A ΒιΆΉΣ³»΄«Γ½ researcher and his team have developed an advanced new rocket-propulsion system once thought to be impossible.
The system, known as a rotating detonation rocket engine, will allow upper stage rockets for space missions to become lighter, travel farther, and burn more cleanly.
The results were published this month in the journal .
βThe study presents, for the first time, experimental evidence of a safe and functioning hydrogen and oxygen propellant detonation in a rotating detonation rocket engine,β says Kareem Ahmed, an assistant professor in ΒιΆΉΣ³»΄«Γ½βs Department of Mechanical and Aerospace Engineering who led the research.
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 at just the right amounts.
This system improves rocket-engine efficiency so that more power is generated while using less fuel than traditional rocket energies, thus lightening the rocketβs load and reducing its costs and emissions.
This system improves rocket-engine efficiency so that more power is generated while using less fuel than traditional rocket energies, thus lightening the rocketβs load and reducing its costs and emissions.
Mach 5 explosions create bursts of energy that travel 4,500 to 5,600 miles per hour, which is more than five times the speed of sound. They are contained within a durable 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.
Ahmedβs group made it work by carefully balancing the rate of the propellants, hydrogen and oxygen, released into the engine.
βWe have to tune the sizes of the jets releasing the propellants to enhance the mixing for a local hydrogen-oxygen mixture,β Ahmed says. βSo, 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.β
Ahmedβs team also had to capture evidence of their finding. They did this by injecting a tracer in the hydrogen fuel flow and quantifying the detonation waves using a high-speed camera.
βYou need the tracer to actually see that explosion that is happening inside and track its motion,β he says. βDeveloping this method to characterize the detonation wave dynamics is another contribution of this article.β
William Hargus, lead of the Air Force Research Laboratoryβs Rotating Detonation Rocket Engine Program, is a co-author of the study and began working with Ahmed on the project last summer.
βAs an advanced propulsion spectroscopist, I recognized some of the unique challenges in the observation of hydrogen-detonation structures,β Hargus says. βAfter consulting with Professor Ahmed, we were able to formulate a slightly modified experimental apparatus that significantly increased the relevant signal strength.β
βThese research results already are having repercussions across the international research community,β Hargus says. βSeveral 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.β
βThese research results already are having repercussions across the international research community.β β William Hargus, study co-author
The study was supported with funding from the U.S. Air Force Office of Scientific Research and an Air Force Research Laboratory Contract.
Co-authors included Jonathan Sosa, a postdoctoral research scientist with ΒιΆΉΣ³»΄«Γ½βs Propulsion and Energy Research Laboratory; Robert Burke, a doctoral candidate in ΒιΆΉΣ³»΄«Γ½βs Department of Mechanical and Aerospace Engineering; Daniel J. Micka with Creare, LLC; and John W. Bennewitz, Stephen A. Danczyk and Eric J. Paulson with the U.S. Air Force Research Laboratory.
The research was performed at ΒιΆΉΣ³»΄«Γ½βs Propulsion and Energy Research Laboratory.
Ahmed earned his doctoral degree in mechanical engineering from University at BuffaloΒ β The State University of New York. He worked at Pratt & Whitney Military Engines andΒ Old Dominion University prior to joining ΒιΆΉΣ³»΄«Γ½βs Department of Mechanical and Aerospace Engineering, part of ΒιΆΉΣ³»΄«Γ½βs College of Engineering and Computer Science, in 2015. He is the director of ΒιΆΉΣ³»΄«Γ½βs Propulsion and Energy Research Laboratory, a faculty member of ΒιΆΉΣ³»΄«Γ½βs Center for Advanced Turbomachinery and Energy Research, associate fellow of the American Institute of Aeronautics and Astronautics, AFRL Faculty Research Fellow, and a member of ΒιΆΉΣ³»΄«Γ½βs Renewable Energy and Chemical Transformation Cluster.
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