The thermohydraulic modeling of two phase flow is very important for nuclear reactor operation and safety analyses. For the thermohydraulic modeling of two phase flow, the information of several parameters determined by experiment such as void fraction, liquid film thickness and flow regimes are required.
This study is concerned with the liquid film thickness measurement and flow regime characterization using the ultrasonic pulse-echo method to eliminate the disadvantage of existing techniques.
Measurements of liquid film thickness on the plate and in the tube are performed, and the effects of wall thickness, wallmaterial and ultrasonic frequency on the measurement of liquid film thickness are also investigated. In addition, the measurement of liquid film thickness using stand-off rod is also investigated. On the other hand, for the characterization of flow regime, single phase flow, bubbly flow, slug flow and stratified flow are formed in a horizontal and vertical tube and the ultrasonic echo waveforms corresponding to these various flow patterns are measured.
Comparison of the real film thickness with the experimental results show a good agreement within ± 1% error. And it is found that the ultrasonic echo waveforms corresponding to the various flow patterns can clearly be classified.