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Interfacial characteristics of stratified liquid–liquid flows using a conductance probe

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Abstract

In this paper, the characteristics of the interface in stratified oil–water flows and their changes during the transition to dual continuous flows were studied experimentally with a double-wire conductance probe. Experiments were carried out in an acrylic test section, 38 mm ID, using tap water and oil (ρ = 830 kg m−3 and μ = 0.0055 kg m−1 s−1) as test fluids. The boundaries between stratified and dual continuous flow were identified from high-speed imaging. A double-wire conductance probe, consisting of two 0.5 mm wires set 2 mm apart along a vertical pipe diameter, was used to obtain time records of the interface height in stratified flow. The probe was located either close to the test section inlet or at 7 m downstream the inlet, where the flow was fully developed. Data were collected for a period of 4 min at 256 Hz sampling frequency. A rigorous methodology was followed to treat the probe data and to estimate average parameters such as interface height with known accuracy and confidence intervals. The analysis ensured repeatability of the results. The procedure allowed accurate estimations of the power spectra of the probe signal and revealed the characteristic frequencies of the interface in stratified flow. It was found that the transition from stratified to dual continuous flow delayed to higher mixture velocities at input oil-to-water flow rate ratios, r, close to 1. At 7 m from the inlet, where the flow is fully developed, the interface was found to be fluctuating with three-dimensional characteristics for all conditions studied, while the oil-to-water velocity ratios, calculated from interfacial heights, were close to 1. The power spectra of the probe data showed peaks at low frequencies (1–3 Hz) that were attributed to the pumps. A range of high frequency contributions (between 10 and 40 Hz) appeared as the mixture velocity increased, which reflect the fluctuating nature of the interface. The relative intensity of these contributions increased with mixture velocity, and close to the transition to dual continuous flow, it became larger than that of the low-frequency contributions from the pumps. In contrast, close to the pipe inlet, for flow rate ratios different than one, waves appeared. These, however, died out further downstream.

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Abbreviations

A :

Cross-sectional area

A o, A w :

Area occupied by oil and water

b 0, b 1 :

Coefficients of linear regression

D :

Pipe diameter

f :

Frequency

f j :

Correction fraction

f s :

Sampling frequency

FFT:

Fast Fourier transform

h i :

Interface height

\(\bar{h}\) :

Total average interface height of all intervals

\(\bar{h}_{i}\) :

Average interface height of an interval

\(\bar{H}\) :

Time-averaged interface height

i, j :

Subscripts

k :

Discrete time delay

KH:

Kelvin–Helmholtz

m, m′, M, M′:

Number of intervals

m :

Number of degrees of freedom

n, n′, N, N′:

Number of data points

QCV:

Quick-closing valves

Q i :

Normalized parameter

Q o :

Oil flow rate

Q w :

Water flow rate

r :

Volume flow rate input ratio

r t,h :

Input ratio of highest mixture velocity at which transition occurs

R :

Mass flow rate input ratio

R yy (k):

Auto-correlation function (of the time delay) of data

Re :

Reynolds number

Re so, Re sw :

Superficial Reynolds number of oil and water

Re o, Re w :

Actual Reynolds number of oil and water

s, s′:

Standard deviations

S o, S w :

Wetted perimeter of oil and water

S i :

Length of the interface

t, T :

Time

t :

Percentile of the t distribution

u :

Velocity

U mix :

Mixture velocity

u so, u sw :

Superficial velocity of oil and water

u o, u w :

Actual velocity of oil and water

y :

Probe signal and data

y n :

n-Data point of probe signal

Y n :

De-trended n-data point of probe signal

y c :

Data point after correction factor

\(\bar{y}_{\text{w}}\) :

Interface height at 100 % water during the calibration

\(\tilde{y}_{n}\) :

Linear regression n-data point

α :

Level of significance

α w :

Water fraction

μ hi :

Mean of average interface height distribution

μ o, μ w :

Viscosity of oil and water

ν o, ν w :

Kinematic viscosity of oil and water

π :

Pi

ρ o, ρ w :

Density of oil and water

ρ r :

Relative density of oil respect to that of water

\(\sigma_{\text{hi}}^{2}\) :

Variance of average interface height distribution

Σ:

Summation

χ2 :

Chi-square distribution

Δt :

Sampling time

ω hi :

Absolute uncertainty of interface height

References

  • Alamu MB, Azzopardi BJ (2011) Flow pattern and slug dynamics around a flow splitter. J Fluids Eng 133(12):121105

