Scientists at the forefront of hypersonic weapons research in China say they have a more powerful revolutionary air-breathing engine. The “revolutionary” air-breathing engine could lift an aircraft from a runway to more than 30km (18.6 miles) into the stratosphere and continuously accelerate it to 16 times the speed of sound. The longest intercontinental flights would take just one or two hours while consuming less fuel compared with conventional jet engines.
The engine blueprint was detailed in a peer-reviewed paper published in the Chinese Journal of Propulsion Technology in December by a team led by Zhang Yining with the Beijing Power Machinery Institute.
According to the China research paper, the engine operates in two distinct modes: below Mach 7 speed, it functions as a continuous rotating detonation engine.
Air from the outside mixes with fuel and is ignited, creating a shock wave that propagates in an annular, or ring-shaped, chamber. The shock wave ignites more fuel during rotation, providing a powerful and continuous thrust for the aircraft.
Above Mach 7, the shock wave stops rotating and focuses on a circular platform at the engine’s rear, maintaining thrust through a nearly straight-line oblique detonation format, according to the paper.
The fuel auto-detonates as it reaches the rear platform because of the very high speed of incoming air. Throughout its operation, the engine relies on detonation as its primary driving force.
Zhang and his colleagues did not disclose the efficiency of the engine in their paper. However, based on previous scientific estimates, the explosion of combustible gases can convert nearly 80 per cent of chemical energy into kinetic energy. Conventional turbofan engines, which rely on slow and gentle combustion, achieve 20-30 per cent efficiencies.
In 2021, University of Florida researchers also had a paper on ways to stabilize the detonation needed for hypersonic propulsion by creating a special hypersonic reaction chamber for jet engines. The system could allow for air travel at speeds of Mach 6 to 17, which is more than 4,600 to 13,000 miles per hour. 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. Unlike rotating detonation waves that spin, oblique detonation waves are stationary and stabilized.
Publicly available information indicates that the Beijing Power Machinery Institute is China’s largest manufacturer of ramjet engines, supplying propulsion systems for the country’s most advanced weapons, including hypersonic missiles.
The PLA’s 93160 unit, headquartered in Beijing and deeply involved in designing the new detonation engine, remains shrouded in secrecy with no publicly available information.
Zhang’s team said the new detonation engine transition was a challenge between the two operating modes: as the speed approached Mach 7, the rotating detonation mode became unsustainable, and the oblique detonation mode had to be ignited within a short time.
The authors said possible solutions to the problem include reducing the incoming air speed from Mach 7 to Mach 4 or lower to allow the fuel to heat sufficiently for auto-ignition.
Slight adjustments to the engine’s internal structure, such as the diameter of the circular platform and the angle of the shock wave tilt, could affect engine performance.
Overall, the engine was not too demanding on operating conditions and could work efficiently in most typical scenarios, they said.
However, the researchers said that relying solely on the paper was not sufficient to produce a practically usable product because they had omitted critical parameters for engineering applications, such as the limited space available for air flow path.
In 2023, China achieved the world’s first flight of a rotating detonation engine on a drone platform. At the powerful hypersonic wind tunnel facility JF-22 in the northern mountainous region of Beijing, scientists have been testing an advanced oblique detonation engine.
SCMP – Explosive engine test with drone could propel China to supersonic age
China’s first drone to be powered by an engine that uses explosions to propel aircraft to unparalleled speeds has made a successful maiden flight at an undisclosed airfield in Gansu province.
The FB-1 Rotating Detonation Engine (FB-1 RDE) was developed jointly by Chongqing University Industrial Technology Research Institute and Thrust-to-Weight Ratio Engine (TWR), a Shenzhen-based private company.
Images circulating online show the engine ignited and tested during the taxiing phase of the drone, which is about five metres (16ft) long. It is unclear whether the engine continued to operate during the flight.
According to a Chongqing Morning News report on Wednesday, the engine ignition experiment was also the drone’s first flight. The craft was developed by the university, with participation by TWR
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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Could be very impactful to electricity markets if the efficiency improvements apply there too.
The best gas fired power plants are ~60% efficient by using a turbine and a heat recovery steam cycle.
Getting to 80% with a single system would be a big deal in countries with expensive fuel or emissions limits.
[ “Zhang and his colleagues did not disclose the efficiency of the engine in their paper. However, based on previous scientific estimates, the explosion of combustible gases can convert nearly 80 per cent of chemical energy into kinetic energy. Conventional turbofan engines, which rely on slow and gentle combustion, achieve 20-30 per cent efficiencies.”
that’s astonishing, with turbofan engines in development (patents) for about ~90yrs.
Working models of (fuel) pulsejet engines had been built ~115yrs ago.
