Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.
This paper reports the results of an experimental study concerned with the phase distributions of gas-liquid multiphase flows experienced in a vertical riser. Scale experiments were carried out using a mixture of air and silicone oil in 6 m long riser pipe with an internal diameter pipe of 67 mm. A series of pipe flow experiments were performed for a range of injected superficial air velocities over the range 0.047 to 2.836 m/ s, whilst maintaining the liquid superficial velocity of 0.047 m/ s. Measurements of radial time averaged void fractions across a pipe section located 5.15 m from the pipe flow injection were obtained using a capacitance wire mesh sensor (WMS). The data were recorded at a frequency of 1000 Hz over an interval of 60 seconds. A comparison of the experimental data was performed against a published equation presented in  and used by  to investigate the flow structure of air - water mixtures in a bubble column:
It was concluded that the model was able to satisfactorily replicate the observed radial void fraction profile (mean relative error is within 5.7 %) at the higher gas superficial velocities . It was found that the 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. Reasonably symmetric radial void fraction profiles were obtained when the air-silicone oil was fully developed, and the shape of the symmetry profile was strongly dependent on superficial gas velocity.