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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Effects of surface evaporation on temperature oscillation frequency and surface flow in Marangoni Convection of an intermediate Prandtl number fluid

Get access (open in a dialog) DOI: 10.1615/IHTC12.2550
6 pages

Résumé

The effects of evaporation on thermocapillary convection instability were investigated in half floating zones of acetone (Pr = 4.3). The half-zones were 7.0 mm in diameter and either fully enclosed with a quartz tube or partially open to the ambient air, to change the evaporation rate. The experimental results showed that surface evaporation does not significantly affect temperature oscillation frequency. Although the evaporation rates of acetone were 400-500 percent higher when the system was partially open than when it was closed, the frequencies in the partially open system were only about 20 percent higher than the corresponding frequencies in the closed system at the same temperature differences between the upper hot disk and lower cold disk. When non-dimensionalized, the experimental results showed good agreement with Leypoldt et al.'s (2000) numerical simulation predictions, as well as Preisser et al.'s (1983) data. Under relatively high evaporation rates in the partially open half-zones, a constant azimuthal velocity component was found to exist even in steady flow. This unexpected result may indicate possible similarities between the instability mechanisms which prevail in intermediate Pr half-zones and molten metals of low Prandtl number.