Experimental Characterization of Cylindrical Bubble Column Flow

1 Experimental Characterization of Cylindrical Bubble Column Flow 

The literature reporting measurements of gas and liquid velocities, flow patterns, and phase distribution of two-phase flow in pipes or cylindrical columns is extensive. Introductorily, a few essential observations are summarized. 

Several thorough reviews on the characteristics of vertical bubbly flows have been reported [59, 62, 66, 104]. Bubble columns are usually operated at very low or zero liquid fluxes, and larger gas fluxes. Experimental investigations performed by several groups show that under these flow conditions, core peaking is the rule. 

In a pioneering investigation, Serizawa [127, 128] measured the lateral void distribution as well as the turbulent axial liquid velocity fluctuations for bubbly air/water up-flows in a vertical pipe of diameter 60 (mm) inner diameter. They used electrical resistivity probes to measure the local void fraction, the bubble impaction rate, the bubble velocity and its spectrum. Turbulence quantities, such as the liquid phase mean velocity, and the axial turbulent fluctuations were measured using a hotfilm anemometer. A supplementary 

Hills [57] studied the radial variation of gas holdup and liquid velocity in a bubble column with diameter 138 (mm). The gas holdup was measured with a conductivity probe, while the liquid velocity was measured using a modified Pitot tube. He used three different gas distributors. The superflcial 

Menzel et al. [108] found core peaking for all the gas fluxes they studied in their investigation, and the time averaged radially varying velocity component profiles have a maximum at the core of the column as shown in Fig. 8.4. The column used had a diameter of 0.6 m, and a height of 5.44 m. The system considered was air-water. 

The water was operated in batch mode. The velocity measurements were performed with a hot-film anemometer. 

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