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Study on Acoustic performance for Diatom Frustule with Nanoporous Structure

Journal of Bionic Engineering 2023年第4期20卷 1656-1669页

作者： Fanming Meng Yong Zheng Hongxia Wang Lin Chen College of Mechanical Engineering Hubei University of Automotive TechnologyShiyan442002China State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing400044China

The Acoustic performance for the nanoporous frustule of the diatom is studied based on the computational fluid dynamics theory and acoustic theory involved.Representative Coscinodiscus sp.frustule is observed through the scanning electron microscope and modeled by the commercial software Solidworks.Further,the Acoustic performance for the Coscinodiscus sp.frustule is studied at the varied depth,diameter or interval of the pore,as well as the film thickness of the fluid surrounding the Coscinodiscus sp.frustule.The numerical results show that,when the upper and lower pore diameters are separately 200 and 300 nm,the upper and lower pore depths are separately 200 and 250 nm,and both the pore interval and fluid film thickness are 500 nm,the elaborate nanoporous structure of Coscinodiscus sp.frustule can lower its acoustic power level by 17.49%,compared with that without porous structure.Meanwhile,the double-layer pore of Coscinodiscus sp.frustule can decrease its acoustic power level by 12.69%,compared with its single-layer pore structures.

关键词： Acoustic performance Nanoporous structure Diatom Computational fluid dynamics

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FEM Analysis on Acoustic performance of Wall Flow Diesel Particulate Filters

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 701-706页

作者： GAO Wenzhi FENG Liming State Key Laboratory of Engines Tianjin University Tianjin 300072 China

Diesel powered vehicles, in compliance with the more strict exhaust emission standards such as Euro V, is likely to require a diesel particulate filter （DPF）. A DPF used on a vehicle will affect the acoustic emission of the diesel engine, so it is important to investigate the sound propagation rule in DPF and further to propose the optimum DPF design. However, due to the geometrical complexity of the DPF, the traditional analysis method, such as analytical method, can not assess the Acoustic performance of DPF accurately in medium and high frequency band. In this paper, a combined approach of finite element analysis and viscosity correction is proposed to predict Acoustic performance of DPF. A simplified model of the full DPF is established and is used to analyze the sound propagation characteristic of the DPF. The distribution of the sound pressure and velocity, the transmission matrix of the DPF are obtained using the finite element method. In addition, the method of the viscosity correction is used in the transmission matrix of the DPF to evaluate the Acoustic performance of DPF. Based on the FEM computation and the viscosity correction, the transmission losses under the rated load and idle condition of a diesel engine are calculated. The calculation results show that DPF can effectively attenuate exhaust noise, and sound attenuation increase with the rise of the frequency. Sound attenuation is better under rated condition than idle condition of diesel engine, particularly in frequency above 1 000 Hz.

关键词： diesel particulate filter Acoustic performance FEM model viscosity correction

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Research on the Acoustic performance with unsteady excitation based LBM method

Research on the acoustic performance with unsteady excitatio...

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第十一届南方计算力学学术会议（SCCM-11）

作者： Xue Yongfei Wang Hong Liu Zhimig Xie Junlong Henan University of Technology Huazhong University of Science and Technology

In this paper, a two-dimensional lattice jet model is obtained, based on the Lattice Boltzmann Method(LBM) of D2G9 model, using the non-equilibrium extrapolation boundary conditions, considering the periodic excitation conditions momentum thickness at the entry in non-steady state, adopting the Lagrange density of macro-discrete system to present the sound field. under the conditions of different incentives under the low Mach number flow field and sound field, given the results of characteristic line, and CFD, finite element calculations in good agreement with the literature.

