Taking Rocket Science to a New Level

A team of researchers from the University of Tennessee Space Institute has made a discovery that advances an age-old theorem into new applications and that will land them in the pages of one of the world’s top journals.

Joe Majdalani, a professor at UTSI, worked with Tony Saad, a doctoral student at the institute, on the research, which is published as a review in the Proceedings of the Royal Society A, a highly prestigious journal. Theirs is only the second such review article by Tennessee-based researchers published in the journal’s more than 300-year history.


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Their work began with an examination of how the explosive reaction that powers rockets fueled by solid materials affects the forces inside the motor. It’s a problem that has vexed scientists since the early days of rocketry – the acoustic forces created by the reaction are so powerful that they influence the way energy flows out of the rocket. That energy is what propels the rocket skyward, so controlling that flow is key to making stronger, faster rockets.

What Saad and Majdalani did not expect, though, was that the mathematical underpinnings of their work would lead to an expansion of a theory that has existed since 1856. The theory, developed by famed scientist Lord Kelvin, had never been applied to fluid dynamics, which was the type of analysis the UTSI researchers were using.

In looking at the problem of energy in the rockets, scientists had observed that there was a breaking point of sorts where the energy changed from rotational to irrotational – think of a traditional “on-off” light switch. The UTSI team found, however, that instead of an on-off switch, the change looked more like a dimmer switch, with the energy change happening gradually along a curve instead of instantly.

While that information was interesting, it was the fact that it showed Kelvin’s theory could apply to fluid dynamics that served as the real attraction to reviewers at the journal. Majdalani says being published in the journal is a high honor.

“It’s neat to know we’ve published in what some might call the ‘Bible of science,’” he said. “This is the same journal where the work of scientists like Newton were shared with the world, and that means a lot.”

Majdalani and Saad, who will finish his doctorate this semester, plan to continue their work in hopes of better understanding the multitude of forces involved in rocket motors, with an eye toward even more discoveries down the line.

The article can be found online.

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