal of Acoustics》 2013年第3期298-308,共11页
This study investigated whether adults who stutter and normal adult speakers differ in the production of stop consonants in fluent reading Chinese Putonghua speech.Voice onset time(VOT) was measured and the spectral... This study investigated whether adults who stutter and normal adult speakers differ in the production of stop consonants in fluent reading Chinese Putonghua speech.Voice onset time(VOT) was measured and the spectral moments at the stop burst were calculated for the stutterers(both before and after the speech therapy) and also for the nonstutterers. The statistical results showed that there were no significant differences in VOT between the nonstutterers and stutterers either prior to or after therapy,although the mean VOT of the stutterers was slightly greater than that of the nonstutterers.The results also indicated that both the obstruction place and the subsequent syllabic final exhibited an influence to a greater extent on VOT for the stutterers.In the spectral domain,the spectral mean of the stuttering participants before therapy was significantly different from that of the normal participants, whereas the group difference became insignificant after the therapy session.The smaller spectral mean for the stutterers might be interpreted as a more posterior occlusion in the oral cavity when producing alveolars and velars.In addition,productions of the stutterers scattered with a wider range in the space of spectral moments.Furthermore,the smaller main effect of syllabic finals on the mean spectral frequency of the burst suggested that the stutterers exhibited weaker anticipatory coarticulation than the nonstutterers. 展开更多
关键词 Acoustic characteristics of stop consonants in fluent reading Chinese Putonghua speech of adult stutterers VOT
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Acoustic characteristics of bi-directional turbines for thermoacoustic generators
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作者 Dongdong LIU Yanyan CHEN +1 位作者 Wei DAI Ercang LUO 《Frontiers in Energy》 SCIE CSCD 2022年第6期1027-1036,共10页
Bi-directional turbines combined with rotary motors may be a feasible option for developing high power thermoacoustic generators with low cost.A general expression for the acoustic characteristics of the bidirectional... Bi-directional turbines combined with rotary motors may be a feasible option for developing high power thermoacoustic generators with low cost.A general expression for the acoustic characteristics of the bidirectional turbine was proposed based on theoretical derivation,which was validated by computational fluid dynamics modeling of an impulse turbine with fixed guide vanes.The structure of the turbine was optimized primarily using steady flow with an efficiency of near 70%(the shaft power divided by the total energy consumed by the turbine).The turbine in the oscillating flow was treated in a lumped-parameter model to extract the acoustic impedance characteristics from the simulation results.The key acoustic impedance characteristic of the turbine was the resistance and inertance due to complex flow condition in the turbine,whereas the capacitance was treated as an adiabatic case because of the large-scale flow channel relative to the heat penetration depth.Correlations for the impedance were obtained from both theoretical predictions and numerical fittings.The good fit of the correlations shows that these characteristics are valid for describing the bi-directional turbine,providing the basis for optimization of the coupling between the thermoacoustic engine and the turbine using quasi-one-dimensional theory in the frequency domain. 展开更多
关键词 thermoacoustic power generator acoustic characteristics bi-directional impulse turbine energy conversion
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