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UAH aerospace engineering graduate student John Bennewitz, left, and senior aerospace student Jake Cranford with their combustion instability frequency test stand at Johnson Research Center on campus. (Photo by Michael Mercier/UAH)

HUNTSVILLE, Alabama - A Huntsville college student will be in Southern California this week to explain to the rocket engineers at SpaceX his idea for using white noise to dampen dangerous instability in rocket engine firings.

John Bennewitz, a Von Braun Propulsion Scholar at the University of Alabama in Huntsville's Propulsion Research Center, will be at SpaceX's Hawthorne, Ca., campus this Friday. He was invited after presenting two papers on his theory at a national propulsion conference in California this summer.

Bennewitz is interested in the problem of the rapid swings inside a rocket engine caused by fluctuations in propellant flow, acoustics and other variables.

"What can happen is, when you have rough combustion with these instabilities excited at certain frequencies, the oscillations can get so large with amplitudes so great that it destroys the engine," Bennewitz said in a UAH news release. "Combustion instability is one of the largest issues with rocket engine development and design."

Bennewitz's idea was putting a special kind of electric speaker "upstream" of the combustion chamber to broadcast white noise to quieten the instabilities. He designed a model engine with the help of senior aerospace student Jake Cranford and found a "sweet spot" where his white noise suppressed instability.

The two young rocket engineers are now testing narrower frequency bands to find the best range for repressing instability. They hope to get a refined filter built and working so Bennewitz can write a conference paper describing it. He's already a believer in conferences after the one this summer in San Jose where he presented the papers on his work written with faculty advisor Dr. Robert Frederick.

"For me it was very interesting," Bennewitz said, "because now I can tell people it really is worth it to go to these conferences to network with professionals in the industry and get opportunities, such as presenting my research at SpaceX."