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This summer, Delaney Baumberger, a mechanical engineering graduate student at �ձ�av��Ƶ, spent ten weeks working among some of the nation’s top aerospace scientists at the Air Force Research Lab in Dayton, Ohio.

Baumberger and her adviser, associate professor Jeffrey Doom, collaborated with Air Force Research Lab researchers to run advanced computational fluid dynamics simulations for hypersonic scramjet engines, experimental engines that burn fuel at speeds above Mach 5. Their work explored how engine geometry affects combustion stability and performance at extreme speeds.

Doom, who also coordinates �ձ�av��Ƶ’s aerospace engineering program, has participated in the lab’s Summer Faculty Fellowship for the past five years. This summer marked only the second time he’s had a student join him for the prestigious program, the first being Zachary Chapman in 2021 and 2022.

Simulations focused on engine cavity design

From June 2 through Aug. 8, Baumberger and Doom worked on the Wright-Patterson Air Force Base, one of the largest and most active Air Force facilities in the country. They focused on how the length of the scramjet engine’s cavity, a recessed section that helps stabilize the flame, affects where and how combustion occurs.

The Air Force provided experimental data for cavity lengths of 76, 114, and 142 millimeters, but lacked information for longer configurations. Baumberger and Doom filled that gap by running simulations for lengths up to 228 millimeters. Their models used a cavity depth of 19 millimeters, allowing them to isolate how the length-to-depth ratio influences flame behavior, pressure and airflow.

Using STAR-CCM+, the same computational fluid dynamics software available in �ձ�av��Ƶ’s lab, they were able to simulate realistic flight conditions using high-performance computing clusters. “Early on, results could take five or six hours to process,” Baumberger said. “Once we refined the mesh, up to a couple million cells, it sometimes took a week or more to complete a single sim.”

Like pixels on a screen, smaller computational cells produce more detailed results, she explained. Throughout the summer, Doom and Baumberger regularly presented updates in weekly meetings with research lab mentors and other research interns working on related projects.

The simulations revealed that the fuel equivalence ratio, the amount of fuel compared to air, has a far greater influence on combustion and pressure than cavity geometry. When the right fuel amount is used, the flame stays anchored inside the cavity, producing stable, efficient combustion. Meanwhile, cavity shape mainly affects airflow when there is no combustion occurring.

NASA project launches aerospace research interest

Baumberger first gained an interest in aerospace research when she was team lead in a NASA contest under the supervision of associate professor Todd Letcher. 

For her senior design project, Baumberger worked with two other seniors to create the rover POSEID-N (Prospecting Observation System for Exploration, Investigation, Discovery, and Navigation). It was one of 14 finalists that competed in Cocoa Beach, Florida, June 10-12, 2024, finishing third overall and being honored for having the best prototype.

That experience led her to join Doom’s lab, where she began working on scramjet engine simulations. 

During the 2024–25 school year, she compared hydrogen and ethylene fuels for hypersonic applications. Hydrogen, she found, burns faster and cleaner, making it ideal for high-speed engines that require quick combustion. Her work, “CFD Comparison of Hydrogen and Ethylene Fuel in Hypersonic Scramjets,” earned first place at �ձ�av��Ƶ’s Graduate Research, Scholarship and Creative Activity Day in spring 2025.

Baumberger will present that project at the American Institute of Aeronautics and Astronautics SciTech Forum in January and hopes to present her research from this summer at the AIAA Aviation Conference in Las Vegas next July.

Looking for a career close to home

A Blair, Nebraska, native, Baumberger will graduate with her master’s degree in December and she hopes to find a position in private industry close to South Dakota.

“The hardest part of the summer was being so far from home,” she said. “Even though Ohio is still in the Midwest, it felt pretty far from South Dakota. But working with top Air Force engineers and using cutting-edge research tools was an amazing experience.”

Outside of research, Baumberger and Doom toured the NASA Glenn Research Center’s Neil Armstrong Test Facility in Sandusky, Ohio, and visited wind tunnels at Ohio State University. They also made several trips to the nearby National Museum of the U.S. Air Force, one of the world’s largest aviation museums.

“It was humongous,” Baumberger said. “You could spend days there and still not see everything.”