| Project/Area Number |
16360377
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Metal making engineering
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| Research Institution | Tokyo Metropolitan University (2005-2006)
Tokyo Metropolitan Institute of Technology (2004) |
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Principal Investigator |
HIBIYA Taketoshi Tokyo Metropolitan University, Department of Aero-space Engineering, システムデザイン学部, 教授 (60347276)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥13,400,000 (Direct Cost: ¥13,400,000)
Fiscal Year 2006: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2004: ¥6,000,000 (Direct Cost: ¥6,000,000)
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| Keywords | molten silicon / Marangoni convection / instability / centrifugal instability / elliptic instability / low Ma-number / molten silver / wavelet transformation / 低マランゴニ数 / 半導体シリコン融液 / 酸素分圧 / 低プラントル流体 / 溶融銀 / 過冷却 / 酸素過飽和 / モード / 対称性 / 周波数 / wavelet変換 / 部分自由表面液柱 |
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| Research Abstract |
Temperature oscillation and surface oscillation were examined experimentally using thermocouples and phase-shift interferometry for Marangoni convection in the geometry of a half-zone structure. For instability at high Reynolds (Marangoni) number region, various mode wave numbers appeared time-dependently. The relationship between the aspect ratio of a liquid bridge and mode wave number was kept even for high Reynolds (Marangoni) number conditions, as long as frequency of appearance of mode wave numbers was observed. Trough the wavelet transformation analysis, band structures of oscillations with various frequencies were observed for the condition with the Marangoni number of 10^4. It was also confirmed that the mode wave numbers, which appeared when flow mode transition took place from stationary to oscillator one, were sustained.
Under the low Reynolds (Marangoni) number conditions, numerical modeling was performed for the liquid bridge with partial confinement and flow structure and mechanism of instability were discussed as functions of the bridge height, the open area ratio and the position of a open window. We found for the first time that two mechanisms, i.e., elliptical and centrifugal instabilities contribute to flow mode transition from stationary one to oscillatory one. The shorter the liquid bridge is, the more spherical the main flow cell becomes. It is also the case, when the open window is located at the hot are. These suggest that under these conditions elliptical instability becomes weak and that centrifugal instability becomes comparably dominant. Direct transition was also found when the open window is located at the hot portion of the liquid bridge. Flow structure was similar to that of the normal half zone structure, when the open window is located at the cold side. This geometry is effective to reduce the Marangoni number experimentally.
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