The obtained database contains the radial profiles of both gas- and liquid-phase parameters at three axial locations along the test section. Seven air-water two-phase flow conditions spanning the bubbly, slug, churn-turbulent, and annular flow regimes are measured in this facility. These local measurement techniques are first used in a 25.4 mm circular pipe test section. By combining these techniques, the local void fraction, bubble velocity, interfacial area concentration, bubble frequency, liquid velocity, turbulence intensity, etc., in various two-phase flow regimes can be obtained. In this project, four advanced local measurement systems, including Particle Image Velocimetry and Planar Laser-Induced Fluorescence (PIV-PLIF), high-speed imaging, x-ray more » densitometry, and multi-sensor conductivity probe are employed to measure the local two-phase flow parameters of both gas and liquid phases. The main objective of this work is to develop a comprehensive database of two-phase flows that can be used to validate two-phase CFD codes such as NEK-2P. However, two-phase flow models and associated closure relations are not well established for CFD applications, which is partly due to the lack of high-quality validation data. Three-dimensional (3-D) two-phase Computational Fluid Dynamics (CFD) codes are emerging as a powerful and potentially practical tool for applications in which detailed local flow information is needed. Finally, a better accuracy could be achieved using this method for various more » local two-phase flow parameters including void fraction, bubble velocity and superficial gas velocity, compared to the original probe measurements. From this, a method is developed to integrate the data obtained by the optical and X-ray systems into the probe signal processing. The unique advantages and main uncertainties of these three techniques are analyzed by considering their measuring principles and possible issues in practical measurements. A high speed camera system is employed to provide the visualization of the two-phase flow structure and obtain the line-averaged gas velocity.
An X-ray densitometry system is used to measure the chordal averaged void fraction and gas velocity. 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. 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. Recently, more advanced techniques such as high speed optical imaging and fast X-ray densitometry become mature and easily accessible. Among them, the multi-sensor conductivity probe is one of the most commonly used techniques because of its good overall performance. Various techniques have been developed in the past to measure different parameters in two-phase flow.