Bubble size effect on low liquid input drift–flux parameters

We investigated the effect of bubble size on the drift–flux parameters at low liquid flow conditions by measuring the radial profiles of void fraction and phase velocities in a vertical bubbly pipe flow of diameter and height . To study the effect of the bubble size we used two different types of bubble inlets. We measured the local bubble fraction and velocity Ug by using single and four-point-optical fibre probes, and we used Laser Doppler Anemometry to determine the liquid velocity Ul. The distribution parameter C0 and the weighted mean drift velocity |Udrift| were directly computed from the local measurements at a height on our experimental set-up. Both parameters were influenced by the bubble size. Provided no liquid flow reversal occurred at the near wall region, the distribution parameter reached a below unity minimum plateau value of C0=0.95 for wall peaking void fraction profiles. At low liquid input conditions both the liquid input and bubble size had an influence on the distribution parameter. Extreme values such as C0>2 were measured. From these measurements we developed models for the drift–flux parameters to take into account the effect of bubble size and input-flow conditions for our intermediate pipe diameter value. These models were tested and validated with separately collected experimental data.

[1]  Isao Kataoka,et al.  Turbulence structure of air-water bubbly flow—II. local properties , 1975 .

[2]  N. Zuber,et al.  Average volumetric concentration in two-phase flow systems , 1965 .

[3]  R. F. Mudde,et al.  Liquid velocity field in a bubble column: LDA experiments , 1997 .

[4]  Robert F. Mudde,et al.  Bubble Velocity and Size Measurement with a Four‐Point Optical Fiber Probe , 2003 .

[5]  A. K. Agrawal,et al.  Shape of liquid drops moving in liquid media , 1966 .

[6]  M. Ishii,et al.  Flow regime transition criteria for upward two-phase flow in vertical tubes , 1984 .

[7]  Hidesada Tamai,et al.  Transverse migration of single bubbles in simple shear flows , 2002 .

[8]  Barry J. Azzopardi,et al.  Effects of initial bubble size on flow pattern transition in a 28.9 mm diameter column , 2002 .

[9]  R. Clift,et al.  Bubbles, Drops, and Particles , 1978 .

[10]  H H Bruun,et al.  A computer-based hot-film technique for two-phase flow measurements , 1995 .

[11]  T. J. Liu.  Bubble size and entrance length effects on void development in a vertical channel , 1993 .

[12]  Robert F. Mudde,et al.  Hydrodynamical similarities between bubble column and bubbly pipe flow , 2001, Journal of Fluid Mechanics.

[13]  Gretar Tryggvason,et al.  Dynamics of homogeneous bubbly flows Part 1. Rise velocity and microstructure of the bubbles , 2002, Journal of Fluid Mechanics.

[14]  R. F. Mudde,et al.  Application of LDA to bubbly flows , 1998 .

[15]  H. Kubota,et al.  BUBBLES GENERATED FROM POROUS PLATE , 1968 .

[16]  Mamoru Ishii,et al.  One-dimensional drift–flux model for two-phase flow in a large diameter pipe , 2003 .

[17]  Roberto Zenit,et al.  Measurements of the average properties of a suspension of bubbles rising in a vertical channel , 2001, Journal of Fluid Mechanics.

[18]  J. Fabre,et al.  Gas-Liquid Slug Flow , 1994 .

[19]  R. V. A. Oliemans,et al.  Influence of bubble size on the transition from low-Re bubbly flow to slug flow in a vertical pipe , 2002 .

[20]  Yasuhiko Tanaka,et al.  ELUTRIATION OF FINES FROM FLUIDIZED BED , 1972 .

[22]  J. Marié,et al.  Measurement of local flow characteristics in buoyancy-driven bubbly flow at high void fraction , 2002 .

[23]  M. Ishii,et al.  Distribution parameter and drift velocity of drift-flux model in bubbly flow , 2002 .

[24]  S. Van Geest.  Comparison of different air injection methods to improve gas-lift performance , 2000 .

[25]  A. E. Dukler,et al.  Modelling flow pattern transitions for steady upward gas‐liquid flow in vertical tubes , 1980 .

[26]  J. M. Burgess,et al.  The measurement of bubble parameters in two-phase dispersions—I: The development of an improved probe technique , 1975 .

[27]  Robert F. Mudde,et al.  Performance of 4-tip Optical Fiber Probe and Bubble Characterizations by the Probe in Turbulent Bubbly Flows , 2001 .

[28]  R. F. Mudde,et al.  On the application of LDA to bubbly flow in the wobbling regime , 1999 .

[29]  John F. Davidson,et al.  The motion of a large gas bubble rising through liquid flowing in a tube , 1978, Journal of Fluid Mechanics.

[30]  J. Marié,et al.  An upward turbulent bubbly boundary layer along a vertical flat plate , 1995 .

[31]  J. J. Frijlink.  Physical aspects of gassed suspension reactors , 1987 .

[32]  Eckhard Krepper,et al.  Prediction of radial gas profiles in vertical pipe flow on the basis of bubble size distribution , 2001 .