Research on near Field Acoustic Characteristic of a Compound Structure with Plate & Cylindrical Hull Subjected to Sound Excitation

2013 ◽  
Vol 716 ◽  
pp. 559-564
Author(s):  
Di Jia ◽  
Feng Hui Kang ◽  
Yi Na Wang
Keyword(s):  
Field Distribution ◽  
Sound Pressure ◽  
Pressure Field ◽  
Incident Angle ◽  
Near Field ◽  
Sound Field ◽  
Acoustic Characteristic ◽  
Considerable Influence ◽  
Compound Structure ◽  
Acoustic Environment

In order to study the acoustic environment of a ship sonar platform, near-field acoustic characteristic of a compound structure with plates & a cylindrical shell (CSPCS) subjected to sound excitation is researched based on numerical simulation. Influence of frequency and sound incident angle on acoustic environment of CSPCS are studied. Study shows that the sound pressure field distribution of CSPCS is complicated. Sound pressure would be strengthened and weakened in different locations when sound pressure uniformly incident into CSPCS. Result shows that the sound pressure distribution is highly dependent on frequency and incident angle. Sound pressure field is more evenly distributed when sound wave frequency is low. Study also shows that the incident angle has considerable influence on the sound field distribution of strengthened and weakened area.

Near Field Acoustic Holography for Cyclostationary Sound Field and its Partial Source Decomposition Procedure

2005 ◽  
Vol 127 (6) ◽  
pp. 542-546 ◽  
Author(s):  
Quan Wan ◽  
W. K. Jiang
Keyword(s):  
Principal Component Analysis ◽  
Sound Pressure ◽  
Near Field ◽  
Sound Field ◽  
Principal Component ◽  
Acoustic Holography ◽  
Sound Sources ◽  
Decomposition Procedure ◽  
Spectrum Density ◽  
Simulation Results

The cyclostationary near field acoustic holography (NAH) technique is proposed to overcome the limitations of the current NAH in analyzing cyclostationary sound field. The proposed technique adopts the cyclic spectrum density as the reconstructed physical quantity, instead of the spectrum of sound pressure. Moreover, introducing the principal component analysis into the technique, a partial source decomposition procedure is suggested to decompose the sound field radiated by multiple sound sources into some incoherent partial fields. More information about cyclostationary sound field can be shown clearly on the hologram of the proposed technique than NAH can, which is validated by the simulation results.

Simulation and experimental investigations for the patch near-field acoustical holography

2008 ◽  
Vol 222 (6) ◽  
pp. 945-953 ◽  
Author(s):  
C Yang ◽  
J Chen ◽  
J Q Li ◽  
W F Xue
Keyword(s):  
Fourier Transform ◽  
Sound Pressure ◽  
Near Field ◽  
Sound Field ◽  
Experimental Investigations ◽  
Regularization Methods ◽  
Aperture Size ◽  
Measurement Surface ◽  
Physical Necessity ◽  
Acoustical Holography

In order to reconstruct the sound field, the fast Fourier transform (FFT)-based near-field acoustical holography (NAH) demands that the measurement surface must extend to a region where the sound pressure decreases to a low level. This method is unfit for reconstructing the partial sound field in which the measurement aperture size is limited either by physical necessity or as a way of reducing the measurement cost. Statistically optimal NAH (SONAH) performs plane-to-plane calculations directly in the spatial domain, avoids all errors occurred in the FFT-based NAH and significantly increases the accuracy of the reconstruction of the partial sound field. In the present work, combined with the different regularization methods, SONAH is performed for reconstructing the partial sound field. The errors over the central and the peripheral sections of the reconstruction area are researched separately. Simulations and experiments show that SONAH is successful in reconstructing the partial sound field and the errors over the central sections are smaller than that over the peripheral sections. Experiments demonstrate that Tikhonov regularization in conjunction with Engl's criterion is suitable for the reconstruction of the practical sound field.

