Investigation into the Statistical Characteristics of Bubbles in Two-Phase Flow : 1st Report. Fundamentals of the Instrumentation Using the Electric Resistivity Probe Technique

抄録

The purpose of this paper is to establish an electric resistivity method which enables estimation of the local void fraction and the local bubble size distribution in two-phase flow. The probe consists of a thin platinum wire with a finely sharpened edge as a point electrode. It is made clear that the probe signal changes are not stepwise corresponding to the phase changes from gas to liquid or vice versa, and that these can be fitted by the first order lag curves for both rising and falling duration. In order to analyse such probe signals a digital counter with a special trigger circuit functioning by a pulse width and voltage level comparator was employed. The fundamental equations are derived expressing the relations between the local bubble size distribution and the measured frequency of bubbles, and between the local void fraction and the measured dwell time of bubbles.