The coupled Eulerian-Lagrangian approach was used to study the effects of bubble size and high-pressure transport behaviour on the phase distribution mechanisms in vertically upward air-water two-phase bubbly flows. The approach solves the conservation equations of liquid phase in Eulerian space and equations of motion in conjunction with the random walk method for dispersed air bubbles in Lagrangian space. Numerical calculations were performed under conditions of three bubble diameters (2.8, 4.0 and 5.0 mm) and two different pressure levels (0.1 and 7.17 MPa) to explore the flow and void fraction development phenomena. Simulation results indicate the tendency of higher slip ratios and the movement of the void fraction peak towards the flow core for larger gas bubbles. In the pressure range 0.1-7.17 MPa, predictions reveal that the effect of high-pressure transport behaviour on the phase distribution is insignificant.
BankoffS. G.A variable density single-fluid model for two-phase flow with particular reference to steam-water flow, pt.2. J. Heat Transfer, 1960, 82, 265–271.
2.
LevyS.Prediction of two-phase pressure drop and density distribution phenomena mixing length theory, pt.2. J. Heat Transfer, 1963, 85, 137–152.
3.
BeatieD. R. H.Two-phase flow structure and mixing length theory. Nucl. Engng and Des., 1972, 21, 46–64.
4.
DelhayeJ. M.General equations of two-phase systems and their applications to air-water bubble flow and to steam-water flashing flow. In 11th Heat Transfer Conference, Minneapolis, 1969, ASME paper 69-HT-63.
5.
BeyerleinS. W.CossmannR. K.RichterH. J.Prediction of bubble concentration profiles in vertical turbulent two-phase flow. Int. J. Multiphase Flow, 1985, 11, 629–641.
6.
LiuT. J.Experimental investigation of turbulence structure in two-phase bubbly flow. PhD thesis, Northwestern University, 1989.
7.
de BertodanoLopez M.LaheyR. T.Jr.JonesD. C.Development of a k-∊ model for bubbly two-phase flow. Trans. ASME, 1994, 116, 128–134.
8.
LaheyR. T.The analysis of phase separation and phase distribution phenomena using two-fluid models. Nucl. Engng and Des., 1990, 122, 17–40.
9.
SerizawaA.KataokaI.MichiyoshiI.Turbulence structure of air-water bubbly flow. Int. J. Multiphase Flow, 1975, 2, 221–259.
10.
DrewD.LaheyR. T.Phase distribution mechanisms in turbulent two-phase flow in a circular pipe. J. Fluid Mechanics, 1982, 117, 91–106.
11.
PokharnaH.MoriM.RansomV. H.The particle fluid model and using Lagrangian representation in two-phase flow modeling. Nucl. Engng and Des., 1997, 175, 59–69.
12.
MonjiH.MatusiG.Effect of bubble size on structure of vertical bubble flow. In Proceedings of International Conference on Multiphase Flows, Tsukuba, Japan, 24–27 September 1991, pp. 449–452.
13.
MatusiG.Characteristic structure of upward bubble flow. In Dynamics of Two-Phase Flows, 1992, pp. 359–377 (CRC Press).
14.
SerizawaA.MichiyoshiI.KataokaI.ZunI.Bubble size effect on phase distribution. In Dynamics of Two-Phase Flows, 1992, pp. 379–400 (CRC Press).
15.
LiuT. J.Bubble size and entrance length on void development in a vertical channel. Int. J. Multiphase Flow, 1993, 19, 99–113.
16.
KuoT. C.YangA. S.PanC.ChiengC. C.Eulerian-Lagrangian computations on phase distribution of two phase bubbly flow. Int. J. Numer. Meth. Fluid, 1997, 24, 1–15.
17.
SatoY.SadatomiM.SekoguchiK.Momentum and heat transfer in two-phase bubble flow. Int. J. Multiphase Flow, 1981, 7, 167–177.
18.
MartinuzziR.PollardA.Comparative study of turbulence models in predicting turbulent pipe flow. Am. Inst. Aeronaut. Astronaut. J., 1989, 27, 29–36.
19.
LaunderB. E.SpaldingD. B.The numerical computation of turbulent flows. Computer Meth. in Appl. Mech. Engng, 1974, 269–289.
20.
ZumwaltL. C.KallioG.A numerical simulation of thermophoretic deposition in turbulent flow. ASME-FED-91, 1991, pp. 1–9.
21.
KuoT. C.YangA. S.PanC.ChiengC. C.Prediction of the entrance region effect on turbulent bubbly flow in pipes. In Proceedings of 8th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Kyoto, 30 September-4 October 1997, Vol. 1, pp. 93–100.
22.
Van DoormaalJ. V.RaithbyG. D.Enhancements of the SIMPLE method for predicting incompressible fluid flows. Numer. Heat Transfer, 1984, 7, 147–163.
23.
KuoT. C.YangA. S.PanC.ChiengC. C.Effects of two phase turbulent structure interactions on phase distribution in bubbly pipe flows. Jap. Soc. Mech. Engrs, Ser. B, 1999, 42(3), 419–428.
24.
KuoT. C.YangA. S.PanC.ChiengC. C.Numerical formulation on two-phase turbulence using Eulerian-Lagrangian approach. 2nd International Symposium on Turbulence, Heat and Mass Transfer, 1997, pp. 817–822 (Delft University Press).
25.
Van WylenG. J.SonntagR. E.Fundamentals of Classical Thermodynamics, 3rd edition, 1985, Appendix (John Wiley, Singapore).
26.
GlasstoneS.SesonskeA.Nuclear Reactor Engineering, 1980, p. 787 (Van Nostrand Reinhold, New York).