Modal Analysis of a Loudspeaker and Its Associated Acoustic Pressure Field

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Derek Kuo ◽  
Y. C. Shiah ◽  
Jin H. Huang
Keyword(s):  
Modal Analysis ◽  
Sound Pressure ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Near Field ◽  
Numerical Convergence ◽  
Supported Membrane ◽  
Near Field Sound ◽  
Elastically Supported ◽  
Field Sound

This paper presents a modal analysis and the sound pressure field for the vibrator membrane of an actual portable loudspeaker. Unlike the conventional way to model the membrane’s edge under a simply supported condition, the present approach takes the glued edge to be elastically supported. With theoretical derivations for such treatment, this paper also presents the associated near-field and far-field sound pressures that have not been reported in the open literature. Fundamentally, calculation of the near-field sound pressure solution for the elastically supported membrane has difficulty with numerical convergence. In this paper, integral regularization is employed to enforce the convergence. From the viewpoint of acoustic engineers, the analysis may effectively help to tailor the design of a loudspeaker that caters to consumers’ preference.

Near-Field Acoustic Holography of Cyclostationary Sound Field

2013 ◽  
Vol 631-632 ◽  
pp. 1318-1323
Author(s):  
Min Peng
Keyword(s):  
Time Series ◽  
Sound Pressure ◽  
Near Field ◽  
Sound Field ◽  
Rotating Machinery ◽  
Stationary Field ◽  
Acoustic Holography ◽  
Complex Sound ◽  
Radiated Sound ◽  
Slice Method

The radiated sound field of rotating machinery or reciprocating machinery has a significant periodically time-variant nature. This is a kind of non-stationary sound field and called cyclostationary sound field. In the conventional planar near-field acoustic holography(PNAH), this kind of sound field is treated as stationary field, so the information relating to the change of frequency with time will be loss inevitably. In this article, the cyclic spectral density(CSD) instead of the complex sound pressure was adopted as reconstructing physical quantity in the PNAH, and the cyclostationary PNAH(CPNAH) technique was proposed. Meanwhile, focusing on the calculation complex of CSD and the accuracy of the cyclic nature extracted, the gathering slice method of CSD was proposed by referring time aliasing methods on time series. The experiment results illustrate that the cyclic nature of cyclostationary sound field may be extracted directly and the location of the source determined exactly as well.

Research on the Planar Near-Field Acoustic Holography for Cyclostationary Sound Field

2011 ◽  
Vol 105-107 ◽  
pp. 164-167
Author(s):  
Zhi Min Chen ◽  
Hai Chao Zhu ◽  
Rong Fu Mao
Keyword(s):  
Spectral Density ◽  
Physical Quantity ◽  
Sound Source ◽  
Sound Pressure ◽  
Near Field ◽  
Sound Field ◽  
Rotating Machines ◽  
Carrier Wave ◽  
Acoustic Holography ◽  
Complex Sound

The conventional planar near-field acoustic holography is not suitable for cyclostationary sound field radiated by the rotating machines. When the cyclic spectral density (CSD), instead of the complex sound pressure, is adopted as reconstructed physical quantity, the modulating wave and carrier wave components of the cyclostationary sound field can be extracted exactly and so the cyclostationary planar near-field acoustic holography (CPNAH) technique was proposed. Simulation and experimental results show that the modulation characteristics of the cyclostationary sound field can be extracted effectively and the sound source can be localized accurately.

Sound Power Measurements in the Near Field of Transformers

2012 ◽  
Author(s):  
Michael Ertl ◽  
Hermann Landes
Keyword(s):  
Sound Pressure ◽  
Power Level ◽  
Near Field ◽  
Sound Field ◽  
Sound Intensity ◽  
Sound Level ◽  
Numerical Analyses ◽  
Sound Power ◽  
3D Fem ◽  
Sound Power Level

The international standard for the determination of the sound power level of transformers allows both the sound pressure and the sound intensity measurement method. Since the sound measurements take place in the reactive near-field next to the vibrating transformer tank walls, local disturbances influence the sound field characteristics at the measurement positions. As a result, the measured mean sound power level differs commonly up to 6dB at comparative measurements with both methods. Beyond these near field effects, the influence of an industrial measurement environment (background sound sources, hard-reflecting floor, semi-reverberant walls, and standing waves) to the sound pressure and sound intensity field characteristics is investigated. Hereby, numerical analyses based on 3D-FEM with consideration of the fluid-structure-coupling are used. The measured sound level differences can be re-produced and clarified in numerical analyses.

