Movement of Two Consecutive Taylor Bubbles in Vertical Pipes

Abstract

Abstract. The development of slug flow along vertical pipes is governed by the interaction between consecutive elongated bubbles. It is generally assumed that the trailing bubble's shape and velocity are affected by the flow field in the liquid phase ahead of it. To examine this assumption, a facility is used that allows controlled injection of pairs of Taylor bubbles into vertical pipes filled with stagnant or flowing liquid. An experimental approach is developed to perform particle image velocimetry measurements of the velocity field in front of the trailing Taylor bubble, simultaneously with video imaging of Taylor bubble pairs, to be able to relate the instantaneous parameters (shape and velocity) of the trailing bubble to the instantaneous velocity distribution in liquid ahead of it. Experiments are performed in pipes of two diameters and for a number of Reynolds numbers based on mean water velocity, corresponding to both laminar and turbulent background flows. A model relating the propagation velocity of the trailing Taylor bubble to the local mean centerline velocity of the leading bubble is suggested and verified experimentally. The effect of the velocity fluctuations in the leading Taylor bubble's wake on the instantaneous propagation velocity of the trailing bubble is studied. 2 SHEMER, GULITSKI and BARNEA

Investigation of Taylor bubble wake structure in liquid nitrogen by PIV technique

“…A great amount of investigations have been devoted to the flow structure in Taylor bubble wake in water or water-based two-phase flow [24,4,[19][20][21]25,26], among others. Campos and Guedes de Carvalho [4] conducted a photographic study of the wakes of Taylor bubbles rising in stagnant water and aqueous glycerol solutions in the tubes of 19 mm and 52 mm internal diameter.…”

“…As a non-invasive flow sensing methods, particle image velocimetry (PIV) was widely adopted to investigate the flow field around Taylor bubble in ordinary liquid [3,22,29,27,15,16,25,26]. PIV technique has already been used for investigating the flow field of cryogenic fluid [17,18,13,14,31,8].…”

A method to reduce the computational cost of CFD simulations of vertical slug flows

“…In their experimental work, Shemer et al (2007) also obtained a smaller velocity for the trailing bubble (in relation to the leading one) if l l,t > 7D, for both the laminar and turbulent scenarios. Taitel et al (1980), while working on the transition between the churn and the (continuous) slug patterns in vertical flows, adopted an exponential decay for the centerline velocity, departing from V c = V tb in the end of the leading TB to V c = 1.2 V l at the end of a stable liquid slug (with l ls = 16D).…”

“…A trail of bubbles is formed under these conditions, and the liquid separating the elongated bubbles has the presence of small gas bubbles. In this scenario only the first bubble necessarily follows the rising velocity of a single bubble (obtained according to Nicklin et al (1962)); the trailing bubbles (usually) move faster than the first one (Pinto and Campos, 1996;Shemer et al, 2007;Morgado et al, 2016).…”