Nuclear Engineering and Engineering Physics
Visualization of data from a new light-extinction technique for the measurement of the 2-D distribution of void fraction in air-injected water. (44K JPG)
Characterizing stress in structural systems
Associate Professor Daniel C. Kammer is developing new methods to measure and characterize the stresses placed on structural systems in order to reduce the need for expensive and time consuming experimental testing. In studying automobile durability, load transducers are used to measure forces applied to vehicles in operation. However, the transducer can change the structural characteristics of the system, resulting in inaccurate force predictions. In other cases, the area subjected to forces may be inaccessible for measurement. Through determining accurate forcing functions, greater reliance can be placed on numerical simulation based upon analytical models. These models could then be used to reconstruct the forces applied to the vehicle based upon measuring the subsequent structural response. In effect, the vehicle could become its own force transducer.
MEDUSA lives; PEGASUS is coming
In 1992, undergraduates in Professor Raymond J. Fonck's introductory nuclear engineering course started building a tokamak. A tokamak consists of a set of current-carrying coils which produces a "magnetic bottle" for confining hot doughnut-shaped plasmas used in fusion energy research. Thanks to the volunteer efforts of many, students are now collecting data from MEDUSA (major radius = 10-15 cm., aspect ratio = 1.5, plasma current = kA). Student presentations at academic conferences have earned international recognition for the device. The success of MEDUSA helped secure funding to build PEGASUS (major radius = 45 cm., aspect ratio = 1.1-2, and plasma current = 100-400 kA).
Vapor explosions break down toxic waste
Wisconsin Distinguished Professor Michael L. Corradini and Assistant Professor Riccardo Bonazza continue their study of vapor explosions as related to developing an industrial waste-processing technique. The team injects a water solution of toxic organic compounds into a pool of molten iron to use thermal shock and the catalytic action of iron to chemically crack down toxic compounds into their harmless components. The mechanisms of explosive vaporization, and the thermophysical conditions under which a mechanical explosion occurs, are studied. In a cryogenic simulation experiment, Bonazza looks at the interaction of hot water with different types of refrigerant, using a light-extinction technique.
Limiting risk in nuclear power plants
Corradini and Bonazza are also investigating "vapor explosion" as a risk to nuclear power plants that use molten metal as a coolant and water to transfer heat to turbines. Usually, the energy exchange is controlled. But under certain conditions--which the researchers are attempting to characterize and thus avoid--the metal breaks up too quickly and all of the heat transfers in a fraction of a second. "When you transfer energy that fast--when you make steam that fast--it pressurizes. To the naked eye it looks like a chemical explosion," Corradini explains. To understand the fluid mechanics and energy transfer during the mixing process between the waste stream and molten metal catalyst, Corradini and Bonazza are conducting experiments (which currently don't include waste materials) at the university's Synchrotron Radiation Center. There they've installed a $600,000 high-energy X-ray source that allows them to observe the process in real time. "We are essentially imaging this whole process," Corradini says, "so we can literally see inside the molten pool."
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1996 Annual Report Contents