@techreport{oai:jaxa.repo.nii.ac.jp:00002357, author = {松本, 聡 and 林田, 均 and 小宮, 敦樹 and 夏井, 秀定 and 依田, 真一 and Matsumoto, Satoshi and Hayashida, Hitoshi and Komiya, Atsuki and Natsui, Hidesada and Yoda, Shinichi}, month = {Mar}, note = {The experimental study on thermocapillary convection of low Prandtl number fluid was carried out to understand transition behavior to oscillatory flow. The half-zone liquid bridge of molten tin was formed between hot and cold disks in high vacuum chamber (10(exp -5) Pa). The three radiation thermometers were used to measure the free surface temperature at a different azimuthal location at the same time. In addition, the temperature distribution at interface between liquid bridge and cold disk was measured by using very fine thermocouples. In order to detect the transition point and to make clear the oscillation mode more precisely, the temperature measurement system was developed. It could be detected that the steady thermocapillary convection changes to oscillatory under certain condition. The observed phenomena of transition processes after the oscillatory onset were revealed by comparing to numerical result done by Imaishi et al. The effect of aspect ratio (L/r) on critical Marangoni number was investigated. The critical Marangoni number decreases with increasing the aspect number. This behavior agrees with numerical simulation done by Imaishi et al. qualitatively except for region of smaller aspect ration. Since the echo signal from the tracer had the very small bad SN ratio, in order to raise the SN ratio, signal processing technique was examined. Consequently, the noise which originates in the shoe by the subtraction processing technique was removable. And the SN ratio could be improved by the addition processing by repetition measurement, and the SN ratio improved about three times by calculation supposing actual measurement. The A/D converter and the system controller were manufactured in the 3D-UV measurement unit., 資料番号: AA0048708006, レポート番号: JAXA-RR-04-027E}, title = {Experimental study of thermocapillary flow in the half-zone liquid bridge of low Prandtl number fluid}, year = {2005} }