A team of Chinese engineers has created an advanced dual-mode engine that allows aircraft to travel at 19,756 km/h at an altitude of 30 km.
A NASA rotary internal combustion engine in operation during testing. Photo: NASA
Chinese hypersonic weapons researchers have developed the world's most powerful rotary explosive engine, Interesting Engineering reported on December 27. Described as a revolutionary design, the new rotary explosive engine could propel aircraft to altitudes of 30 km and travel at Mach 16 (19,756 km/h). At this speed, intercontinental flight would take only a few hours and consume significantly less fuel than conventional jet engines.
Designed by Zhang Yining and colleagues at the Beijing Institute of Machinery, information about the engine was shared in a December article in China's Propulsion Technology journal. The engine operates in two modes; the first, at speeds below Mach 7 (8,643 km/h), functions as a continuously rotating internal combustion engine (RDE). Outside air mixes with fuel and is burned, creating a shock wave. This shock wave propagates within the annular chamber. During rotation, the shock wave burns more fuel, resulting in strong and continuous thrust for the aircraft.
In the second mode, when the aircraft is moving at speeds above Mach 7, the shock wave stops rotating and focuses on a circular platform at the rear of the engine. This helps maintain thrust through an indirect explosion in a nearly linear fashion. As the research team describes, the fuel self-ignites as it approaches the rear platform due to the high speed of the incoming air. The engine relies on this detonation as its primary thrust throughout operation.
Zhang and his colleagues did not disclose the engine's efficiency in the research paper. However, based on previous scientific estimates, explosive flammable gases can convert nearly 80% of their chemical energy into kinetic energy. This is a significant improvement over conventional turbofan engines, which typically achieve 20-30% efficiency, relying on slow and gentle combustion. Zhang's research team stated that their design combines rotary detonation and linear detonation at various speeds. This solution offers several advantages, potentially improving the optimal thermodynamic cycle efficiency across almost any speed range.
According to the scientists, switching to the new internal combustion engine is difficult due to its two operating modes. When speeds approach Mach 7, the rotary ignition mode becomes less sustainable. Therefore, the indirect ignition mode needs to be quickly triggered. One solution is to reduce the incoming air velocity from Mach 7 to Mach 4 (4,939 km/h) or even lower. This would allow the fuel to heat up sufficiently to self-ignite. Another solution is to slightly adjust the engine's internal structure, such as changing the diameter of the circular chamber and the angle of the shock wave. Such changes could affect the engine's overall performance. 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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