An experimental study on local interfacial parameters in a horizontal bubbly two-phase flow

Abstract

The internal phase distribution of cocurrent, air-water bubbly flow in a 50.3 mm dia transparent pipeline has been experimentally investigated by using a double-sensor resistivity probe. Liquid and gas volumetric superficial velocities ranged from 3.74 to 5.71 and 0.25 to 1.37 m/s, respectively, and average void fractions ranged from 4.30 to 22.5%. The local values of void fractions, interfacial area concentration, mean bubble diameter and bubble interface velocity, chord-length and frequency distributions were measured. The experimental results indicate that the void fraction, interfacial area concentration and bubble frequency have local maxima near the upper pipe wall, and the profiles tend to flatten with increasing void fraction. The observed peak void fraction can reach 0.65, the peak interfacial area can go to 900–1000 m 2/m 3, and the bubble frequency can reach a value of 2200/s. These ranges of values have never been reported for vertical bubbly flows. It is found that either decreasing the liquid flow rate or increasing the gas flow would increase the local void fraction, the interfacial area concentration and the bubble frequency. The axial bubble interface velocity and the Sauter mean diameter profiles show a relatively uniform distribution except near the upper pipe wall, where a sharp reduction in the velocity and mean diameter occurs. The local bubble velocity and the mean diameter generally increase with the gas flow rate.