Identification of whispering gallery type waves on a finite cylindrical shell using MIIR

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.

Download Full-text

Probabilistic model for time-dependent transfer problems in finite cylindrical shell medium

Astrophysics and Space Science ◽

10.1007/bf00645720 ◽

1972 ◽

Vol 19 (2) ◽

pp. 369-385 ◽

Cited By ~ 2

Author(s):

T. K. Leong

Keyword(s):

Cylindrical Shell ◽

Probabilistic Model ◽

Time Dependent ◽

Finite Cylindrical Shell ◽

Transfer Problems

Download Full-text

Point load response of a finite cylindrical shell with a convected internal fluid

The Journal of the Acoustical Society of America ◽

10.1121/1.2028354 ◽

1990 ◽

Vol 87 (S1) ◽

pp. S74-S74

Author(s):

G. Leyrat ◽

J. M. Cuschieri

Keyword(s):

Cylindrical Shell ◽

Point Load ◽

Load Response ◽

Internal Fluid ◽

Finite Cylindrical Shell

Download Full-text

Simulation and analysis on low-frequency scattering characteristics of the finite cylindrical shell in shallow water

MATEC Web of Conferences ◽

10.1051/matecconf/201928303007 ◽

2019 ◽

Vol 283 ◽

pp. 03007

Author(s):

Jinyu Li ◽

Dejiang Shang ◽

Yan Xiao

Keyword(s):

Cylindrical Shell ◽

Free Space ◽

Acoustic Scattering ◽

Low Frequency ◽

Target Strength ◽

Wave Direction ◽

Scattering Field ◽

Simulation Results ◽

Finite Cylindrical Shell ◽

Target Locations

Low-frequency acoustic scatterings from a finite cylindrical shell are numerically analyzed by FEM. The simulation results show that the acoustic-scattering field in waveguide has lots of frequency-related sidelobes, while no sidelobes exist in free space at low frequencies. The simulation also indicates that the module value in waveguide can be almost 20 dB larger than that in free space at low frequency, which is caused by the ocean boundaries. We also demonstrate that when the incident wave direction is normal to the target at low frequency, the target strength will be maximum and the distribution of the acoustic-scattering field is axisymmetric about the incident waving direction. Meanwhile, the acoustic-scattering field is also related to the impedance of the seabed, and the change of the impedance makes just a little contribution to the scattering field. Finally, the influence of different target locations is analyzed, including the targets near the sea surface, seabed and the middle region of the ocean waveguide, respectively. From simulation results, it is evident that the distribution of the acoustic-scattering field at low frequency has a little difference, which is smaller than 0.5 dB with various target locations, and the change is frequency and boundary-related.

Download Full-text