Numerical simulation of free shear flows and far-field sound pressure directivity

1994 ◽  
Vol 18 (4) ◽  
pp. 337-359 ◽  
Author(s):  
W. Y. Soh
Keyword(s):  
Numerical Simulation ◽  
Sound Pressure ◽  
Shear Flows ◽  
Far Field ◽  
Field Sound

Reconstruction of the unsteady rotating forces of fan’s blade from far-field sound pressure

2014 ◽  
Vol 86 ◽  
pp. 126-137 ◽  
Author(s):  
Hassen Trabelsi ◽  
Majdi Abid ◽  
Mohamed Taktak ◽  
Tahar Fakhfakh ◽  
Mohamed Haddar
Keyword(s):  
Sound Pressure ◽  
Far Field ◽  
Field Sound

Prediction of Far-Field Sound Pressure of a Semisubmerged Cylindrical Shell With Low-Frequency Excitation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
T. Y. Li ◽  
P. Wang ◽  
X. Zhu ◽  
J. Yang ◽  
W. B. Ye
Keyword(s):  
Cylindrical Shell ◽  
Free Surface ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Phase Method ◽  
Far Field ◽  
Radiation Model ◽  
New Approaches ◽  
Modal Coupling ◽  
Field Sound

A sound–structure interaction model is established to study the vibroacoustic characteristics of a semisubmerged cylindrical shell using the wave propagation approach (WPA). The fluid free surface effect is taken into account by satisfying the sound pressure release condition. Then, the far-field sound pressure is predicted with shell's vibration response using the stationary phase method. Modal coupling effect arises due to the presence of the fluid free surface. New approaches are proposed to handle this problem, i.e., diagonal coupling acoustic radiation model (DCARM) and column coupling acoustic radiation model (CCARM). New approaches are proved to be able to deal with the modal coupling problem efficiently with a good accuracy at a significantly reduced computational cost. Numerical results also indicate that the sound radiation characteristics of a semisubmerged cylindrical shell are quite different from those from the shell fully submerged in fluid. But the far-field sound pressure of a semisubmerged shell fluctuates around that from the shell ideally submerged in fluid. These new approaches can also be used to study the vibroacoustic problems of cylindrical shells partially coupled with fluid.

A Technique to Predict the Acoustic Radiation Characteristics of an Automobile Tire

1986 ◽  
Vol 14 (2) ◽  
pp. 102-115 ◽  
Author(s):  
C. Wright ◽  
G. H. Koopmann
Keyword(s):  
Close Agreement ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Surface Velocity ◽  
Experimental Measurements ◽  
Far Field ◽  
Radiation Characteristics ◽  
Automobile Tire ◽  
Electrodynamic Vibrator ◽  
Field Sound

Abstract A technique to predict the acoustic radiation characteristics of the predominant structural modes of an automobile tire is presented. A stationary tire is excited by an electrodynamic vibrator and, through conventional modal analysis methods, a description of the surface velocity is obtained. With this information, and a representation of the tire geometry, numerical procedures are used to predict the acoustic surface intensity and field pressure, for a given frequency of interest, based on a Helmholtz integral formulation. Predicted far field sound pressure levels are in close agreement with experimental measurements taken in an anechoic chamber. This provided the necessary validation of the technique.

The Vibro-Acoustic Characteristics of the Cylindrical Shell Partially Submerged in the Fluid

2012 ◽  
Vol 170-173 ◽  
pp. 2303-2311 ◽  
Author(s):  
Wen Bing Ye ◽  
Tian Yun Li ◽  
Xiang Zhu
Keyword(s):  
Cylindrical Shell ◽  
Free Surface ◽  
Power Flow ◽  
Sound Pressure ◽  
Harmonic Excitation ◽  
Input Power ◽  
Far Field ◽  
Fluid Coupling ◽  
Vibrational Power Flow ◽  
Field Sound

The characteristics of the sound radiation and vibrational power flow of the partially submerged cylindrical shell under a harmonic excitation are studied. The approximate acoustic boundary of the free surface is used to solve the fluid domain. The structure-fluid coupling equation is established based on the Flügge and Helmholtz theories. The far-field sound pressure is calculated and compared with that in infinite field. It is found that the far-field sound pressure presents large gap in different immersion status in the presence of the free surface while the results of the input power flow in these cases have less differences.

scholarly journals An Analytical Solution for the Vibration and Far-Field Sound Radiation Analysis of Finite, Semisubmerged Cylindrical Shells

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Wenjie Guo ◽  
Zhou Yang ◽  
Yueyang Han
Keyword(s):  
Cylindrical Shell ◽  
Free Surface ◽  
Present Method ◽  
Sound Pressure ◽  
Low Frequency ◽  
Sound Radiation ◽  
Far Field ◽  
Vibration Responses ◽  
Frequency Excitation ◽  
Field Sound

