並列タイトル等低プラントル数流体の半ゾーン液体ブリッジにおける熱毛細管流の実験的研究
タイトル（掲載誌）宇宙開発事業団技術報告: Marangoni Convection Modeling Research: Annual Report April 1, 1999 - March 31, 2000 = NASDA Technical Memorandum: Marangoni Convection Modeling Research: Annual Report April 1, 1999 - March 31, 2000
一般注記Oscillatory thermocapillary flow of low Prandtl number fluid in the half-floating zone was experimentally studied under normal gravity. Measurement technique in surface temperature of a liquid bridge of tin as a test fluid was developed. Theoretical investigation of radiation energy from molten tin showed that PbS photo detector can measure proper wavelength range with high radiation energy, combined with use of CaF2 optical pass filter. It was confirmed that the selected radiation thermometer had temperature resolution that was smaller than amplitude of temperature fluctuation of oscillatory flow. The new measuring technique made it possible to observe surface temperature fluctuations successfully by using the ex-chamber in which CaF2 optical pass filter has not been installed. The periodic fluctuation continued approximately 100 sec, then damped gradually, suggesting that reduction in temperature dependence of 7.6 K was observed for onset of the periodic flow, which was almost good agreement with the numerical result with 7.1 K. It should be noted here the second bifurcation point, which has never observed yet, could be detected by the present experiments. Considerations for surface science of tin led to the design of unique experiment apparatus where clean surface of molten tin was able to obtain and sustain during an experiment. Ar(+) ion etching method was applied to remove residual surface oxides, and effectiveness of the etching was confirmed by the installed ion gun that was designed for surface cleaning. Prevention of further oxidation under vacuum condition of about 10(exp -6) Pa during one experiment was experimentally verified by in situ measurements of surface tension of molten tin. Novel visualization technique (3D-UV) of flow field measurements for liquid metals using ultrasonic transducer with high heat resistance is currently under development for the experiments. It was concluded that the first bifurcation point could be detected precisely by 3D-UV technique with the consideration of the experimentally predicted performances such as a resolution, a minimum size of a tracer, and a signal processing method. 3D-UV can visualize flow field of the liquid bridge in which the aspect ratio is a range of 2.3 (a = 1.5 mm) to 0.8 (a = 5 mm). The visualization technique requires development of unique balloon-like tracer also. It was confirmed that the balloon tracer with good sphericity could be actually manufactured by electroless plating of Ni over surface of Shirasu-balloon, which is an expanded volcanic particle, subsequently by electrolysis plating of Fe.
資料番号: AA0010763004
レポート番号: NASDA-TMR-000006E
連携機関・データベース国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）
提供元機関・データベース宇宙航空研究開発機構 : 宇宙航空研究開発機構リポジトリ