Experimental investigations of the circumferential liquid film distribution of air-water annular two-phase flow in a horizontal pipe

The circumferential film thickness distribution in an air-water horizontal annular two-phase flow was investigated in 26 mm pipe diameter by using the conductance probe. The superficial gas and liquid velocities were 10-40 m/s and 0.025-0.4 m/s, respectively. In general, the film thickness decreases as the liquid velocity decreases and the gas velocity increases. For low superficial gas velocity, high asymmetry of liquid film thickness distribution is generally found. In addition, the liquid film at the upper half of the pipe mostly consists of surge of waves with frequency lower than that of the bottom. At the lowest superficial liquid velocity of the present experimental range, the mean film thickness at the bottom ranges from 0.24 mm to 1.3 mm. Meanwhile, at the highest superficial liquid velocity, it ranges from 1.0 to 4.29 mm, depending on the superficial gas velocity. At the higher superficial gas velocity, a more uniform of liquid film thickness distribution is commonly found. Under this flow condition, the wave at the upper has a similar frequency to that of the lower half and a coherent liquid wave is normally found. To predict the film thickness at any circumferential position, an empirical correlation is proposed on the basis of the physics of the phenomena. In comparison to the available experimental data, the correlation has a good capability to predict the circumferential liquid film thickness distribution. (C) 2017 Elsevier Inc. All rights reserved.