Falling film hydrodynamics in slug flow

Ahmad, W.; DeJesus, J.M.; Kawaji, Masahiro

doi:10.1016/s0009-2509(97)00276-5

Cited by 32 publications

(13 citation statements)

References 9 publications

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“…The axial locations of the onset and termination of the reverse¯ow were close to those measured by Nakoryakov et al (1986Nakoryakov et al ( ,1989. DeJesus et al (1995), Kawaji et al (1997) and Ahmad et al (1998) applied the photochromic dye activation method to measure the¯ow ®eld around a bubble rising in stagnant liquid (kerosene). The instantaneous velocity distributions in front of the bubble, in the liquid ®lm and in the near wake were visualized.…”

Section: International Journal Of Multiphase Flow 25 (1999) 957±975mentioning

confidence: 52%

The relation between the Taylor bubble motion and the velocity field ahead of it

Polonsky

Shemer

Barnea

1999

International Journal of Multiphase Flow

132

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This paper is dedicated to Professor Gad Hetsroni on the occasion of his 65th birthday. Gad, through his leadership and devotion to science in general and multiphase¯ows in particular, has been the beacon of this ®eld. As the Founder and the Editor of the International Journal of Multiphase Flow, Gad has marched this ®eld forward at a rapid pace and positioned it at the focus of science and engineering. We would like to express our deep gratitude to Gad for all he has done for the ®eld of multiphase¯ow and we wish him many more productive and enjoyable years. AbstractThe motion of a single elongated (Taylor) bubble propagating in a transparent vertical pipe is studied experimentally in stagnant liquid, as well as in upward and downward liquid¯ow. Digital image processing of a sequence of video images serves as the main experimental method for the study of the Taylor bubble motion. In addition, the distribution of the velocities in front of the bubble and in the liquid ®lm is measured using Particle Image Velocimetry. The relation between the Taylor bubble motion and the velocity ®eld in front of it is discussed. #

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Section: International Journal Of Multiphase Flow 25 (1999) 957±975mentioning

confidence: 52%

The relation between the Taylor bubble motion and the velocity field ahead of it

Polonsky

Shemer

Barnea

1999

International Journal of Multiphase Flow

132

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“…These velocities attain values of approximately 1 m/s at the exit from the film. For bubble lengths of about 3.6D studied here, the film velocity is below the terminal value of a Ahmad et al (1998) and Polonsky et al (1999b).…”

Section: Mean Velocity Profilesmentioning

confidence: 74%

“…Measurements of flow field parameters around elongated bubbles in pipes are sparse (Kvernvold et al, 1984;Nakoryakov et al, 1986Nakoryakov et al, , 1989Shemer and Barnea, 1987;DeJesus et al, 1995;Kawaji et al, 1997;Ahmad et al, 1998;Polonsky et al, 1999b). Kvernvold et al (1984) performed velocity measurements in horizontal slug flow using Laser Doppler Velocimetry.…”

Section: Introductionmentioning

confidence: 99%

“…The observed velocity profile was highly distorted in the near wake of the bubble and seemed to be fully developed at approximately 12D from the tail of the bubble. Ahmad et al (1998) applied a photochromic dye activation technique to measure the instantaneous velocity profiles in the near wall region around individual and coalescing pairs of Taylor air bubbles rising in a 25.6 mm ID tube filled with stagnant kerosene. At approximately 2D behind the bubble tail, large vortices decayed and the flow tended to become stagnant again.…”

Section: Introductionmentioning

confidence: 99%

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Experimental investigation of the velocity field induced by a Taylor bubble rising in stagnant water

Hout

Gulitski

Barnea

et al. 2002

International Journal of Multiphase Flow

101

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An experimental investigation of the flow field around a single Taylor bubble rising in a vertical pipe filled with stagnant water is presented. The Reynolds number of the flow based on the Taylor bubble rise velocity and the pipe diameter is 4350. The velocity field around the bubble was determined by Particle Image Velocimetry (PIV). The mean velocity fields in front of the bubble, in the liquid film, and in the wake region were calculated by ensemble-averaging the instantaneous velocity fields measured around 100 different bubbles. Ensemble-averaged velocities become negligible at 0.5D from the bubble nose and at $12 D from the bubble tail. However, notable instantaneous velocity fluctuations were found to exist up to 50D from the Taylor bubble tail. These residual vortices may influence the shape and the propagation velocity of the trailing bubble even at large separation distances. Ó

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“…The observed velocity profile was highly distorted in the near wake of the bubble; the profile appeared to be fully developed at about 12D from the bubble tail. Ahmad et al (1998) applied a photochromic dye activation technique to measure the instantaneous velocity profiles in the near wall region around individual and coalescing pairs of Taylor bubbles. Recent results obtained in experiments with controlled bubble injection in our laboratory are presented in the sequel.…”

Section: Hydrodynamics Of the Liquid Slug--experiments With Controllementioning

confidence: 99%

Hydrodynamic and statistical parameters of slug flow

Shemer

2003

International Journal of Heat and Fluid Flow

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In two-phase slug flow pattern, the bulk of the gas is trapped inside large bubbles that are separated by liquid slugs, which may contain small dispersed bubbles. The unsteady nature of slug flow makes the prediction of pressure drop and heat and mass transfer a difficult task. Earlier models that deal with steady slug flow assume constant lengths and shapes of liquid slugs and elongated bubbles, as well as a constant elongated bubble propagation velocity. However, due to the intrinsically irregular character of slug flow, statistical means are required for its proper description. Variation of the flow parameters along the pipes of various diameters and inclinations may strongly affect the resulting flow pattern and should thus be taken into account in modeling the flow. The development of slug flow along the pipe is mainly governed by the interaction between consecutive elongated bubbles. To gain a better insight into the mechanisms that govern slug flow evolution along pipes, experiments with controlled injection of consecutive elongated bubbles were performed in recent years. Due to the complexity of both the continuous slug flow and the liquid flow around injected bubbles, sophisticated experimental methods are required. The latest works regarding the hydrodynamic and statistics of naturally occurring continuous slug flow in pipes, as well as the results of experiments with controlled injection of elongated bubbles are reviewed. It is demonstrated how the information obtained in the controlled experiments can be applied to improve the performance of slug flow and slug tracking models.

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Falling film hydrodynamics in slug flow

Cited by 32 publications

References 9 publications

The relation between the Taylor bubble motion and the velocity field ahead of it

The relation between the Taylor bubble motion and the velocity field ahead of it

Experimental investigation of the velocity field induced by a Taylor bubble rising in stagnant water

Hydrodynamic and statistical parameters of slug flow

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