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Title Measurement and Modeling of the Liquid-phase Turbulence in Adiabatic Air-water Two-phase Flows with a Wide Range of Void Fractions
Publication Date
Degree PhD
Discipline/Department Mechanical Engineering
Degree Level doctoral
University/Publisher The Ohio State University
Abstract The current work focuses on the measurement and modeling of liquid-phase turbulence in adiabatic air-water two-phase flow with a relatively wide range of void fractions. The purpose of this research work is to understand and accurately predict two-phase flow behavior. Emphasis is placed on the liquid-phase turbulence characteristics for different flow regimes. A state-of-the-art particle image velocimetry (PIV) was used to perform liquid-phase turbulence measurements on two flow channels, a circular pipe with an inner diameter (ID) of 50 mm at OSU and a rectangular channel with a cross section dimension of 30 mm x 10 mm at Virginia Tech, respectively. Three local measurement ports were used to study the flow development along the test section. An advanced optical phase separation method, namely planar laser-induced fluorescence (PLIF), was applied to separate the liquid-phase particles from bubbles in the flow. An image pre-processing scheme was developed and imposed on the two-phase flow PIV images to remove remaining noise and therefore improve phase separation. The combination of the optical phase separation method and image pre-processing scheme proved capable of effectively reducing the noise in the two-phase flow PIV images and therefore increasing the measurement accuracy.The PIV measurement uncertainty analysis, as an integral part of the measurements, was conducted to assess the confidence in the measurement results. Different approaches were adopted to address different important uncertainty sources in the measurements. In addition, multiple benchmark tests were performed to assess the measurements and to explore the feasibility of the PIV measurements in high void fraction flow conditions. The measured liquid-phase velocity associated with the void fraction distribution measured by a four-sensor conductivity was used to calculate the superficial liquid velocity, which was benchmarked by the flow rate reading from a magnetic flow meter. The results obtained by using the PIV system were quantitatively and qualitatively compared with those obtained in the literature which used different instruments at similar flow conditions. Reasonable agreement was found between the present data and those found in the literature. Extensive data of the liquid-phase turbulence in air-water two-phase flow was acquired using the PIV-PLIF system. The void fraction of the flow conditions varied from 0 to 40% for the circular pipe at OSU and approximately to 60% for the rectangular channel at VT. The flow regimes studied include single-phase, bubbly, cap-bubbly, slug, and churn-turbulent flows with the superficial liquid velocity ranging from 0.5 to 3.4 m/s. The turbulence characteristics include the axial mean velocity, turbulence intensity, axial and radial velocity fluctuation, Reynolds stress, and relative velocity.A liquid-phase turbulence model for two-phase bubbly flows was developed based on the two-phase extension of the single-phase k-e model. Similar to the single-phase k-e model, the two-phase k-e model has all the…
Subjects/Keywords Mechanical Engineering; Two-phase flow; PIV; Turbulence; Void fraction; Measurement; Modeling; Nuclear Engineering
Contributors Sun, Xiaodong (Committee Chair)
Language en
Rights unrestricted ; This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
Country of Publication us
Format application/pdf
Record ID oai:etd.ohiolink.edu:osu1406210359
Repository ohiolink
Date Indexed 2016-12-22
Grantor The Ohio State University

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…Astronautics, Nanjing, China 2013 ...............................................................M.S. Mechanical Engineering, The Ohio State University 2009 to present ..............................................Graduate Research Assistant, Department of…

…Mechanical and Aerospace Engineering, The Ohio State University Publications 1. B. Doup, X. Zhou, I. H. Kim, X. Sun, “Local axial relative velocity measurements in bubbly, cap-bubbly, and slug flows,” Multiphase Sci. Technol. 2014 2. X. Zhou, B. Doup, and X…