Experiments have been carried out to analyze the evolution of the air/water flow structure along a horizontal 60 mm i.d. straight pipe. Plug and slug flow regimes were observed. In order to investigate the local structure of the flow, dynamic void fraction measurements have been performed by means of ring impedance probes. From dynamic void fraction measurements the mean void fraction values, the probability distributions of void, the liquid film height in the gas cavities and the slug frequencies have been evaluated. The analysis of the results showed that the flow structure deeply modifies along the pipe and that minor effects have to be ascribed to gas injection mode. The examination of the probability distribution function enabled the identification of the operating conditions at which the transition occurs, thus making it possible to propose a new objective criterion of identification.

1.
Dukler
,
A.
, and
Hubbard
,
M. G.
,
1975
, “
A Model for Gas-Liquid Slug Flow in Horizontal and Near Horizontal Tubes
,”
Ind. Eng. Chem. Fundam.
,
14
, pp.
337
347
.
2.
Nicholson
,
M. K.
,
Aziz
,
K.
, and
Gregory
,
G. A.
,
1978
, “
Intermittent Two Phase Flow in Horizontal Pipes: Predictive Models
,”
Can. J. Chem. Eng.
,
56
, pp.
653
663
.
3.
Andreussi
,
P.
,
Bendiksen
,
K. H.
, and
Nydal
,
O. J.
,
1993
, “
Void Distribution in Slug Flow
,”
Int. J. Multiphase Flow
,
19
, pp.
817
828
.
4.
Andreussi
,
P.
,
Minervini
,
A.
, and
Paglianti
,
A.
,
1993
, “
Mechanistic Model of Slug Flow in Near Horizontal Pipes
,”
AIChE J.
,
39
, pp.
1281
1291
.
5.
Fabre, J., Ferschneider, G., and Masbernat, L., 1983, “Intermittent Gas Liquid Flow in Horizontal or Weakly Inclided Pipes,” Proc. Int. Conf. on Physical Modelling of Multiphase Flow, Coventry, U.K.
6.
Mandhane
,
J. M.
,
Gregory
,
G. A.
, and
Aziz
,
K.
,
1974
, “
A Flow Pattern Map for Gas-Liquid Flows in Horizontal Pipes
,”
Int. J. Multiphase Flow
,
1
, pp.
537
553
.
7.
Barnea
,
D. A.
,
1987
, “
A Unified Model for Predicting Flow-Pattern Transitions for the Whole Range of Pipe Inclinations
,”
Int. J. Multiphase Flow
,
13
, pp.
1
12
.
8.
Lin
,
P.
, and
Hanratty
,
T. J.
,
1987
, “
The Effect of the Pipe Diameter on the Flow Patterns for Air-Water Flow in Horizontal Pipes
,”
Int. J. Multiphase Flow
,
13
, pp.
549
563
.
9.
Ruder
,
Z.
, and
Hanratty
,
T. J.
,
1990
, “
A Definition of Gas-Liquid Plug Flow in Horizontal Pipes
,”
Int. J. Multiphase Flow
,
16
, pp.
233
242
.
10.
Andreussi, P., and Paglianti, A., “The Boundary of Slug Flow in Near Horizontal Pipes,” 1995, Proc. Int. Conf. on Multiphase Flow in Industrial Plants, Amalfi, Italy.
11.
Guglielmini G., and Soressi, E., 1996, “Experimental Data of Two-Phase Pressure Drop Across Sudden Area Contractions in Horizontal Flow,” Proc. 5th Int. Conf. Multiphase Flow in Industrial Plants, Amalfi, Italy.
12.
Fossa
,
M.
,
1998
, “
Design and Performance of a Conductance Probe for Measuring the Liquid Fraction in Two-Phase Gas-Liquid Flows
,”
J. Flow Meas. Instrum.
,
9
, pp.
103
109
.
13.
Asali
,
J. C.
,
Hanratty
,
T. J.
, and
Andreussi
,
P.
,
1985
, “
Interfacial Drag and Film Height for Vertical Annular Flow
,”
AIChE J.
,
31
, pp.
895
902
.
14.
