Woodruff School of Mechanical Engineering
NRE 8011/8012 and MP 6011/6012 Seminar
Nuclear & Radiological Engineering and Medical Physics Programs
The Leidenfrost Effect Probed by X-rays & A Brief Overview of Argonns Nuclear Engineering Experiments
Dr. Craig Gerardi
Engineering Development & Irradiation Services (EDIS) Department, Argonne National Laboratory
Thursday, March 8, 2018 at 11:00:00 AM
Boggs Building, Room 3-47
Dr. Anna Erickson
Water flows uphill? Liquid nitrogen skitters across a table? A hand immersed in hot molten lead emerges unscathed? Are these cinematic tricks? Are the laws of physics being broken? Alas, science saves the day with a very simple explanation of these phenomena: the Leidenfrost effect. Various aspects of the Leidenfrost effect have been studied since it was first reported by Johann Leidenfrost in 1756. Measurements typically have been performed with zero or small incident velocity. However, in many real-world situations droplets crash into heated surfaces which influences the Leidenfrost temperature and local heat transfer. Models need to be developed to help us understand and control processes such as rewetting of fuel rods in a nuclear power plant during reflooding after the postulated loss-of-coolant-accident where droplets in the dispersed flow regime impact hot cladding. High-speed x-ray full field phase-contrast imaging, a relatively new technique, makes it possible to track dynamic changes in gas-liquid interfaces in real time. The partially coherent x-rays produced by a synchrotron such as the APS can reveal the interface between phases even when the interface is inside a thick liquid medium. This makes it possible to clearly visualize internal vapor generation within a falling droplet at unprecedented speeds and spatial resolutions. These visualizations will be presented and scrutinized during this talk. A brief overview of Argonne’s Nuclear Engineering work with an emphasis on experiments will start the talk.
Dr. Craig Gerardi leads the Engineering Development & Irradiation Services (EDIS) Department. The EDIS Department conducts a wide range of experiments related to nuclear engineering. In addition to reactor safety and development activities, EDIS conducts R&D related to instruments, sensors, and nondestructive evaluation techniques and produces radioisotopes for medical, national security and basic science applications. Dr. Gerardi obtained his Ph.D. and M.S. in Nuclear Science and Engineering from the Massachusetts Institute of Technology and his B.S. degrees in Mechanical Engineering and Nuclear Engineering from the University of Maryland, College Park.
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