“The first working pulsejet was patented in 1906 by Russian engineer V.V. Karavodin, who completed a working model in 1907. The French inventor Georges Marconnet patented his valveless pulsejet engine in 1908, and Ramon Casanova, in Ripoll, Spain patented a pulsejet in Barcelona in 1917, having constructed one beginning in 1913. Robert Goddard invented a pulsejet engine in 1931, and demonstrated it on a jet-propelled bicycle.”
considering fuel efficiency?
“An ideal PDE design can have a thermodynamic efficiency higher than other designs like turbojets and turbofans because a detonation wave rapidly compresses the mixture and adds heat at constant volume.”
Why is combustion at almost constant volume more efficient (isothermal, higher temperatures?)? ]
Because you extract the work via the change in volume; Work IS force over distance, after all.
Developing some of the force after most of the distance has been traversed is wasteful.
[ Thank You.
With comparable pressures and smaller (compared to already more expanded) volume surface area there’s higher forces (on lower energy input, because of more efficient combustion) and therefore more efficient conversion of chemical to thermal energy (?)
If a comparable amount of the fuel energy is converted into expansion, why does it matter when that fuel&oxidizer volume portion reaches biggest volume (inside the engine)?
Where do jet engines loose that efficiency advantage (top sonic tip speeds limiting compression pressure? material temperature endurance within a more complex combustion chamber?)?
If pressures get equal values why is rapid compression of advantage compared to slower compression?
Would it be correct assuming that a heat signature from detonation engines itself is lower compared to jet engines, but that of the exhaust would(/could?) be more visible?
These are very basic principles and not being looked at that long for to improve seems quite irritating (is science that ‘operationally blind’ over time scales with working specialized within each field of development, at least for known knowledge to public information, e.g. not DARPA or similar)? ]
Nobody is going to develop hypersonic aircraft because they have intrinsically terrible lift to drag – which makes them super fuel-thirsty and short range, and the aerothermal environment becomes insanely expensive to deal with as leading edges at Mach 5 are over 1000°C. The planes would cost billions and can be shot down by million dollar missiles (like patriot), or likely MW lasers in 5-10 years (the time it takes to develop an aircraft).
Aerothermal issues have been solved decades ago.
The planes don’t cost billions.
And apparently everyone is making them.
I worked on X-37B aerothermal and Foyle is correct. Solved does not make it inexpensive.
Congratulations. Well done. We would all want to have a peak in those payload bays.
But… Don’t repeat what you did on the X-37B.
One of the alternatives is a single piece removable metallic alloy shell-heatshield with all movable surfaces at the back end (or CC composite and variants). The shell itself lends itself to rapid fabrication. It is understood that crew has mastered metallurgy, deformation, chemistry, plasma’s. You keep a couple of shells in rotation/repair, while the core structure can fly regularly, outfitted with repaired shells. It beats the shuttle or X-37B turnaround times and reduces it to hours/days, implying you’ll get more missions per year, improving economics.
Given the advancing state of metallurgy, you would have to be very bad at design to get a shell + support interfaces to weigh more than ~ 5000 lbs.
Thanks for sharing Brian. This is really interesting. 2024 will be pretty insane. Many of these “hardware” breakthroughs from 2022/2023 should gone from paper to working machines. It took many years in the past, but now everything is accelerating. R&D budgets are growing rapidly each year.
I think that in 2024 we will finally see stuff which will make us feel like we’re really entered “proper” XXI century.
2024 – new era begins.
Only Asian countries look ar China as a mortal enemy, and,of course their religious minorities,and 99% of their own people.
The US looks at China as a competitor.
The best way to deal with China,in addition to steep tariffs and Biden’s green plans, is to deal sharply and severely with Russia.
We have then surrounded in the South China Sea,thousands of Japanese uninhabited islands available to US armed forces ,as well as Philippines.
India is becoming stronger with the switch to US arms from Russian ones.
But we reserve the right to protect our interests by destroying Chinese armed forces, they continue to kill Americans by the millions just by Fentanyl.
While I’m no CCP fanboy, I don’t blame China for stupid Americans who’s sole purpose in life is their next high.
Whole China may have made some important milestones in this area, it is doubtful they have gotten too far along this area. Rotation detonation engines have become well known in the west recently and suddenly the East is leapfrogging them. Doesn’t sound kosher.
Well, they do have the advantage of a very well developed technical espionage program, which means they have access to our work as soon as we do it, as well as their own. So it’s not entirely implausible. As well, their education system doesn’t waste a lot of time teaching gender ideology instead of thermodynamics.
Command economies are actually pretty good at achieving notable results in limited fields, on account of their being able to direct unreasonable resources to tasks they want done. It’s multitasking that they’re bad at.
It amazes me that so much scientific advancement is achieved when two nations look at each other as mortal enemies.
There is nothing to steal with espionage when you are the leader and producing world’s first and most powerful. When you are already flight testing while your competition is still bench testing, what is there to steal. Constant talk of stealing and espionage is decades old. Besides who do you actually think is the biggest espionage agency in the world. Lol. Its the thief that shouts thief.