University of Toronto Dept. of Chemical Eng. and Applied Chem.
University of Toronto Dept. of Chemical Eng. and Applied Chem.
University of Toronto Dept. of Chemical Eng. and Applied Chem.
著者所属（英）
University of Toronto Department of Chemical Engineering and Applied Chemistry
University of Toronto Department of Chemical Engineering and Applied Chemistry
University of Toronto Department of Chemical Engineering and Applied Chemistry
出版者
宇宙開発事業団
出版者（英）
National Space Development Agency of Japan (NASDA)
An experimental investigation has been conducted on Marangoni convection in liquid bridges of 7 mm diameter with acetone (Pr = 4.3) and 5 cSt silicone oil (Pr = 67) to investigate the temperature oscillation characteristics and the effects of small horizontal vibrations on the onset of oscillatory flow and surface dynamics. For acetone, the temperature oscillation frequency increased nearly linearly with the disk temperature difference, but inversely with the aspect ratio. For the partially open system, the oscillation frequencies were about 20 percent greater than those determined for the closed system at the same Delta-T. The variation of the temperature oscillation frequency with Delta-T was in qualitative agreement with that predicted previously by a numerical simulation. Vibration experiments were conducted with acetone, water and silicone oil bridges, by applying horizontal vibrations of different amplitudes and frequencies. For an isothermal water bridge, the surface oscillation amplitude was found to be strongly dependent on the volume ratio of the liquid bridge, and the oscillation frequency was much larger than the frequency of the vibrations applied. A previous vibration model for a straight cylinder was modified to predict the vibration frequency of a hyperboloid-shaped liquid bridge. The predictions of the modified model showed qualitative agreement with the measurements. For acetone and silicone oil bridges, vibrations of different amplitudes and frequencies were applied to determine their effects on the critical temperature difference. For increasing the temperature difference, ramp and step increase methods were used for acetone and silicone oil bridges, respectively. For a vibrating liquid bridge, a step increase method was found to be more appropriate for obtaining more accurate critical Delta-T data. The critical temperature difference was then measured for acetone and silicone oil bridges vibrated at different acceleration levels, but no apparent effect of vibration could be observed on the critical temperature difference in the ranges of variables covered. The response of the liquid bridge surface was also recorded by a video camera and the surface motion was analyzed for different volume and aspect ratios. Greater amplitudes of surface vibration were measured when the disk temperature difference was greater than the critical value compared to an isothermal liquid bridge. The surface oscillation amplitude was also found to increase with the distance below the hot corner.
Investigation of horizontal vibrations on Marangoni convection in a liquid bridge
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