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ISSN Online: 2377-424X

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

On the Wake Effect in Bubble Rising Velocity for One-Component Systems

Get access (open in a dialog) DOI: 10.1615/IHTC12.2590
6 pages

Sinopsis

The present paper reports about an experiment of bubble rising velocity in a liquid column using R-114 and FC- 72. Vapour bubbles are generated at the bottom of the saturated liquid column by a tiny electric heater and their evolution is recorded with high speed cinematography from the generation point until they reach the terminal velocity in the liquid column.
Single bubble and bubble train (with controlled frequency) tests are carried out to ascertain the wake effect on the bubble rising velocity in the range of diameters from 0.1 to 0.8 mm, showing a negligible effect of the wake effect for the tested bubble diameters.
Prediction of bubble terminal velocity with available correlations turns out to be not very successful, as all available models and correlations are developed for two-component systems (gas and liquid). A recent expression for the drag coefficient, specifically derived for single bubbles in infinite stagnant liquids under surface tension dominant regime, looks promising although the agreement with present experimental data is not completely satisfactory.