Mechanism and its application of bubble sounds induced by the drop impact in the irregular entrainment region
| Project/Area Number |
17560132
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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 Hokkaido University of Education, Faculty of Education, Professor, 教育学部, 教授 (00006199)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Kotaro Kogakuin University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (80252625)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2005: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | Water Droplet / Bubble / Impact Phenomena / Liquid Jet / Water Column / Underwater Sound / Surface Breakup / Suikinkutsu / 流体 / 可視化 / シミュレーション工学 / 人間生活環境 |
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| Research Abstract |
An experiment was carried out for investigating the mechanism of surface breakup due to drop impact on a free surface and induced underwater sounds for the range of Froude number Fr 300. Application of these sounds to an open-type Suikinkutsu was also examined.
(1) A falling drop changes its shape oscillatory depending on the Weber number, then impacts onto a water surface. When a drop impacts with the shape being prolate the resultant splash is relatively weak compared to the oblate drop impact case.
(2) Three times of underwater sounds were generated for a single shot of drop impact. The first sound resulted from the oscillation of a single air bubble formed as a result of the satellite drop impact on the bottom of a cavity under contracting, and the second sound was due to the oscillation of air bubbles generated during the collapse of a water column. The formation of these air bubbles strongly depends on the Fr number, We number (or Bond number) and the aspect ratio of a drop at impa
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ct, although involving probability characteristics. An air bubble entrapped into a water column plays an important role in elevating the probability of contact between the column surface and curved free surface.
(3) Once drop impact is generated inside a water jar, the sounds propagate through the water surface into the air inside the jar and reflect many times on the wall surface of the jar, producing a reverberant sound with a long duration which is a peaceful and healing sound. An experiment was also performed by using drops with the average diameters of 6.2, 7.2 and 7.8mm in order to investigate the effects of water flow rate and water temperature on the Suikinkutsu sound. For generating a powerful sound of Suikinkutsu, therefore, water temperature should be maintained as low as possible.
The results mentioned above have been presented and published at various meetings. More recently our paper associated with the surface breakup and bubble sounds has been accepted for publication in the Journal of Fluid Mechanics. Less
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Report
(3 results)
Research Products
(21 results)
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[Journal Article] 12.3 Bubble dynamics2006
Author(s)
Y.Tomita
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Journal Title
In JSME Mechanical Engineer's Handbook, Fundamentals, α4 : Fluids Engineering(ed.JSME)(Maruzen)(in Japanese)
Description
「研究成果報告書概要(欧文)」より
Related Report
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