关键词： lattice Boltzmann method unsteady excitation Lagrange density Acoustic performance

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Predicting the Reflection Coefficient of a Viscoelastic Coating Containing a Cylindrical Cavity Based on an Artificial Neural Network Model

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Computer Modeling in Engineering & Sciences 2022年第2期130卷 1149-1170页

作者： Yiping Sun Qiang Bai Xuefeng Zhao Meng Tao School of Mechanical Engineering Guizhou UniversityGuiyang550025China Aviation Academy Guizhou Open UniversityGuiyang550003China

A cavity viscoelastic structure has a good sound absorption performance and is often used as a reflective baffle or sound absorption cover in underwater acoustic structures.The Acoustic performance field has become a key research direction worldwide.Because of the time-consuming shortcomings of the traditional numerical analysis method and the high cost of the experimental method for measuring the reflection coefficient to evaluate the Acoustic performance of coatings,this innovative study predicted the reflection coefficient of a viscoelastic coating containing a cylindrical cavity based on an artificial neural network(ANN).First,themapping relationship between the input characteristics and reflection coefficient was analysed.When the elastic modulus and loss factor value were smaller,the characteristics of the reflection coefficient curve were more complicated.These key parameters affected the Acoustic performance of the viscoelastic coating.Second,a dataset of the Acoustic performance of the viscoelastic coating containing a cylindrical cavity was generated based on the finite elementmethod(FEM),which avoided a large number of repeated experiments.The minmax normalization method was used to preprocess the input characteristics of the viscoelastic coating,and the reflection coefficient was used as the dataset label.The grid search method was used to fine-tune the ANNparameters,and the prediction error was studied based on a 10-fold cross-validation.Finally,the error distributions were analysed.The average root means square error(RMSE)and the mean absolute percentage error(MAPE)predicted by the improved ANN model were 0.298%and 1.711%,respectively,and the Pearson correlation coefficient(PCC)was 0.995,indicating that the improved ANN model accurately predicted the Acoustic performance of the viscoelastic coating containing a cylindrical cavity.In practical engineering applications,by expanding the database of the material range,cavity size and backing of the coating,the reflection coefficient of more sound-absorb

关键词： Coating Acoustic performance artificial neural network predicting

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acoustic improvement on two lecture auditoria： Simulation and experiment

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Frontiers of Architectural Research 2017年第1期6卷 1-16页

作者： Soha Eldakdoky Ahmed Elkhateeb Department of Architecture Faculty of Engineering Helwan University Egypt Department of Architecture Faculty of Engineering Ain Shams University Egypt

Based on the commonly used indicators for speech intelligibility, this work acoustically evaluates the two largest auditoria in the Faculty of Engineering, Helwan University, Cairo, Egypt, using experimental and digital simulation techniques. Design treatments were also suggested to improve the Acoustic performance of the auditoria, where the impact of these treatments was checked using the simutation as well. The models that were analysed using the CATT-software were first validated utilizing the results of the fietd work in the unoccupied rooms. The results showed that the acoustic quality of the two auditoria are far from the optimal conditions due to their improper acoustic characteristics and the high noise revers as weft. The results of improvement proposals showed that altering the ceiling shape and adding efficient absorptive materials to the rear surfaces successfully reduced the excessive reverberation time to the optimal values, increased the earty reflections and eliminated the shadow zones. In addition, decreasing the noise Levels by 20 dB due to improving the window insulation noticeably improved the speech intelligibitity at all receivers.

关键词： Acoustic performance Speech intelligibility Reverberation time Background noise lever Lecture auditoria

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Effects of Inlet/Outlet Ducts on acoustic Attenuation Characteristics of Circular Expansion Chambers

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Journal of Beijing Institute of Technology 2006年第3期15卷 253-257页

作者：张宏波葛蕴珊季振林张文平宋艳冗韩秀坤张学敏 School of Mechanical and Vehicular Engineering Beijing Institute of TechnologyBeijing 100081 China School of Power and Nuclear Engineering Harbin Engineering University Harbin 150001 China

The effect of coaxial, offset and extended inlet/outlet on the acoustic attenuation characteristics of circular expansion chambers are studied by the three-dimensional finite dement method. The numerical results of transmission loss are compared with experiment results to verify the necessary of using three-dimensional methods. Maps of acoustic pressure level distribution inside of chambers and inlet/outlet ducts are given at a frequency to demonstrate the difference of acoustic wave propagation behavior caused by locations of inlet/outlet ducts. For the chambers of the same length, the chamber with extended inlet/outlet duct has higher attenuation ability than coaxial and offset inlet/outlet duct over middle frequencies.

关键词： three-dimensional Acoustic performance chamber

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