Woodruff School of Mechanical Engineering
Faculty Candidate Seminar
Mechanistic Modeling of Flow Regime Transition in Gas-liquid Two-phase Flows
Dr. Xiaodong Sun
The Ohio State University
Thursday, October 16, 2014 at 11:00:00 AM
MRDC Building, Room 4211
In modeling gas-liquid two-phase flows, flow regime-dependent correlations/models are used as constitutive relations to close the two-phase flow models, such as the two-fluid model. Consequently, flow regime transition models/criteria are necessary to identify flow regimes in nuclear reactor safety analysis codes. These models/criteria were historically developed for quasi fully-developed flows and therefore do not account for the dynamic nature of the flows due to bubble interactions and phase change. This shortcoming would lead to large errors and sometime numerical challenges. In the literature, interfacial area transport equation (IATE) was proposed to address this issue. This seminar will provide an overview of the development effort of IATE. Emphasis will be placed on the modeling of bubble interactions, and research needs and challenges, including the needs of experimental data and mechanistic model for two-phase flow turbulence, in particular for flows of high void fractions, such as cap-bubbly, slug, and churn-turbulent flows. Some of our recent work performed for air-water two-phase flows using a particle image velocimetry system to obtain local liquid velocity and turbulence data will be reported, together with the measurements for the gas phase to obtain local void fraction, bubble size, and bubble velocity. In addition, preliminary work on dynamic flow regime transition identification will be discussed to show the potential of the two-group IATE approach.
Xiaodong Sun is an associate professor of Nuclear and Mechanical Engineering at The Ohio State University. Dr. Sun received his B.S. in Thermal Engineering and MSNE from Shanghai Jiao Tong University, China, and MSME and Ph.D. in Nuclear Engineering from Purdue University. Dr. Sun then stayed at Purdue University as a postdoctoral researcher before he joined OSU in 2004. Dr. Sunís research interest areas include reactor thermal hydraulics and safety; two-phase flow experimentation, modeling, and numerical simulation; thermal hydraulics in advanced nuclear reactors; and heat exchangers for high-temperature reactor applications. Dr. Sun has co-authored over 45 journal articles and 110 conference papers. He was chair of the American Nuclear Societyís Thermal Hydraulics Division (2012-2013) and has been serving as chair of the Divisionís Program Committee since June 2013. Dr. Sun was the technical program chair for the ANS 2012 Winter Meeting and is slated to serve as technical program co-chair for the 10th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-10) and the 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16).
Refreshments will be served.