UTSA researcher hones spacecraft designs at national lab

Kevin Posladek in front of the Frontier supercomputer.

Editor’s note: This summer, we’re shining a spotlight on Roadrunner researchers and the innovative work they are doing in labs across campus and beyond. Today, we checked in with a student spending his summer working in a National Laboratory.

JULY 28, 2025 — Testing the aerodynamics of rockets in a Mach 7 wind tunnel that emulates the extreme speed of a spacecraft’s descent back to Earth is a highly anticipated assignment among students working in the UTSA Hypersonics Lab.

The task helps to advance the quest for sleeker spacecraft designs and seamless landings. But the rewarding work and fun doesn’t stop there.

Select students also get to work at the Oak Ridge National Laboratory (ORNL), a multiprogram research laboratory in Oak Ridge, Tenn., managed by a nonprofit entity for the Department of Energy. The lab employs a world-class supercomputer to run simulations and discover whether their modeling of physics matches what’s happening in the wind tunnel.

“The research we do has real, practical applications in making space travel safer and more efficient.”

— Kevin Posladek

Kevin Posladek, a PhD candidate in mechanical engineering, began his work in the Hypersonics Lab working under advisor and lab director Christopher Combs, the Dee Howard Endowed Associate Professor in Aerodynamics in the UTSA Department of Mechanical Engineering. He later joined the Graduate Research Program at Oak Ridge.

This experience led Posladek to pivot his research from experimental to computational, and learning the “ins and outs of computer simulations,” he said, seeing a more holistic view of the design process. 

“What I think is most valuable in this program is the exposure to the other half of the research field that I’m in,” Posladek said. “It’s really exciting to have access to some of the best scientists and computational tools in the country to approach the research that I’m passionate about from a new angle.”

Making space travel safer

During summer 2025, Posladek has been particularly focused on the common dangers in space travel, known as shock-shock and shock-boundary-layer interactions.

A shock-shock interaction occurs when two or more shock waves collide, creating new, potentially destructive shock waves, increasing pressure or generating intense heat that could melt a spacecraft.

A shock-boundary-layer interaction occurs when a shock wave hits the air clinging to an object’s surface due to friction. The disruption to this air layer can cause turbulence and drag similar to a hole in the bottom of a sled.

Posladek described the experimental and computational work as operating in tandem with an ongoing feedback loop.

“Computer simulations are a powerful tool for the design of vehicles but these models need to be validated with real-world data so we know that solutions from the computer are reliable,” he said. “That’s where we at UTSA come in — we provide our experimental data to ORNL, and with that, ORNL can validate the computational models that they’ve developed.”

Exploring the physics

The hope is that what takes place in the simulation mirrors what unfolds in the experiment, indicating that both tests have been designed and executed correctly.

“If we see good agreement between the experimental and the simulation data, I will be able to explore the physics further with the results from the simulation, which, if correct, affords a lot more data than I would be able to get in a wind tunnel,” he added.

Posladek hopes that the progress he and his team make this summer at Oak Ridge will support the design of future vehicles.

“Spacecraft reenter Earth’s atmosphere at hypersonic speeds, so the research we do has real, practical applications in making space travel safer and more efficient,” he said.

— Audrey Gray