碩士 / 國立臺灣海洋大學 / 系統工程暨造船學系 / 107 / The purpose of this thesis focuses on two parts. One is the effect of the internal structure design of the underwater vehicle on the noise radiation generated by the machine vibration, and the other is the effect of the underwater vehicle on the scattering effect of plane wave incidence in different directions. Radiation and scattering are very important for the field of underwater acoustics. Using methods to reduce the radiation and scattering of noise so as not to be detected is a significant issue.
The structure-borne noise of underwater vehicles is an important issue. Due to the rapid development of the computing, we can predict the radiation of underwater vehicles through simulation at the design phase. The amount of noise is related to the following factors: vibration specifications, the best operating frequency of the machines, main structure of the vehicles and the supporting structures of the machines. It’s difficult to adjust the machines and the main structure.
The first part focuses on the supporting structures. To investigate the use of different arrangements of T-shaped reinforcing ribs to reduce the machine vibration, we built a simplified model which is made up of cylinder, two hemispheres and the loading platform inside. The element of the model is shell. First, we compared the resonance frequency of the whole structure and only the loading platform in the condition of the air. Second, we used the same models to calculate the underwater acoustic radiation. Lastly we summarized the most suitable designs and arrangements of each frequency bands according to the increased weight of the T-shaped ribs.
The second part of the research used BeTSSi model in the scattering simulation. Setting plane wave incidence in different directions simulates the surface pressure of the shell of the underwater vehicle, and the sound field pressure transmitted to the far field. In this way, the impact of geometry on the measurement of the pressure and the production of the sound field pressure in different incidence angles of the plane wave were observed.
| Identifer | oai:union.ndltd.org:TW/107NTOU5345016 |
| Date | January 2019 |
| Creators | Yu-Jen Chen, 陳宥任 |
| Contributors | Pei-Tai Chen, 陳柏台 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 62 |
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