2000 Fiscal Year Final Research Report Summary
Study on the cleaning effect by ultrasonic cavitation accompanying with a water jet
| Project/Area Number |
11650161
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Hokkaido University of Education |
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Principal Investigator |
TOMITA Yukio Faculty of Education, Hokkaido University of Education ; Professor, 教育学部・函館校, 教授 (00006199)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Kotaro Faculty of Engineering, Kogakuin University ; Associate Professor, 工学部, 助教授 (80252625)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Cavitation / Bubble / Ultrasonic waves / Water Jet / Underwater Acoustics / Cleaning / Shock Waves / Bubble Microjet |
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| Research Abstract |
During the first term of the research project, we primarily investigated the characteristic of ultrasonically produced cavitation. Cavitation was ultrasonically generated in tap water by using an ultrasonic vibrator with the resonance frequency of 28kHz. The behavior of cavitation was observed with a high-speed video camera. Impulsive pressures caused by cavitation were measured with a pressure transducer and cavitation noise measurement was also conducted by using a hydrophone. The signals were fed into a FFT analyzer to examine their power spectra.
During the second term, we carried out an experiment for understanding the cleaning effect due to fluid motion by employing a nickel plate covered with a PbCl_2 film several μm thick as a test wall. The individual nickel plates were set on the surface of an upper static wall and exposed to three different situations of fluid motion such as (1) flow induced only by a water jet, (2) flow induced only by an ultrasonic cavitation and (3) flow induced by (1) combined with (2). The damaged surface of the nickel plate was observed by employing a microscope equipped with a CCD camera. It was found that the film separation took place in all situations, (1)-(3), depending on the forces acting on the wall surface.
Furthermore cavitation bubble dynamics has been investigated by means of several methods of theoretical approach. Some of the results obtained have been published in several journals.
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