Measurement of circumferential and axial liquid film velocities in horizontal annular flow

Abstract

The mechanism of liquid transport around the inner perimeter of a tube in horizontal annular flow has been experimentally investigated by using a photochromic dye activation technique. The liquid film velocities in circumferential and axial directions were measured by forming a drak spot of dye trace in the liquid film in a non-intrusive manner and recording the subsequent motion of the spot trace with a high-speed video camera. The experiments were conducted in a 5.28 m long horizontal tube with 25.4 mm i.d. at near atmospheric pressure conditions using air and kerosene. Over the ranges of gas and liquid flow rate tested (16 < J G < 40 m/s and 0.04 < J L < 0.1 m/s), the base film was always seen to drain down the tube wall. During the periodic passage of disturbance waves, however, the spot dye trace moved upward indicating the transport of liquid in an upward direction against the force of gravity. The ripples propagating upward over the base film were also observed to transport the liquid upward, however, their contributions were less significant compared to those of the disturbance waves. These results indicate that the liquid is transported to the upper part of the tube by the disturbance waves and not by the secondary gas flow or other mechanisms as previously hypothesized.