Measurement of Interfacial Structure on Liquid Film in Annular Flow Using Laser Focus Displacement Meter (2nd Report, Disturbance Wave Frequency and Local Minimum Film Thickness)

Abstract

In this study, a precise database of microscopic interfacil wave-structure was obtained for annular two-phase flow developing in a vertical pipe. Using a laser focus displacement meter (LFD), measurements of such local properties as the minimum film thickness and passing frequency of the waves along the pipe were conducted. The results showed that the passing frequency of disturbance waves decreased gradually with some oscillations in the pipe axial direction, whose phenomena had a similarity with those of maximum film thickness reported in the 1st report. These unique phenomena were also discussed from a view of pressure resonant interactions based on the experimental results of pressure propagation in the pipe. Minimum thickness of the film decreased with flow development and with increasing gas flow rate. These results were discussed taking into account the buffer layer calculated from Karman's three-layer model. Correlation was proposed for obtained minimum film thickness in regarding to interfacial shear stress and the Reynolds number of the liquid. This correlation expressed the minimum film thickness obtained from the experiment withis 5% deviation.