| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 100 === Two-phase fuids play an important role in acoustic systems. One of the outstanding effects of this mentioned phenomenon is scattering and attenuating the sound, which passes through the phases. Although there have been many studies about sound scattering and attenuating through air-bubbles, there are not many experiments performed on the CO2 bubbles effect on sound propagation. Despite the fact that CO2 has high solubility in water which could be a good candidate for these tests, no study has been carried out in this way. It was assumed that CO2 bubbles are smaller than air bubbles which is because of their solubility. Therefore, sound attenuation through CO2 bubbles should be higher in comparison to air bubbles. To examine this assumption, we carried out some experiments which,limited the working frequency range to be within 10 to 100 kHz. Bubble size and void fraction measurements were conducted with a CCD camera, using acoustic method (inverse frequency) and (Su andWesson)1 method respectively. By doing these experiments, we realized that as CO2 is absorbed by water, the void fractions and bubble screen widths become smaller than air bubbles using the same ow rate. It must be noted that the experimental data has a good correlation with the classical theory of sound propagation through bubble fluid. The experimental results, either by photography or acoustic method, prove our assumption that the CO2 bubbles diameter is smaller than that of air-bubbles. However, the sounds attenuation for CO2 was less than that of air-bubbles due to the smaller void fractions and bubble screen widths.
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