Velocity distribution in horizontal slug flow

1999

132

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. #

Section: Velocity Of the Liquid In The ®Lmsupporting

confidence: 91%

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

confidence: 99%

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

Polonsky

Shemer

1999

132

“…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%

“…Kvernvold et al (1984) performed velocity measurements in horizontal slug flow using Laser Doppler Velocimetry. The length of the wake region increased with increasing Reynolds number (Re) based on the mixture velocity.…”

Section: Introductionmentioning

confidence: 99%

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

Hout

Gulitski

et al. 2002

100

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

“…The predicted stable slug length was in a good agreement with experimental results. Kvernvold et al (1984) used LDV-technique for measuring velocity pro®les in the liquid slug and in the ®lm region of a horizontal slug¯ow. Nakoryakov et al (1989) performed a more extensive study of an instantaneous velocity ®eld in a vertical¯ow using an electrochemical velocity probe.…”

Section: Introductionmentioning

confidence: 99%

Averaged and time-dependent characteristics of the motion of an elongated bubble in a vertical pipe

Polonsky¹,

Shemer

1999

The motion of elongated (Taylor) bubbles in air±water vertical¯ow is studied by processing consecutive series of digitized video images. The shape of the elongated bubbles, as well as the velocities of the liquid±gas interfaces, are measured for various¯ow conditions. The bubble velocity variation caused by air expansion under the in¯uence of hydrostatic pressure gradient is measured and compared with model predictions. An oscillatory motion of the bubble bottom is observed. The frequency and the amplitude of these oscillations are studied as a function of bubble length and water¯ow rate. This information is essential for accurate modeling of developing gas±liquid slug¯ow. #