Nice to see a working proof of concept. All this is working supersonic, so i might expect metal erosion to cause problems as well. Yet they can keep the burn going and that is a great sign. now we need to see scaling as well.
This promises to make hugely hotter rocket engines on far less fuel. They may even work over a wide range.
All good and we will follow.
World-first "impossible" rotating detonation engine fires up
By Loz Blain
May 04, 2020
A UCF team has produced a continuously firing prototype of a H2/O2 rotating detonation engine, capable of running until the fuel is turned off – a feat previously thought impossible
Professor Kareem Ahmed, University of Central Florida
A Florida team working with the US Air Force claims that it's built and tested an experimental model of a rotating detonation rocket engine, which uses spinning explosions inside a ring channel to create super-efficient thrust.
The vast majority of engines, of course, use combustion rather than detonation to achieve their output goals. Combustion is a relatively slow and controlled process resulting from the reaction between fuel and oxygen at high temperatures, and it's very well understood and mature as a technology.
Detonation, on the other hand, is fast and chaotic and much less predictable. An explosion instead of a burn, it is the massive discharge of energy you get when you break apart the chemical bonds holding an explosive molecule together by giving it a jolt of energy – either electrical or kinetic – in the form of a sufficiently powerful shockwave to destabilize those bonds. Detonation is excellent when you want to wreck stuff in bulk, and much harder to maintain precise control over.
But when you need to break the chains of the Earth's gravity and go to space, every gram of weight makes things that much harder and more expensive. Detonation releases significantly more energy from significantly less fuel mass than combustion, so for more than 60 years, rocket scientists have been working on the idea of a rotating detonation rocket as a potential way to cut down weight and add thrust.
Mechanically simple, the rotating detonation engine is dynamically very complex and requires precise timing and fuel delivery rates
Professor Kareem Ahmed, University of Central Florida
In essence, such a device starts with one cylinder inside another larger one, with a gap between them and some small holes or slits through which a detonation fuel mix can be pushed. Some form of ignition creates a detonation in that annular gap, which creates gases that are pushed out one end of the ring-shaped channel to produce thrust in the opposite direction. But it also creates a shockwave that propagates around the channel at around five times the speed of sound, and that shockwave can be used to ignite more detonations in a self-sustaining, rotating pattern if fuel is added in the right spots at the right times.
Pioneered by engineers at the University of Michigan in the 1950s, the rotating detonation engine is tantalizingly simple in a mechanical sense, but this self-propagating detonation wave has proven torturously difficult to achieve and sustain.
Until now, it seems. A team at the University of Central Florida, working alongside the Rotating Detonation Rocket Engine Program at the Air Force Research Laboratory, claims to have built and tested a working laboratory model. It's a 3-inch copper test rig using a mix of hydrogen and oxygen for fuel, which is the highest-performing rocket fuel for upper stage rocket engines.
"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," says Kareem Ahmed, an assistant professor in UCF's Department of Mechanical and Aerospace Engineering who led the research. "The detonation is sustained continuously until you cut off the fuel. We have tested up to 200 lbf, but the thrust increases linearly with the propellant mass flow."
No comments:
Post a Comment