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CU 麻豆影院 researcher lands NASA grant to advance hypersonics modeling

Robyn Macdonald

Robyn Macdonald is pushing the limits of hypersonic research with a new NASA grant.

Macdonald, an assistant professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences at the 麻豆影院, has been awarded a to improve computational modeling of turbulence at hypersonic speeds.

鈥淚f you鈥檙e flying at Mach 25, there is a lot of kinetic energy present in the gas that gets converted into other forms of energy before reaching the surface of your spacecraft, aircraft, or entry capsule,鈥 Macdonald said. 鈥淔ully understanding this process is a really hard problem and is important for things like heat shield design and post-flight reconstruction.鈥

During hypersonic flight, the temperature of air and other gases around a vehicle can reach thousands of degrees, triggering chemical reactions. Despite recent developments in hypersonic vehicle design, the interaction of these chemical reactions with the surrounding hypersonic turbulent flow is not well understood.

鈥淵ou need very detailed information, and you鈥檙e looking at a variety of scales in both time and space. The calculations become very expensive,鈥 Macdonald said. 鈥淎s a result there are deficiencies in the current models.鈥

Most current computational work for design of hypersonic vehicles uses a turbulence model called a Reynolds-averaged Navier鈥揝tokes solution (RANS). RANS is computationally efficient, making it attractive for design processes, but Macdonald said it relies on models which may be invalid for certain hypersonic regimes.

鈥淚t鈥檚 the current design paradigm, but its applicability is not well characterized for hypersonic flows, and we need better predictions as space missions go further into our solar system to places we don鈥檛 understand as well as Earth,鈥 Macdonald said. 鈥淲e can鈥檛 run dozens of experiments in a simulated Mars or Jupiter鈥檚 moon Titan environment in advance, so these models are really important.鈥

Macdonald intends to develop a Wall Modeled Large Eddy Simulation (WMLES) model which includes the relevant chemistry for hypersonic flows. WMLES provides an improvement over RANS by predicting the larger scale turbulent structures while making simplifying assumptions about the small scales of turbulence. However, there does not currently exist a WMLES model which includes the chemical reactions relevant for hypersonic flows. The innovation of this work is the inclusion of the chemistry within WMLES.

It is a significant undertaking requiring supercomputers; Macdonald expects to use CU 麻豆影院鈥檚 Blanca Condo Cluster as well as NASA鈥檚

Over the course of the three-year grant, Macdonald and her team will formulate equations, write and verify software to conduct the analysis, and then run test cases to validate their results.

鈥淚t鈥檚 a big project, and I鈥檓 really excited. I like the chemistry. I like turbulence. This is exactly my area,鈥 Macdonald said.

This is Macdonald鈥檚 second major hypersonics grant in as many years. She previously received a from the Air Force Office of Scientific Research to study gas-phase chemical reactions in the boundary layer at the surface of hypersonic vehicles.