PROPERTIES OF THE LIQUID LAYER IN HORIZONTAL ANNULAR-FLOW

Time records have been collected of local liquid film thickness, using parallel-wire conductance probes, in a new 50.8 mm i.d. pipe loop. Statistical analysis of these records allows the study of the circumferential variation of time-averaged thickness, of RMS values and of other quantities. The power spectra show that the dominant frequency associated with large disturbance waves is < 10 Hz at low gas velocities, displaying a tendency to increase with gas flow rate. By combining signal cross-correlation data with visual observations, it is shown that the disturbance waves tend to deform rapidly, move on a plane inclined with respect to the vertical and cover an increasingly larger portion of the circumference with increasing gas velocity. The mean large wave height at the pipe bottom is linearly related to the local RMS value. It is also a strong function of gas flow rate, with a moderate dependence on liquid flow rate. The wave steepness shows a similarly strong dependence on gas flow rate. However, the disturbance wave intermittency appears to be almost independent of gas as well as liquid flow rates.