1993 Fiscal Year Final Research Report Summary
Destructive Action of Shock Focusing-Induced Cavitation and Research on Its Suppression
| Project/Area Number |
04650140
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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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 ; Associate Professor, 教育学部・函館校, 助教授 (00006199)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAYAMA Kazuyoshi Institute of Fluid Science, Tohoku University ; Professor, 流体科学研究所, 教授 (40006193)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Cavitation / Shock Wave / Bubble / Shock Wave / Bubble Interaction / Bubble / Bubble Interaction / ESWL / Tissue Damage / Pressure Transducer |
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| Research Abstract |
A detailed observation of shock focusing and induced cavitation phenomena was continiously carried out using a reflector which is one of the same type as that commercialized in Japan. We especially noticed the effect of the exit configuration of the reflector on the cavitation occurence at the 2nd focal point of the ellipsoidal reflector. As a result, it is suggested that cavitation is relatively suppressed in the case where the exit surface of the reflector changes not abruptly but gradually curved shape, resulting in weak focusing of expansion waves at the 2nd focal point. On the other hands, for the purpose of understanding complicated phenomena appearing at around 2nd focal point of the reflector several elementary researches have been conducted, such as shock wave/bubble interaction and bubble/bubble interaction. An experiment was also performed, in which a bubble attached on a gelatine wall was hit by a shock wave. Consequently a higher liquid microjet was formed, piercing into the gelatine layr. Furthermore the bubble/bubble interaction was examined using two bubbles generated by means of a laser. It was found that an individual bubble can take several modes of the bubble motion, depending on the bubble size, distance between two bubbles and time difference of bubble generations. When two bubbles are affecting each other, an interesting phenomena such as the jet formation with higher velocity, the bubble disintegration and the vortex ring formation, occurred. The most of results obtained are already reported at both national and international symposia, and also published in journals.
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