A team of Chinese engineers created an advanced engine that operates in two modes, allowing the aircraft to travel at 19,756 km/h at an altitude of 30 km.
A NASA rotary engine in action during a test. Photo: NASA
Chinese hypersonic weapons researchers have developed the world's most powerful rotary engine, Interesting Engineering reported on December 27. Described as a revolutionary design, the new rotary engine can take aircraft to an altitude of 30 km and travel at Mach 16 (19,756 km/h). At this speed, an intercontinental flight would take just a few hours and consume much less fuel than a conventional jet engine.
Designed by Zhang Yining and colleagues at the Beijing Institute of Machinery, information about the engine was shared in a paper published in the Chinese journal Propulsion Technology in December. The engine operates in two modes, the first at a speed below Mach 7 (8,643 km/h), operating as a rotating continuous combustion engine (RDE). Outside air mixes with fuel and is burned, creating a shock wave. This shock wave spreads out in the annular chamber. During rotation, the shock wave burns more fuel, resulting in a strong and continuous thrust for the aircraft.
In the second mode, when the aircraft is traveling at speeds above Mach 7, the shock wave stops rotating and focuses on the circular platform at the rear of the engine. This helps maintain thrust through a nearly straight-line indirect detonation pattern. As the team describes, the fuel self-detonates as it approaches the rear platform due to the high velocity of the incoming air. The engine relies on detonation as its primary thrust throughout its operation.
Zhang and his colleagues did not disclose the efficiency of their engine in their research paper. However, based on previous scientific estimates, the detonation of combustible gas can convert nearly 80% of the chemical energy into kinetic energy. This is a significant improvement over conventional turbofan engines, which typically achieve efficiencies of 20-30% and rely on slow, gentle combustion. Zhang’s team says their design combines rotational detonation and linear detonation at multiple speeds. This approach has many advantages, and can improve the efficiency of the optimal thermodynamic cycle at nearly every speed range.
According to the scientists, the transition to the new combustion engine is difficult because of the two operating modes. As the speed approaches Mach 7, the rotary detonation mode becomes unstable. Therefore, the indirect detonation mode needs to be fired quickly. One solution is to reduce the air intake speed from Mach 7 to Mach 4 (4,939 km/h) or even lower. This will allow the fuel to heat up enough to self-ignite. Another solution is to make slight adjustments to the internal structure of the engine, such as changing the diameter of the circular base and the angle of the shock wave. Such changes can affect the overall performance of the engine. According to the research team, the new engine does not require specialized operating conditions and can operate efficiently in most cases.
An Khang (According to Interesting Engineering )
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