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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