National Aerospace Laboratory
National Aerospace Laboratory
Nissan Motor Co Ltd Aerospace Division
Nissan Motor Co Ltd Aerospace Division
Nissan Motor Co Ltd Aerospace Division
National Space Development Agency of Japan
Japan Space Utilization Promotion Center
出版者
宇宙開発事業団
出版者（英）
National Space Development Agency of Japan (NASDA)
In microgravity, the familiar convection due to specific gravity difference disappears and the convection due to surface tension distribution (Marangoni convection) takes place. In the field of material processing, this flow disturbs the uniform crystal growth and ends in a random distribution of concentration. The importance of developing methods of in-situ observation of Marangoni flow has been recognized, and this is the main objective of this study. In the sounding rocket TR-1A (Test Rocket-1A), the method of two-dimensional observation inside a liquid bridge has been developed. But in chaos flow, three-dimensional observation from multiple directions becomes necessary. Moreover, tracers in a liquid column barely goes in the proximity of the free surface, and this leads to the necessity of developing a method of measuring surface flow. As the surface tension is determined by the temperature of free surface, the way of nontouch measurement of surface temperature is also in demand. In this study, the following in-situ observation techniques were carried out: (1) three dimensional observation using two independent CCD (Charge Coupled Device) cameras; (2) observation using high speed rate camera; (3) measurement of temperature of the liquid column using infrared camera; and (4) observation of photochromism driven by ultra-violet ray or pulse laser. The following results were obtained: (1) the two contacting liquids exchange the heat very slowly; (2) the bare contact of the two silicone-oil balls didn't cause the formation of a liquid bridge. The placing of a needle was needed; (3) the temperature inside the liquid bridge (if formed) is normalized quickly; (4) in case of water and ethyl alcohol contact, the quick averaging of the temperature due to Marangoni convection takes place. The study of the observed vibration of the whole liquid column is undergoing; (5) the visualization of the surface flow by photochromism due to the ultraviolet-ray absorption, needs a further study; and (6) the visualization of the flow by photochromism driven by pulse laser is already in the good level for utilization.
マランゴニ対流観察実験
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