Integration of conductivity probe with optical and x-ray imaging systems for local air-water two-phase flow measurement

Abstract

Various techniques have been developed in the past to measure the different parameters in two-phase flow. Among them, the multi-sensor conductivity probe is one of the most commonly used techniques because of its good overall performance. Recently, more advanced techniques, such as high-speed optical imaging and fast x-ray densitometry, have matured and become easily accessible. The main objective of this work is to compare and integrate these different techniques, to achieve a more accurate and complete measurement of two-phase flow. In this study, a double-sensor conductivity probe is used to measure the local time-averaged parameters along the radial direction of a 2.54 cm ID round pipe. An x-ray densitometry system is used to measure the chordal averaged void fraction and gas velocity. A high-speed camera system is employed to provide a visualization of the two-phase flow structure and obtain the line-averaged gas velocity. The unique advantages and main uncertainties of these three techniques are analyzed by considering their measuring principles and possible issues in practical measurements. From this, a method is developed to integrate the data obtained by the optical and x-ray systems into the probe signal processing. Better accuracy can be achieved using this method for various local two-phase flow parameters, including the void fraction, bubble velocity and superficial gas velocity, compared to the original probe measurements.