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Fuel mix boost for rotating detonation rocket engine

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Researchers have experimentally validated the fuel mixture for a rotating detonation rocket engine, an advance that could allow upper stage space rockets become lighter, travel farther, and burn more cleanly.

rotating detonation rocket engine
(Credit: Pixabay)

The advance from a University of Central Florida (UCF) researcher and his team is detailed in Combustion and Flame.

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"The study presents, for the first time, experimental evidence of a safe and functioning hydrogen and oxygen propellant detonation in a rotating detonation rocket engine," said Kareem Ahmed, an assistant professor in UCF's Department of Mechanical and Aerospace Engineering who led the research.

According to UCF, the rotating detonations are continuous, Mach 5 explosions that rotate around the inside of a rocket engine, and the explosions are sustained by feeding hydrogen and oxygen propellant into the system.

This system is said to improve rocket-engine efficiency so that more power is generated while using less fuel than traditional rocket energies.

Mach 5 explosions create bursts of energy that travel 4,500 to 5,600mph and are contained within an engine body constructed of copper and brass.

The technology has been studied since the 1960s but had not been successful due to the chemical propellants used or the ways they were mixed.

"We have to tune the sizes of the jets releasing the propellants to enhance the mixing for a local hydrogen-oxygen mixture," Ahmed said in a statement. "So, when the rotating explosion comes by for this fresh mixture, it's still sustained. Because if you have your composition mixture slightly off, it will tend to deflagrate, or burn slowly instead of detonating."

To record evidence of their finding, the team injected a tracer into the hydrogen fuel flow and quantified the detonation waves using a high-speed camera.

Co-author William Hargus is an advanced propulsion spectroscopist and lead of the US Air Force Research Laboratory's Rotating Detonation Rocket Engine Program.

"These research results already are having repercussions across the international research community," he said. "Several projects are now re-examining hydrogen detonation combustion within rotating detonation rocket engines because of these results. I am very proud to be associated with this high-quality research."