Sound Radiation of Cylindrical Shells
The acoustic signature of submarines is very critical in such high performance structure. Submarines are not only required to sustain very high dynamic loadings at all time, but also being able maneuver and perform their functions under sea without being detected by sonar systems. Submarines rely on...
Main Authors: | , |
---|---|
Format: | Article |
Language: | English |
Published: |
Multi-Science Publishing
2016-09-01
|
Series: | International Journal of Multiphysics |
Online Access: | http://journal.multiphysics.org/index.php/IJM/article/view/174 |
id |
doaj-a4ddb61dd79742308783b1217aaced18 |
---|---|
record_format |
Article |
spelling |
doaj-a4ddb61dd79742308783b1217aaced182020-11-25T00:44:47ZengMulti-Science PublishingInternational Journal of Multiphysics1750-95482048-39612016-09-015210.1260/1750-9548.5.2.173186Sound Radiation of Cylindrical ShellsB Alzahabi0E Almic1Kettering University, Mechanical Engineering Department, 1700 University Ave., Flint, MI 48504-4898Kettering University, Mechanical Engineering Department, 1700 University Ave., Flint, MI 48504-4898The acoustic signature of submarines is very critical in such high performance structure. Submarines are not only required to sustain very high dynamic loadings at all time, but also being able maneuver and perform their functions under sea without being detected by sonar systems. Submarines rely on low acoustic signature level to remain undetected. Reduction of sound radiation is most efficiently achieved at the design stage. Acoustic signatures may be determined by considering operational scenarios, and modal characteristics. The acoustic signature of submarines is generally of two categories; broadband which has a continuous spectrum; and a tonal noise which has discrete frequencies. The nature of sound radiation of submarine is fiction of its speed. At low speed the acoustic signature is dominated by tonal noise, while at high speed, the acoustic signature is mainly dominated by broadband noise. Submarine hulls are mainly constructed of circular cylindrical shells. Unlike that of simpler structures such as beams and plates, the modal spectrum of cylindrical shell exhibits very unique characteristics. Mode crossing, the uniqueness of modal spectrum, and the redundancy of modal constraints are just to name a few. In cylindrical shells, the lowest natural frequency is not necessarily associated with the lowest wave index. In fact, the natural frequencies do not fall in ascending order of the wave index either. Solution of the vibration problem of cylindrical shells also indicates repeated natural frequencies. These modes are referred to as double peak frequencies. Mode shapes associated with each one of the natural frequencies are usually a combination of Radial (flexural), Longitudinal (axial), and Circumferential (torsional) modes. In this paper, the wave equation will be set up in terms of the pressure fluctuations, p(x, t). It will be demonstrated that the noise radiation is a fluctuating pressure wave.http://journal.multiphysics.org/index.php/IJM/article/view/174 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
B Alzahabi E Almic |
spellingShingle |
B Alzahabi E Almic Sound Radiation of Cylindrical Shells International Journal of Multiphysics |
author_facet |
B Alzahabi E Almic |
author_sort |
B Alzahabi |
title |
Sound Radiation of Cylindrical Shells |
title_short |
Sound Radiation of Cylindrical Shells |
title_full |
Sound Radiation of Cylindrical Shells |
title_fullStr |
Sound Radiation of Cylindrical Shells |
title_full_unstemmed |
Sound Radiation of Cylindrical Shells |
title_sort |
sound radiation of cylindrical shells |
publisher |
Multi-Science Publishing |
series |
International Journal of Multiphysics |
issn |
1750-9548 2048-3961 |
publishDate |
2016-09-01 |
description |
The acoustic signature of submarines is very critical in such high performance structure. Submarines are not only required to sustain very high dynamic loadings at all time, but also being able maneuver and perform their functions under sea without being detected by sonar systems. Submarines rely on low acoustic signature level to remain undetected.
Reduction of sound radiation is most efficiently achieved at the design stage. Acoustic signatures may be determined by considering operational scenarios, and modal characteristics. The acoustic signature of submarines is generally of two categories; broadband which has a continuous spectrum; and a tonal noise which has discrete frequencies.
The nature of sound radiation of submarine is fiction of its speed. At low speed the acoustic signature is dominated by tonal noise, while at high speed, the acoustic signature is mainly dominated by broadband noise. Submarine hulls are mainly constructed of circular cylindrical shells.
Unlike that of simpler structures such as beams and plates, the modal spectrum of cylindrical shell exhibits very unique characteristics. Mode crossing, the uniqueness of modal spectrum, and the redundancy of modal constraints are just to name a few.
In cylindrical shells, the lowest natural frequency is not necessarily associated with the lowest wave index. In fact, the natural frequencies do not fall in ascending order of the wave index either. Solution of the vibration problem of cylindrical shells also indicates repeated natural frequencies. These modes are referred to as double peak frequencies. Mode shapes associated with each one of the natural frequencies are usually a combination of Radial (flexural), Longitudinal (axial), and Circumferential (torsional) modes.
In this paper, the wave equation will be set up in terms of the pressure fluctuations, p(x, t). It will be demonstrated that the noise radiation is a fluctuating pressure wave. |
url |
http://journal.multiphysics.org/index.php/IJM/article/view/174 |
work_keys_str_mv |
AT balzahabi soundradiationofcylindricalshells AT ealmic soundradiationofcylindricalshells |
_version_ |
1725273422400847872 |