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.

Void fraction measurements in partial cavitation regimes by X-ray computed tomography

“…The difference between the path lengths measured at the maximum angle and parallel to the detector is 0.1% of the parallel beam path. Therefore, the cavitation cloud is assumed to be projected to the detector by parallel X-ray beams ( Wang et al, 2018 ). This assumption is also validated by comparing the reconstructed geometry against the nominal geometry, as shown in Fig.…”

Validation and uncertainty quantification of multiphase-CFD solvers: A data-driven Bayesian framework supported by high-resolution experiments

“…The schematic of the experimental test loop is depicted in flow parameters such as void fraction, velocity, and superficial gas velocity [13,42].…”

“…For liquid-phase measurement, the integration of Particle Image Velocimetry (PIV) and Planar Laser-Induced Fluorescence (PLIF) techniques [11,12], associated with the methods to minimize the effect of light distortion on bubble surfaces have been developed to measure liquid-phase velocity field in bubbly flow. These two techniques, along with the conductivity probe, a mature and robust technique for measuring local gas phase QoIs [13], could be integrated to develop a comprehensive database for the UQ of MCFD simulations.…”

An efficient algorithm for overlapping bubbles segmentation

“…Currently, numerous techniques can be used to measure bubbly flow that can be classified into two main groups, namely: intrusive and non-intrusive techniques. Typical intrusive techniques include conductivity probe [1,2] and phase sensitive constant temperature anemometry [3]. Non-intrusive techniques include laser doppler anemometry [4], X-ray and ɣ-ray computed tomography [5,6] and image processing techniques [7,8].…”