    Article  Google Scholar 

  • Al-Wahaibi T (2006) Investigations on the transition between stratified to non-stratified horizontal oil–water flows. PhD dissertation, University College London

  • Al-Wahaibi T, Angeli P (2011) Experimental study on interfacial waves in stratified horizontal oil–water flow. Int J Multiph Flow 37(8):930–940

    Article  Google Scholar 

  • Andritsos N (1992) Statistical analysis of waves in horizontal stratified gas–liquid flow. Int J Multiph Flow 18(3):465–473

    Article  MATH  Google Scholar 

  • Azzopardi BJ (1986) Disturbance wave frequencies, velocities and spacing in vertical annular two-phase flow. Nucl Eng Des 92:121–133

    Article  Google Scholar 

  • Azzopardi BJ (1997) Drops in annular two-phase flow. Int J Multiph Flow 23(7):1–53

    Article  Google Scholar 

  • Bai R (1995) Traveling waves in a high viscosity ratio and axisymmetric core annular flow. PhD dissertation, University of Minnesota

  • Bannwart AC (1998) Wavespeed and volumetric fraction in core annular flow. Int J Multiph Flow 24(6):961–974

    Article  MATH  Google Scholar 

  • Bendat JS, Piersol AG (2010) Random data: analysis and measurement procedures. Wiley, New Jersey

    Book  Google Scholar 

  • Brauner N, Moalem Maron D (1989) Two phase liquid–liquid stratified flow. Phys Chem Hydrodyn 11(4):487–506

    Google Scholar 

  • Chakrabarti DP et al (2006) The transition from water continuous to oil continuous flow pattern. AIChE J 52(11):3668–3678

    Article  Google Scholar 

  • Chu KJ (1973) Statistical characterization and modelling of wavy liquid films in vertical two-phase flow. PhD dissertation, University of Houston

  • De Castro MS et al (2012) Geometrical and kinematic properties of interfacial waves in stratified oil–water flow in inclined pipe. Exp Therm Fluid Sci 37:171–178

    Article  Google Scholar 

  • Drahos J, Ruzicka MC (2004) Problems of time series analysis in characterization of multiphase flows. Presented at the 5th international conference on multiphase flow 2004, Yokohama, Japan, May 30–June 4. Paper No. K04

  • Du M et al (2012) Time-frequency analysis of vertical upward oil–water two-phase flow. Presented at the 7th international symposium on measurement techniques for multiphase flows, AIP Conf Proc 1428:107–114

  • Fossa M (1998) Design and performance of a conductance probe for measuring liquid fraction in two-phase gas–liquid flows. Flow Meas Instrum 9(2):103–109

    Article  Google Scholar 

  • Hernández L et al (2006) Fast classification of 2-phase flow regimes based on conductivity signals and artificial neural networks. Meas Sci Technol 17:1511–1521

    Article  Google Scholar 

  • Jana AK et al (2006) A novel technique to identify flow patterns during liquid–liquid two-phase upflow through a vertical pipe. Ind Chem Eng Res 45(7):2381–2393

    Article  Google Scholar 

  • Jin ND et al (2003) Characterization of oil/water two-phase flow patterns based on non-linear time series analysis. Flow Meas Instrum 14:169–175

    Article  Google Scholar 

  • Juliá JE et al (2005) Objective fast local flow regime identification using conductivity probe and neural network techniques. Proceedings 11th international topical meeting on nuclear reactor thermal-hydraulics (NURETH-11), Avignon, France

  • Jurman L et al (1989) Periodic and solitary waves on thin, horizontal, gas–sheared liquid films. Int J Multiph Flow 15(3):371–384

    Article  Google Scholar 

  • Kadri U et al (2009) Prediction of the transition from stratified to slug flow or roll-waves in gas–liquid horizontal pipes. Int J Multiph Flow 35(11):1001–1010

    Article  Google Scholar 

  • Kim S et al (2000) Development of the miniaturized four-sensor conductivity probe and the signal processing scheme. Int J Heat Mass Transfer 43:4101–4118

    Article  MATH  Google Scholar 

  • Kumara WAS et al (2009) Pressure drop, flow pattern and local water volume fraction measurements of oil–water flow in pipes. Meas Sci Technology 20:114004

    Article  Google Scholar 

  • Kumara WAS et al (2010) Single-beam gamma densitometry measurements of oil–water flow in horizontal and slightly-inclined pipes. Int J Multiph Flow 36:467–480

    Article  Google Scholar 

  • Laflin GC, Oglesby KD (1976) An experimental study on the effects of flow rate, water fraction and gas-liquid ratio on air-oil-water flow in horizontal pipes. BSc Thesis, University of Tulsa

