Development of Methodology for Measuring Liquid Film Thickness Based on Three-ring Conductance Method

In this study, three-ring method and parallel circuitry system were coupled to measure the liquid film thickness. And the parallel circuitry system was devised for effective signal processing of three-ring method. In addition, with applying the FPCB sensor on liquid film flow experiment, the flow pattern of downward film flow was observed. The temperature compensation range was limited to 10 .deg. in case of using current ratio. Liquid film thickness is an important factor for understanding the two-phase annular / film flow. Generally, measuring the liquid film thickness with high time and spatial resolution has been limited in two-phase flow experiments. Recently, measurement of the local liquid film thickness with high time and spatial resolution have achieved by combining electrical conductance method with wire-mesh circuitry. Though this methodology has high resolutions, the applicability is limited in applying dynamic temperature conditions which involve heat transfer since the electric conductivity of the liquid is affected by its temperature. Electrical conductivity of the water generally increases about 2% when the water temperature increases 1 .deg. . Therefore, experiments applying electrical methods have limited to isothermal flow condition despite the fact that most two phase flows involve heat transfer. The objective of this study is developing a measurement methodology for measuring local liquid film thickness in varying temperature condition. In order to improve the temperature varying range, additional impedance analysis and tests for various electrode design are required. Besides coupling this methodology with wiremesh system is necessary to obtain high time resolution to measure the film thickness instantaneously.