Experimental Investigation of Phase Distributions of Two-phase Air-silicone Oil Flow in a Vertical Pipe

This paper reports the results of an experimental study conducted to characterise the gas-liquid multiphase flows experienced within a vertical riser transporting a range of gas-liquid flow rates. The scale experiments were performed using an air/silicone oil mixture within a 6 m long riser. The superficial air velocities studied ranged from 0.047 to 2.836 m/ s, whilst maintaining a liquid superficial velocity at 0.047 m/ s. Measurements of the mean cross-sectional and time average radial void fraction were obtained using a wire mesh sensor (WMS). The data were recorded at an acquisition frequency of 1000 Hz over an interval of 60 seconds. For the range of flow conditions studied, the average void fraction was observed to vary between 0.1 and 0.9. An analysis of the data collected concluded that the observed void fraction was strongly affected by the superficial gas velocity, whereby the higher the superficial gas velocity, the higher was the observed average void fraction. The average void fraction distributions observed were in good agreement with the results obtained by other researchers. When the air-silicone oil flows were fully developed reasonably symmetric profiles were observed, with the shape of the symmetry profile being strongly dependent on the superficial gas velocity.

Authors:

• M. Abdulkadir
• V. Hernandez-Perez
• S. Sharaf
• I. S. Lowndes
• B. J. Azzopardi

Keywords:

• WMS
• phase distribution
• silicone-oil
• riser

References:

[1] Abdulkadir, M., Zhao, D., Sharaf, S., Abdulkareem, L.S., Lowndes, I.S.,
Azzopardi, B.J., 2010, Interrogating the effect of bends on gas-liquid
flow using advanced instrumentation, ICMF 2010, 7th International
Conference on Multiphase Flow, Tampa, FL, USA. (Accepted)
[2] Gardner, G. C., and Neller, P. H., 1969, Phase distributions flow of an
air-water mixture round bends and past obstructions, Proc. Inst. Mech.
Engr., Vol. 184, No. 3C, pp. 93 -101
[3] Ohnuki, A. and Akimoto, H. (1996), An experimental study on
developing air -water two-phase flow along a large vertical pipe: Effect
of air injection method, Int. J. Multiphase Flow, Vol. 22, No. 6, pp.
1143-1154.
[4] Ohnuki, A. and Akimoto, H. (2000), Experimental study on transition of
flow pattern and phase distribution in upward air-water two-phase flow
along a large vertical pipe, Int. J. Multiphase Flow, Vol. 26, No. 3, pp.
367-386.
[5] Shen, X., Mishima, K., and Nakamura, H. (2004), Two-phase
distribution in a vertical large diameter pipe, Int. J. Heat and Mass
Transfer, Vol. 48, pp. 211-225
[6] Azzopardi, B. J., Hernandez Perez, V., Kaji, R., Da Silva, M. J., Beyer,
M., and Hampel, U., 2008, Wire mesh sensor studies in a vertical pipe,
HEAT 2008, Fifth International Conference on Multiphase Systems,
Bialystok, Poland.
[7] Azzopardi, B. J., 1997, Drops in annular two-phase flow, International
Journal of Multiphase Flow, Vol. 23, pp. 1-53.
[8] Geraci, G., Azzopardi, B. J., and Van Maanen, H.R.E., 2007a,
Inclination effects on circumferential film distribution in annular gas/
liquid flows, AIChE Journal, Vol. 53, No.5, pp. 1144-1150.
[9] Geraci, G., Azzopardi, B. J., and Van Maanen, H.R.E., 2007b, Effects of
inclination on circumferential film thickness variation in annular gas/
liquid flows, Chemical Engineering Science, Vol. 62, No.11, pp. 3032-
3042.
[10] Hernandez-Perez, V., 2007, Gas-liquid two-phase flow in inclined pipes,
a PhD Thesis, University of Nottingham, United Kingdom
[11] Prasser, H.M., Krepper, E. and Lucas, D., Evolution of the two-phase
flow in a vertical tubeÔÇödecomposition of gas fraction profiles according
to bubble size classes using wire-mesh sensors, Int. J. Therm. Sci. 41
(2002) 17-28
[12] Carver, M. B., 1984, Numerical computation of phase separation in two
fluid flow, ASME Paper No. 82-FE-2, Vol. 106/ 153
[13] Carver, M.B., and Salcudean, M., 1986, Three-dimensional numerical
modelling of phase distribution of two - fluid flow in elbows and return
bends, Numerical Heat Transfer, Vol. 10, pp. 229-251
[14] Costigan, G., and Whalley, P. B., 1996, Slug flow regime identification
from dynamic void fraction measurements in vertical air-water flows.
Int. J. Multiphase Flow, Vol. 23, No. 2, pp. 263-282