抄録
Void fraction is one of important physical values for gas-liquid two-phase flow, and it is an essential parameter for designs and performance evaluations of devices, including a core of light-water nuclear reactors and so on. In the present study, constant electrical current method was applied to bubbly flows for electrical void fraction measurements which can realize on-line measurement. Constant electrical current method in previous studies has been applied in a liquid film and an annular flow. Void fraction is estimated from cross-section ratio of gas and liquid phases in this method. For this reason, dispersed bubbly flow is not applied since the cross-section ratio is not constant in flow direction. In this study, Maxwell's theory and polarization method are applied to calculate void fractions from voltages measured with constant electrical current method. Voltages are measured through four terminals sensing method with ring electrodes and a constant current power supply in this experiment. Working fluid is air and tap water. In order to compare with void fractions calculated from cross-section ratio, Maxwell's theory and polarization method, void fractions are measured through quick valve method. And a high-speed camera and a metal halide lamp are used to observe flow pattern. In this experiment, void fraction in bubbly flow can be measured accurately with polarization method. As this result, it is suggested that polarization method is more effective than cross-section ratio method and Maxwell's theory in bubbly flow.
