Influence of Liquid Viscosity and Column Diameter on Single Taylor Bubble Movement in a Stagnant Liquid Column

Resumo

The present paper reports an experimental study of single Taylor bubbles rising in vertical and slightly inclined tubes 2.0 m long, with inner diameters of 0.019, 0.024 and 0.034 m containing different stagnant mixtures of water and glycerin. A Taylor bubble with length L_b was formed by the inversion of the pipe partially filled with liquid to leave an air pocket of length L_0. The bubble velocities were measured by using a visualization technique with high speed video camera. Correlations available in the literature to estimate the bubble velocity and the influence of the Morton (M) and Eotvos (Eo) numbers on this parameter were evaluated for the range 1.17x10^-11 < M < 29.86 and 50 < Eo < 228. The results indicated that the bubble velocity tends to increase when the inclination angle increases and when M decreases. For all liquids studied, Eo has no influence on the bubble velocity, for 50 < Eo < 113. Increasing Eo (Eo > 159), the bubble velocity tends to increase, for lower viscosity liquids or M < 6.04x10^-8, however no influence of Eo on the bubble velocity was observed for the higher viscosity liquids or M > 1.86x10^-4. In general, all correlations evaluated can estimate the bubble velocities with relative errors smaller than 15%, for inclination angles between 0^o and 15^o