Far-field acoustic radiation and vibration of a submerged finite cylindrical shell below the free surface based on energy functional variation principle and stationary phase method

2017 ◽  
Vol 65 (6) ◽  
pp. 565-576
Author(s):  
Wenjie Guo ◽  
Tianyun Li ◽  
Xiang Zhu
Keyword(s):  
Cylindrical Shell ◽  
Free Surface ◽  
Acoustic Radiation ◽  
Energy Functional ◽  
Phase Method ◽  
Stationary Phase Method ◽  
Variation Principle ◽  
Far Field ◽  
Functional Variation ◽  
Finite Cylindrical Shell

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.

Acoustic Radiation From Stiffened Cylindrical Shells With Constrained Layer Damping

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Xiongtao Cao ◽  
Hongxing Hua ◽  
Zhenguo Zhang
Keyword(s):  
Cylindrical Shell ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Equations Of Motion ◽  
Cylindrical Shells ◽  
Phase Method ◽  
Stationary Phase Method ◽  
Constrained Layer Damping ◽  
Acoustic Characteristics ◽  
Stiffened Cylindrical Shell

Acoustic radiation from cylindrical shells stiffened by two sets of rings, with constrained layer damping (CLD), is investigated theoretically. The governing equations of motion for the cylindrical shell with CLD are described on the basis of Sanders thin shell theory. Two sets of rings interact with the host cylindrical shell only through the normal line forces. The solutions are derived in the wavenumber domain and the stationary phase method is used to find an analytical expression of the far-field sound pressure. The effects of the viscoelastic material core, constrained layer and multiple loadings on sound pressure are illustrated. The helical wave spectra of sound pressure and the radial displacement clearly show the vibrational and acoustic characteristics of the stiffened cylindrical shell with CLD. It is shown that CLD can effectively suppress the radial vibration and reduce acoustic radiation.

Vibration and acoustic radiation of a finite cylindrical shell submerged at finite depth from the free surface

2017 ◽  
Vol 393 ◽  
pp. 338-352 ◽  
Author(s):  
Wenjie Guo ◽  
Tianyun Li ◽  
Xiang Zhu ◽  
Yuyue Miao ◽  
Guanjun Zhang
Keyword(s):  
Cylindrical Shell ◽  
Free Surface ◽  
Acoustic Radiation ◽  
Finite Depth ◽  
Finite Cylindrical Shell

Vibrational and acoustic radiation from a submerged periodic cylindrical shell with axial stiffening

2009 ◽  
Vol 223 (5) ◽  
pp. 1083-1089 ◽  
Author(s):  
C-J Liao ◽  
W-K Jiang ◽  
H Duan ◽  
Y Wang
Keyword(s):  
Cylindrical Shell ◽  
Analytical Study ◽  
Acoustic Radiation ◽  
Sound Radiation ◽  
Mechanical Impedance ◽  
Stiffened Cylindrical Shell ◽  
Reaction Forces ◽  
Radial Forces ◽  
Vibration And Sound Radiation ◽  
Finite Cylindrical Shell

An analytical study on the vibration and acoustic radiation from an axially stiffened cylindrical shell in water is presented. Supposing that the axial stiffeners interact with the cylindrical shell only through radial forces, the reaction forces on the shell from stiffeners can be expressed by additional impedance. The coupled vibration equation of the finite cylindrical shell with axial stiffening is derived; in this equation additional impedance caused by the axial stiffeners is added. As a result, the vibration and sound radiation of the shell are dependent on the mechanical impedance of the shell, the radiation sound impedance, and the additional impedance of the axial stiffeners. Based on the numerical simulation, it is found that the existence of axial stiffeners decreases the sound radiation and surface average velocity, whereas it increases the radiation factor. The characteristics of the acoustic radiation can be understood from the simulation with good results, which show that the presented methodology can be used to study the mechanism of the acoustic radiation of the complicated cylindrical shell and to optimize its design.

scholarly journals Surface water waves due to an oscillatory wavemaker in the presence of surface tension

1992 ◽  
Vol 15 (2) ◽  
pp. 399-404
Author(s):  
B. N. Mandal ◽  
S. Banerjea
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Surface Water ◽  
Water Waves ◽  
Phase Method ◽  
Stationary Phase Method ◽  
Transient Component ◽  
Surface Water Waves ◽  
Qualitative Nature ◽  
Surface Depression

The initial value problem of generation of surface water waves by a harmonically oscillating plane vertical wavemaker in an infinite incompressible fluid under the action of gravity and surface tension is investigated. In the asymptotic evaluation of the free surface depression for large time and distance, the contribution to the integral by stationary phase method gives rise to transient component of the free surface depression while the contribution from the poles give rise to steady state component. It is observed that the presence of surface tension sometimes changes the qualitative nature of the transient component of free surface depression.

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.

Acoustic and Vibration Characteristics of Finite Cylindrical Shell-Circular Plate Based on Lagrange Equations

2013 ◽  
Vol 302 ◽  
pp. 401-405
Author(s):  
Qi Zheng Zhou ◽  
De Shi Wang ◽  
Shu Yang
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Circular Plate ◽  
Acoustic Radiation ◽  
Vibration Characteristics ◽  
Finite Cylinder ◽  
Lagrange Equations ◽  
Coupling Conditions ◽  
Set Up ◽  
Finite Cylindrical Shell

An analysis based on Lagrange equations was presented for acoustic and vibration characteristics of finite cylindrical shell-circular plate underwater. The boundary conditions and coupling conditions between the shell and plate expressed using springs, the model of finite shell with circular plate was set up. Considering the elastic potential energy in springs and the work due to fluid loading, the vibro-acoustic equations of finite cylinder with circular plate under excitation were established by Lagrange equations. The influences of boundary conditions and coupling conditions to the acoustic and vibration characteristics were researched. The results show that . The results could be used to control the underwater vehicle’s vibration and acoustic radiation.

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.

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