The present paper reports an experimental study of single Taylor bubbles rising in vertical and slightly deviated tubes (θ < 15o) containing different stagnant mixtures of water and glycerin. The bubble shapes or its contours at two vertical orthogonal planes that intersect at the tube axis and the bubble velocities were measured by using a non-intrusive pulse-echo ultrasonic technique. The use of four ultrasonic transducers made it possible to observe the liquid film draining not only at the top and at the bottom of the bubbles, but also at their lateral sides, which allowed an experimental verification of the liquid film integrity at these radial positions and of the lateral symmetry of the bubbles. Based on the velocity measurements, the influence of liquid properties and of tube diameter on the bubble movement and shape were evaluated for inclinations ranging from 0o to 15o from the vertical. Finally, the performance of different correlations to predict the drift velocity were tested for this particular range of inclination.
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