Analysis of Horizontal Air-Silicone Oil Plug-To-Slug Transition Flow

Filed in Articles by on July 18, 2022

Analysis of Horizontal Air-Silicone Oil Plug-To-Slug Transition Flow.


The analysis of the experimental data for the air-silicone oil plug-slug transition in a 67mm id and 6m long horizontal pipe was carried out in this work.

The superficial gas and liquid velocity ranged from (0.05 – 4.73) m/s and (0.05 – 0.473) m/s respectively. The transition from plug to slug flow was investigated by increasing the superficial gas velocity at fixed superficial liquid velocity.

For the investigated experimental data set, the intermittent flow was observed at the superficial liquid velocity of 0.142m/s. The transition from plug to slug flow for the experimental data was observed at the superficial velocity of between 0.7 – 1.2m/s.

To characterize the plug – slug transition, the effect of liquid and gas superficial velocity on void fraction, bubble velocity, bubble length and slug frequency were obtained.

The drift flux model for the data set was also obtained and compared with existing models for horizontal flow. The results obtained from the analysis agree well with the reports of several literatures for the air – water plug – slug transition in horizontal pipes.




1.1 Introduction …. 8
1.2 Characterization of two-phase flow ….. 8
1.3 Plug-slug transition in horizontal flow ……. 10
1.4 Problem Statement ……. 11
1.5 Aim and Objectives of the Research …….. 11
1.6 Organization of the Research …. 11


2.1 Flow regimes classification in two-phase flow ….. 13
2.2 Horizontal flow regime… 14
2.2.1 Bubbly flow: ………… 14
2.2.2 Plug Flow: …… 14
2.2.3 Stratified Flow: .. 14
2.2.4 Wavy Flow: ……. 14
2.2.5 Slug flow: ……….. 15
2.2.6 Annular Flow: .. 15
2.3 Vertical Flow Regimes ………. 15
2.3.1 Bubbly Flow: …. 15
2.3.2 Slug Flow: ……… 16
2.3.3 Churn Flow: …….. 16
2.3.4 Annular Flow: …… 16
2.4 Parameters to characterize flow regimes ……… 17
2.4.1 Void Fraction …… 17
2.5 Flow Pattern Map …….. 18
2.5.1 Flow pattern map for Horizontal flow .18
2.6 Flow pattern identification using PDF ……. 22
2.7 Flow pattern Transition….. 24
2.7.1 Experimental study of horizontal air-water plug-to-slug transition flow in different pipe sizes  25
2.7.2 Experimental investigation of horizontal air–water bubbly-to-plug and bubbly to-slug transition flows in a 3.81 cm ID pipe ….26
2.7.3 Transition of plug to slug flow and associated fluid dynamics .. 28
2.7.4 Characterization of horizontal air–water two-phase flow ……. 29
2.7.5 Horizontal two-phase flow pattern recognition …… 30
2.7.6 Intermittent flow parameters from void fraction analysis ….. 31


3.1 Data Acquisition ……… 32
3.2 Data Processing ……… 32
3.3 Flow regime identification using flow pattern map, time series analysis and PDF 33
3.4 Analysis of the acquired data: …. 34


4.1 Flow Regime Identification ….. 36
4.2 Effect of Gas and Liquid superficial velocity on Void fraction …….. 40
Figure4. 4 Effect of increasing gas and liquid superficial velocity (0.142-0.473 m/s) on void fraction 40
4.3 Effect of Mixture Velocity on Bubble Velocity ….. 41
4.4 Drift Flux Analysis ….. 42
4.5 Effect of Gas and Liquid Superficial velocity on Bubble length .. 44
4.6 Effect of Gas and Liquid Superficial Velocity on Bubble Velocity …. 45
4.7 Variation of frequency as a function of Gas and Liquid Superficial velocity ……… 46


REFERNCES ………….. 50


Two-phase flow occurs when two different fluids move concurrently through a pipe. The exact form of two-phase flow is determined according to the phases appearing in the mixture, namely solid-liquid, gas-solid (e.g. particles in a gas or liquid) and gas-liquid (droplets in gas and gas bubbles in a liquid)(Gschnaidtner, 2015).

The study of two-phase flows is of great importance for several technological applications.

Particularly, gas-liquid two-phase flows are often encountered in a wide range of industrial applications, such as condensers, evaporators, distillation towers, nuclear power plants, boilers, crude oil transportation and chemical plants among others.

Gas-liquid flow is not only the most common of the two-phase flows; it is also the most complex since it combines the characteristics of a deformable interface with those of a compressible phase (Carpintero, 2009).


Abdulkadir, M., Hernandez-Perez, V., Lowndes, I. S., Azzopardi, B. J., & Sam-Mbomah, E. (2016). Experimental study of the hydrodynamic behaviour of slug flow in a horizontal pipe.
Chemical Engineering Science, 156, 147–161. Abdulkadir, Mukhtar. (2011). Department of Chemical and Environmental Engineering Experimental and Computational Fluid Dynamics ( CFD ) Studies of Gas-Liquid Flow in Bends By Mukhtar Abdulkadir , BEng , MSc Thesis submitted to the University of Nottingham for the degree of Doctor of. 262(August).
Abdulmouti, H. (2014). Bubbly Two-Phase Flow: Part I- Characteristics, Structures, Behaviors and Flow Patterns. American Journal of Fluid Dynamics, 4(4), 194–240. Bendiksen, K. H. (1984).
AN EXPERIMENTAL INVESTIGATION OF THE MOTION of long bubles in inclined tubes. Int. J. Multiphase Flow, 10(4), 467–483. Benjamin, T. B. (1968).
Gravity currents and related phenomena. Journal of Fluid Mechanics, 31(02), 209–248. Carpintero, E. (2009). Experimental Investigation of Developing Plug and Slug Flows. 138.
Retrieved from Costigan, G., & Whalley, P. B. (1997).
Slug flow regime identification from dynamic void fraction measurements in vertical air-water flows. International Journal of Multiphase Flow, 23(2), 263–282.

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