Bubbles are often present in the natural ocean. Bubbly liquid will have the significant influence the sound propagation, and creates a significant disturbance to under water target's detection. Therefore, it is an important research subject of bubble influence to the sound wave propagation. This study used the sonar training system which developed by British's iTP corporation, through suitable additional design discuss the attenuation of sound propagating through a bubble screen. At first this study collects and infers the formula by the literature review. Secondly, the experimental design of measuring the attenuation of sound wave. The experiment process by using two parallel iron boards to carry on the measurement of gas-volume fraction. Then correlate with the sound pressure from the measurement of hydrophone. After curve fitting, we can clearly know the each other correlation. Finally taking the result compare with the attenuation coefficient formula. The experimental consists of two parts. The first part is to measure the gas-volume fraction of the bubbly liquid contained in the screen; while the second part is to measure the sound attenuation of the bubble screen. The result display that the bubble screen can attenuate about 8 dB per centimeter as the gas-volume fraction stay at 1 percent. At high gas-volume fraction the coefficient of attenuation has increased, and is different from theoretical value. This is because the bubble's correlation has not been considered. In addition, the low frequency sound wave is close to theoretical value, but the high frequency sound wave has big different to theoretical value. Because the high frequency sound wave's wavelength is too small to satisfy the condition. At experiment I suggest to use more appropriate transducers and precise bubble's tube. Thus the experimental result will be better.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0903107-161038 |
| Date | 03 September 2007 |
| Creators | Wu, Cheng-kang |
| Contributors | Ching-jhe Huang, Jin-yuan Liu, Hsiao-hsin Lu |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0903107-161038 |
| Rights | unrestricted, Copyright information available at source archive |
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