College of Engineering

The 22-foot high wind tunnel facility in USU’s Technology Building is Mechanical and Aerospace Engineering Associate Professor Barton Smith’s most valuable facility for his research on nuclear thermal-hydraulics.

In September, Smith received a $635,000 grant from the Department of Energy for his research project “Transient Mixed Convection Validation for NGNP,” which focuses on providing data for engineers who simulate nuclear reactors. The wind tunnel allows Smith and his research team to collect information vital for testing critical computer simulations of accidents at nuclear plants. The team includes Ph.D. students Jeff Harris and Brandon Wilson, MS student Blake Lance, and undergraduate Vardan Semerjyan. Ultimately, this project lends to the construction and improvement of nuclear plants, making them more safe and cost efficient.

“Plant vendors, regulators, and researchers run computer simulations to ensure that a plant is safe. They simulate the worst-case scenario whenever they are not sure they can model accurately. Newer models may be more accurate and can be less conservative, but they need to be tested by comparing them to experimental data” Smith said.

“While computer models are always progressing, simulating the motion of gas or liquids remains a difficult challenge. We think computers are so powerful, but it is unlikely that a perfectly accurate computer model will ever exist” Smith said. “Experiments like this one help us to find the flaws in computer models and to fix them.”

 By shining a laser sheet at particles in the see-through test section located in the center of the wind tunnel and then photographing their motion, the researchers can measure the wind velocity inside the wind tunnel. They can also measure how much heat is entering the wind tunnel through a heated wall. Each of these results can be compared to computer models of the flow. The process of comparing a computer simulation model to experimental data is called “validation.”

One unique feature of the wind tunnel is that it generates “mixed convection.” A hot object will cool itself due to “natural convection,” or the tendency of heated air to rise. The same object can be cooled by using an airmover (fan, blower) to force air to flow over it, or, in other words, using “forced convection.” In mixed convection, the forced air motion and the rising heat each play a role. Nuclear plants normally run under forced convection. Mixed convection is an important flow regime to simulate since, in nuclear plants in the event of a pump failure the coolant flow will go from forced, to mixed, to natural convection in that event.

The DOE is interested in new thermal-hydraulic validation data to help vendors and regulators in their new designs and safety analyses.

Smith has a similar project funded by Bettis Marine Propulsion Laboratory (who build Naval nuclear reactors) as well as a project aimed at building a web-accessible database for validation data funded by Idaho National Laboratory (INL).