  • Li YW et al (2007) Design and performance of a six-electrode conductance probe for measuring the water fraction in oil-in-water pipe flow. Presented at the 8th international conference on electric measurements and instruments, Conf Proc 4:481–487

  • Lovick J (2003) Horizontal, oil–water flows in the dual continuous flow regime. PhD dissertation, University College London

  • Lovick J, Angeli P (2004) Experimental studies on the dual continuous flow pattern in oil–water flows. Int J Multiph Flow 30(2):139–157

    Article  MATH  Google Scholar 

  • Nädler M, Mewes D (1997) Flow-induced emulsification in the flow of two immiscible liquids in horizontal pipes. Int J Multiph Flow 23(1):55–68

    Google Scholar 

  • Oliemans RVA (1986) The lubricating-film model for core-annular flow. PhD dissertation, Delft University

  • Panagiotopoulos N, Lucas GP (2007) Simulation of a local four-sensor conductance probe using a rotating dual-sensor probe. Meas Sci Thecnol 18(8):2563–2569

    Article  Google Scholar 

  • Rodriguez OMH, Bannwart AC (2006) Analytical model for interfacial waves in vertical core flow. J Pet Sci Eng 54(3–4):173–182

    Article  Google Scholar 

  • Sawart P et al (2008) Properties of disturbance waves in vertical annular two-phase flow. Nucl Eng Des 238(12):3528–3541

    Article  Google Scholar 

  • Scott GM (1985) A study of two-phase liquid-liquid flow at variable inclinations. MSc Thesis, University of Texas

  • Sun B et al (2011) Time-frequency spectral analysis of gas–liquid two-phase flow’s fluctuations. Acta Phys Sin 60(1):014701

    Google Scholar 

  • Trallero JL (1995) Oil–water flow patterns in horizontal pipes. PhD dissertation, University of Oklahoma

  • Tsochatzidis NA et al (1992) A conductance probe for measuring liquid fraction in pipes and packed beds. Int J Multiph Flow 18(5):653–667

    Article  MATH  Google Scholar 

  • Valle A, Kvandal H (1995) Pressure drop and dispersions characteristics of separated oil-water flow. Presented at the international symposium on two-phase flow modelling and experimentation, Rome, Italy

  • Wang Z et al (2004) The influences of wave height on the interfacial friction in annular gas–liquid flow under normal and microgravity conditions. Int J Multiph Flow 30(10):1193–1211

    Article  MATH  Google Scholar 

  • Wang Z et al (2010) Non-linear dynamical analysis of large diameter vertical upward oil-gas-water three-phase flow pattern characteristics. Chem Eng Sci 65(18):5226–5236

    Google Scholar 

  • Webb D (1970) Studies of the characteristics of downward annular flow two-phase flow. PhD dissertation, University of Cambridge

  • Wu Q, Ishii M (1999) Sensitivity study on double-sensor conductivity probe for the measurement of interfacial area concentration in bubbly flow. Int J Multiph Flow 25:445–453

    Article  Google Scholar 

  • Xie T (2004) Hydrodynamic characteristics of gas/liquid/fiber three-phase flows based on objective and minimally-intrusive pressure fluctuation measurements. PhD dissertation, Georgia Institute of Technology

  • Xu W et al (2012) Normalized least-square method for water hold-up measurements in stratified oil–water flow. Flow Meas Instrum 27:71–80

    Article  Google Scholar 

  • Zhai L et al (2012) The development of a conductance method for measuring liquid hold-up in horizontal oil–water two-phase flows. Meas Sci Technol 23(2):025304

    Article  Google Scholar 

Download references

Acknowledgments

The authors are grateful to Chevron Technology Company and UCL for their financial support of this project. Special acknowledgments go to Dr. Valentina Dore for her review of the statistical procedure and her suggestions and to Dr. Simon Barrass for assisting technically with the conductance probe and instrumentation. The authors would also like to acknowledge the UK Engineering and Physical Sciences Research Council (EPSRC) for the loan of the high-speed camera Phantom Miro 4.

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Authors and Affiliations

  1. Department of Chemical Engineering, University College London, London, UK

    A. H. Barral & P. Angeli

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  1. A. H. Barral
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  2. P. Angeli
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Correspondence to P. Angeli.

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Barral, A.H., Angeli, P. Interfacial characteristics of stratified liquid–liquid flows using a conductance probe. Exp Fluids 54, 1604 (2013). https://doi.org/10.1007/s00348-013-1604-5

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