Experimental study of single Taylor bubbles rising in vertical and slightly deviated circular tubes

• Published in: Experimental thermal and fluid science 2020-08, Vol.116, p.110109, Article 110109
• Main Authors: de Azevedo, Marcos B., Faccini, José L.H., Su, Jian
• Format: Article
• Language: English
• Subjects: Bubble shape; Bubble velocity correlations; Bubbles; Circular tubes; Diameters; Drainage measurement; Inclination angle; Orthogonality; Slightly deviated tubes; Stagnant liquid; Stagnant water; Taylor bubble; Taylor bubbles; Ultrasonic methods; Ultrasonic technique; Velocity
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/j.expthermflusci.2020.110109

•Shape and velocity of Taylor bubbles rising in deviated tubes was measured.•A pulse-echo ultrasonic technique was used for measurements.•Inclination angles ranging from 0 to 15 degrees from the vertical.•Morton numbers ranging from 1.17 × 10−11 to 29.86.•Correlations for bubble velocity were evaluated. This paper reports an experimental study of single Taylor bubbles rising in stagnant water-glycerin mixtures inside slightly deviated cylindrical tubes. The inclination angles studied were 0°, 2.5°, 5°, 7.5°, 10° and 15° from the vertical. The rise bubble velocity and the shape of the bubbles at two vertical orthogonal planes that intersect at the tube axis were measured by using a pulse-echo ultrasonic technique. Thus, the liquid films draining at the top, bottom and lateral sides of the bubbles were observed. The experimental results indicated that for all liquid mixtures studied, the bubble velocity increased when the inclination angle was increased, and that the bubble velocity was independent of the bubble length. The influence of liquid properties and of tube diameter on the bubble movement and shape were evaluated for deviated angles ranging from 0° to 15°. Different correlations to predict the drift velocity of Taylor bubbles rising in inclined tubes were tested for this particular range of inclination.