Experimental works for intermediate and low Pr: Transition to oscillatory Marangoni convection in liquid bridges of intermediate prandtl number
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宇宙開発事業団
エイ・イー・エス
University of Toronto Dept. of Chemical Eng. and Applied Chem.
宇宙開発事業団
著者所属（英）
National Space Development Agency of Japan
Advanced Engineering Services Co. Ltd.
University of Toronto Department of Chemical Engineering and Applied Chemistry
National Space Development Agency of Japan
出版者
宇宙開発事業団
出版者（英）
National Space Development Agency of Japan (NASDA)
雑誌名
宇宙開発事業団技術報告: Marangoni Convection Modeling Research: Annual Report April 1, 1999 - March 31, 2000
雑誌名(英)
NASDA Technical Memorandum: Marangoni Convection Modeling Research: Annual Report April 1, 1999 - March 31, 2000
ページ
73 - 114
発行年
2000-09-29
抄録（英）
Marangoni convection experiments have been conducted with acetone (Pr = 4.3) and methanol (Pr = 6.8) liquid bridges to investigate the flow structures and temperature fields during transition from steady to oscillatory convection in a half floating zone. The disk diameters of 5.0 mm and 10.0 mm were used for both fluids and the liquid bridge height was changed from 1.5 mm to 4.5 mm, covering aspect ratios from 0.3 up to 1.6. Various advanced measurement techniques were employed to yield detailed experimental data useful for both understanding the mechanism responsible for transition as well as verifying linear stability analysis and three-dimensional numerical simulation predictions. In order to reduce the surface evaporation rate, a quartz tube was fitted around the liquid bridge for both fluids. The liquid bridge shape data were obtained for both fluids covering a wide range of volume ratios for each aspect ratio and disk diameter. For acetone, the transition from steady to oscillatory convection was found to occur at disk temperature differences of 1.3 to 2.3 K, and liquid temperature fluctuations with amplitudes of 0.02 to 0.1 K were detected. For methanol, oscillatory flow appeared at disk temperature differences ranging from 1.6 to 4.3 K. For acetone, the transition was also accompanied by the appearance of an azimuthal component of surface velocity. At the same time, the toroidal vortex started to expand and contract in size, and the radial flow field started to rotate. Although the surface displacement was measured, surface oscillations could not be detected probably because of an insufficient driving force arising from small temperature differences. The critical Marangoni numbers for acetone were found to be higher than the values extrapolated from existing data, due to the effects of evaporation and added heat loss from the liquid surface. On the other hand, the critical Marangoni numbers for methanol showed good agreement with the existing data for a similar Prandtl number.
Experimental works for intermediate and low Pr: Transition to oscillatory Marangoni convection in liquid bridges of intermediate prandtl number
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