Active control of the scattered radiation with a reflecting surface

2019 ◽  
Vol 67 (3) ◽  
pp. 190-196
Author(s):  
Ning Han
Keyword(s):  
Control System ◽  
Active Control ◽  
Scattered Radiation ◽  
Sound Pressure ◽  
Sound Field ◽  
Control Area ◽  
Mirror Image ◽  
Three Dimension ◽  
Control Effect ◽  
Reflecting Surface

Based on a prediction method of the scattered sound pressure, an active control system was proposed in previous work for the three-dimension scattered radiation, where all the relevant simulations and experiments were implemented in three-dimensional free sound field. However, for practical applications, such as the anti-eavesdropping system or the stealth system for submarines, the sound field conditions are usually complex, and the most common case is the one with reflecting surface. It is questionable whether the previous control system is still effective in non-free sound field, or what improvements should be operated to ensure the control effect. In this article, based on the mirror image principle, two methods of calculating the control source strengths are proposed for the scattered radiation control, and numerical simulations with one-channel and multi-channel system are implemented to detect the corresponding control effect. It is seen that the local active control for the scattered radiation is still effective, and the reduction of the sound pressure level as well as the control area is extended with the increasement of the error sensors and control sources.

scholarly journals Research on the Manufacturing Quality of Co-Cured Hat-Stiffened Composite Structure

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2747
Author(s):  
Xiangwen Ju ◽  
Jun Xiao ◽  
Dongli Wang ◽  
Cong Zhao ◽  
Xianfeng Wang
Keyword(s):  
Composite Structures ◽  
Sound Pressure ◽  
Integration Method ◽  
Complex Geometry ◽  
Sound Field ◽  
Thickness Measurement ◽  
Curing Process ◽  
The Finite Element Method ◽  
Manufacturing Quality

The stringer-stiffened structure is widely used due to its excellent mechanical properties. Improving the manufacturing quality of stringer-stiffened structure which have complex geometry is important to ensure the bearing capacity of aviation components. Herein, composite hat-stiffened composite structures were manufactured by different filling forms and bladders with various properties, the deformation of silicone rubber bladder in co-curing process was studied by using the finite element method. The thickness measurement at different positions of the hat-stiffened structure was performed to determine the best filling form and bladder property. Moreover, in view of the detection difficulties in R-zone of stringer, numerical simulation was performed to get the sound pressure and impulse response of at the R-zone of stringer by Rayleigh integration method, and an effective equipment which could stably detect the manufacturing quality of R-zone was designed to verify the correctness of sound field simulation and realize the detection of stringer. With the optimum filling form and bladder properties, hat-stiffened composites can be manufactured integrally with improved surface quality and geometric accuracy, based on co-curing process.

scholarly journals Mathematical modeling and experimental study on solid–liquid suspension separation in ultrasonic standing wave field

2021 ◽  
pp. 146134842110229
Author(s):  
Yajing Wang ◽  
Liqun Wu ◽  
Yaxing Wang ◽  
Yafei Fan
Keyword(s):  
Standing Wave ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Sound Field ◽  
Radiation Force ◽  
High Energy ◽  
Factors Affecting ◽  
Liquid Suspension ◽  
Ultrasonic Standing Wave ◽  
Solid Liquid

A new method of removing waste chips is proposed by focusing on the key factors affecting the processing quality and efficiency of high energy beams. Firstly, a mathematical model has been established to provide the theoretical basis for the separation of solid–liquid suspension under ultrasonic standing wave. Secondly, the distribution of sound field with and without droplet has been simulated. Thirdly, the deformation and movement of droplets are simulated and tested. It is found that the sound pressure around the droplet is greater than the sound pressure in the droplet, which can promote the separation of droplets and provide theoretical support for the ultrasonic suspension separation of droplet; under the interaction of acoustic radiation force, surface tension, adhesion, and static pressure, the droplet is deformed so that the gas fluid around the droplet is concentrated in the center to achieve droplet separation, and the droplet just as a flat ball with a central sag is stably suspended in the acoustic wave node.

Sign in / Sign up

Export Citation Format

Share Document