Andreussi
,
P.
,
Di Donfrancesco
,
A.
, and
Messia
,
M.
,
1988
, “
An Impedance Method for the Measurement of Liquid Hold-Up in Two Phase Flow
,”
Int. J. Multiphase Flow
,
14
, pp.
777
785
.
15.
Tsochatzidis
,
N. A.
,
Karapantios
,
T. D.
,
Kostoglou
,
M. V.
, and
Karabelas
,
A. J.
,
1992
, “
A Conductance Method for Measuring Liquid Fraction in Pipes and Packed Beds
,”
Int. J. Multiphase Flow
,
5
, pp.
653
667
.
16.
Costigan
,
G.
, and
Whalley
,
P. B.
,
1997
, “
Slug Flow Regime Identification from Dynamic Void Fraction Measurement in Vertical Air-Water Flows
,”
Int. J. Multiphase Flow
,
23
, pp.
263
282
.
17.
Arosio, S., Bertola, V., and Fossa, M., 1999, “Comparative Analysis of Intermittent Air-Water Flow Structure by Means of Different Measurement Techniques,” Proc. 2nd Int. Symp. Two-Phase Flow Modelling and Experimentation, Pisa, Italy.
18.
Jones
,
O. C.
, and
Zuber
,
N.
,
1975
, “
The Interrelation between Void Fraction Fluctuations and Flow Patterns in Two-Phase Flow
,”
Int. J. Multiphase Flow
,
2
, pp.
273
306
.
19.
Press, W. H., Teukolsky, S. A., Vetterling W. T., and Flannery, B. P., 1994, Numerical Recipes in Fortran, Cambridge Univ. Press, pp. 545–550.
20.
Nydal
,
O. J.
,
Pintus
,
S.
, and
Andreussi
,
P.
,
1992
, “
Statistical Characterization of Slug Flow in Horizontal Pipes
,”
Int. J. Multiphase Flow
,
3
, pp.
439
453
.
21.
Nicklin
,
D. J.
,
Wilkes
,
J. O.
, and
Davidson
,
J. F.
,
1962
, “
Two-Phase Flow in Vertical Tubes
,”
Trans. Inst. Chem. Eng.
,
40
, pp.
61
68
.
22.
Bendiksen
,
K. H.
,
1984
, “
An Experimental Investigation of the Motion of Long Bubbles in Inclined Tubes
,”
Int. J. Multiphase Flow
,
6
, pp.
467
483
.
23.
Woods
,
B. D.
, and
Hanratty
,
T. J.
,
1996
, “
Relation of Slug Stability to Shedding Rate
,”
Int. J. Multiphase Flow
,
22
, pp.
809
828
.
24.
Benjamin
,
T. B.
,
1968
, “
Gravity Current and Related Phenomena
,”
J. Fluid Mech.
,
31
, pp.
209
248
.
25.
Armand, A. A., and Treshchev, G., 1959, “Investigation of the Resistance during the Movement of Steam-Water Mixtures in Heated Pipe at High Pressure,” AERE Lib/Trans, Vol. 81.
26.
Lin
,
P. Y.
, and
Hanratty
,
T. J.
,
1986
, “
Prediction of the Initiation of Slugs with Linear Stability Theory
,”
Int. J. Multiphase Flow
,
12
, pp.
79
98
.
27.
Tronconi
,
E.
,
1990
, “
Prediction of Slug Frequency in Horizontal Two-Phase Slug Flow
,”
AIChE J.
,
36
, pp.
701
709
.
28.
Taitel
,
Y.
, and
Dukler
,
A.
,
1976
, “
A Theoretical Approach to the Lochart-Martinelli Correlation for Stratified Flow
,”
Int. J. Multiphase Flow
,
2
, pp.
591
605
.
29.
Gregory
,
G. A.
, and
Scott
,
D. S.
,
1972
, “
Correlation of Liquid Slug Velocity and Frequency in Cocurrent Horizontal Gas-Liquid Slug Flow
,”
Ind. Eng. Chem. Proc. Des. Dev.
,
11
, pp.
317
318
.
You do not currently have access to this content.