The vibration response and far-field sound radiation of a semisubmerged, finite cylindrical shell with low-frequency excitation are studied. The solution to this problem can be divided into two steps. The first step is to apply the wave propagation approach to determine the vibration response of the cylindrical shell. In the cylindrical coordinate system, the Flügge shell equations and Laplace equation are used to describe the cylindrical shell and surrounding fluid so that the vibration responses of the shell can be addressed analytically. The fluid free surface effect is taken into account by applying the sine series to force the velocity potential on the free surface to be zero. Furthermore, compared with the FEM (the finite element method), the present method is not only reliable but also effective. In the second step, the far-field sound radiation is solved by the Fourier transform technique and the stationary phase method in accordance with the vibration responses of the shell from the previous step. The boundary element method is applied to validate the reliability of the acoustical radiation calculation. The circumferential directivity of far-field sound pressure is discussed, and it is found that the maximum value of the sound pressure always appears directly under the structure when the driving frequencies are relatively low. Besides, in consideration of simplicity and less computation effort, the present method can be used for the rapid prediction of the vibration and far-field sound pressure of a semisubmerged cylindrical shell with low-frequency excitation.

Analysis of the near-field and far-field sound pressure generated by high-speed trains pantograph system

2020 ◽  
Vol 169 ◽  
pp. 107506
Author(s):  
Yue-ying Zhao ◽  
Zhi-gang Yang ◽  
Qi-liang Li ◽  
Chao Xia
Keyword(s):  
High Speed ◽  
Sound Pressure ◽  
Near Field ◽  
Far Field ◽  
High Speed Trains ◽  
Field Sound

Control of tonal noise from subsonic axial fan. Part 1: reconstruction of aeroacoustic sources from far-field sound pressure

2005 ◽  
Vol 288 (4-5) ◽  
pp. 1049-1075 ◽  
Author(s):  
Anthony Gérard ◽  
Alain Berry ◽  
Patrice Masson
Keyword(s):  
Sound Pressure ◽  
Far Field ◽  
Axial Fan ◽  
Tonal Noise ◽  
Field Sound

Sound Radiation From Shear Deformable Stiffened Laminated Plates With Multiple Compliant Layers

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Xiongtao Cao ◽  
Hongxing Hua
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Plate Theory ◽  
Sound Radiation ◽  
Laminated Plates ◽  
Far Field ◽  
Frequency Range ◽  
First Order ◽  
Shear Deformable ◽  
Field Sound

Sound radiation from shear deformable stiffened laminated plates with multiple compliant layers is theoretically studied. Equations of motion for the composite laminated plates are on the basis of the first-order shear deformation plate theory, and the transfer matrix method is used to describe sound transmission through compliant layers. The first and second sets of stiffeners interact with the plate through normal line forces. By using the Fourier transform and stationary phase method, the far-field sound pressure is obtained in terms of analytical expressions. Comparisons are made between the first-order shear deformation plate theory and the classical thin plate theory. Three principal conclusions are drawn in the study. (1) The transverse point force acting on the stiffeners yields lower far-field sound pressure in the middle and high frequency range. Specifically, the transverse point force exerting on the large stiffeners produces the lowest far-field sound pressure among three different reactive points at the plate, small stiffener and large stiffener. (2) The far-field sound pressure spectra are confined by an acoustic circle and remain unchanged. Lots of flexural waves in the structure cannot radiate sound into the far field. (3) The sound attenuation of stiffened plates with compliant layers is mainly caused by the sound isolation of compliant layers rather than vibrational reduction. Compliant layers can effectively reduce the radiated sound pressure in the medium and high frequency range.

Acoustic Cloaking with Realizable Mass

2014 ◽  
Vol 670-671 ◽  
pp. 1093-1097
Author(s):  
Ai Guo Zhao ◽  
Hong Chen ◽  
Zhi Gao Zhao ◽  
Jia Chang Qian ◽  
Lei Wang
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Target Strength ◽  
Far Field ◽  
Material Parameters ◽  
Full Wave ◽  
Scattering Field ◽  
Reasonable Range ◽  
Field Sound

A nonideal acoustic cloak with realizable physical properties is proposed. The density and modulus of the designed acoustic cloak are in a reasonable range of material parameters. Full-wave simulations are performed to demonstrate the properties of the proposed cloak. Results on far-field sound pressure level show that the nonideal acoustic cloak decreases the scattering field intensity and the target strength (TS) of the scatterer. The nonideal acoustic cloak also has significant effect on suppressing internal radioactive noise. A comparison is made with the reduced cloak proposed by Chen.

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