Engineers at the University of Central Florida (UCF) are developing technologies that could pave the way for hypersonic flight. They discovered a way to stabilize the detonation needed for hypersonic propulsion by creating a special hypersonic reaction chamber for jet engines.
The new system is capable of accelerating the aircraft at speeds up to 13,000 mph (21,000 km/h), or 17 times the speed of sound, potentially bypassing a hypersonic ramjet. The technology harnesses the power of an oblique detonation wave, which they formed by using an angled ramp inside the reaction chamber to create a detonation-inducing shock wave for propulsion.
An oblique detonation wave engine aims to produce a continuous detonation that’s stable and fixed in space. The technology improves jet propulsion engine efficiency so that more power is generated while using less fuel than traditional propulsion engines, thus lightening the fuel load and reducing costs and emissions.
In addition to faster air travel, this technology can also be used in rockets for space missions to make them lighter, consume less fuel, travel farther, and burn cleaner.
“There is an intensifying international effort to develop robust propulsion systems for the hypersonic and supersonic flight that would allow flight through our atmosphere at very high speeds and also allow efficient entry and exit from planetary atmospheres,” says Kareem Ahmed, an associate professor in UCF’s Department of Mechanical and Aerospace Engineering. “The discovery of stabilizing a detonation – the most powerful form of intense reaction and energy release – has the potential to revolutionize hypersonic propulsion and energy systems.“
Detonation propulsion systems have been studied for over half a century but had not been crowned with success due to the chemical fuel used or the way they were mixed. In previous work by the Ahmed group, this problem was solved by carefully balancing the rate of propellants hydrogen and oxygen released into the engine to create the first experimental evidence of rotating detonation.
However, the short duration of detonation, often as small as microseconds or milliseconds, makes them difficult to study and impractical to use.
In a new study, UCF researchers were able to sustain the duration of the detonation wave for three seconds by creating a new hypersonic reaction chamber, known as the hypersonic high-enthalpy reaction, or HyperREACT. Less than a meter (3.3 ft) long, the HyperReact contains a chamber with a 30-degree angle ramp near the propellent mixing chamber that stabilizes the oblique detonation wave.
“This is the first time a detonation has been shown to be stabilized experimentally,” Ahmed says. “We are finally able to hold the detonation in space in oblique detonation form. It’s almost like freezing an intense explosion in physical space.”
Now the challenge for the developers is to understand how to dynamically change the fuel mixture, flow rate, and tilt angle to maintain stability and controllability of detonation in various conditions.