威尼斯娱人城官网

Title： Recent Advances in Two-phase Flow Measurement Techniques
Speaker： Yang Liu, Ph.D
Host： Yin Junlian, Associate Professor
Place： F310, School of Mechanical Engineering
Time： 14：00 to 16：00, Jun 16, 2017

Abstract：
High quality two-phase flow data is important for developing advanced two-phase flow models, as well as for validating these models.  However, accurate measurement of two-phase flow has remained as a challenging task for many decades due to complex interfacial structure.  In this talk, several techniques recently developed to tackle this challenge will be introduced.  The first technique is based on high speed optical imaging system and advanced image processing algorithms.  A comprehensive image processing package has been developed to deal with issues such as separation of overlapping bubbles, 2-D outline reconstruction, 3-D shape reconstruction, bubble tracking, and identification of bubble interaction mechanism.  Time resolved 3-D bubble information could be obtained using this method for low void fraction bubbly flows.  The second technique is based on fast X-ray densitometer system.  High resolution linear detector arrays are used in this system, which could yield direct void fraction measurement along the X-ray beam path.  Several practical issues such as x-ray energy spectrum will be discussed.  The last topic introduced here is about the uncertainty quantification of the multi-sensor conductivity probe.  In this study, the uncertainty sources involved in probe fabrication, signal processing, and measurement models are integrated into a single framework based on the Monte Carlo method.  The uncertainty of a practical measurement can be predicted by this framework based on the specific measuring parameters such as test section dimension, measuring location, probe configuration, flow condition, bubble size, shape and velocity fluctuation.  It is expected that various two-phase flow regimes can be measured more accurately with these newly developed measuring techniques.
 
Biography：
Dr. Yang Liu is an assistant professor of the Mechanical Engineering Department at Virginia Tech.  Prior to his current position, he was a postdoctoral research associate in the Thermal-hydraulics and Reactor Safety Laboratory at Purdue University.  In recent years, he has conducted researches in nuclear reactor thermal hydraulics, multiphase flow and heat transfer, fast X-ray densitometry, and high speed optical imaging, etc. He has authored/co-authored more than 60 research publications in international journals and conferences. Dr. Liu received his B.S. in 2000, M.S. in 2003 from Shanghai Jiao Tong University, and his Ph.D. in 2008 from Purdue University, all in nuclear engineering.