China announced successful experiments with the first oblique detonation engine (ODE) powered by standard RP-3 aviation kerosene, marking a potential game-changer in hypersonic propulsion, reported South China Morning Post on Feb. 26. The experiments were conducted at Beijing’s JF-12 shock tunnel, the world’s highest velocity wind tunnel.
Hypersonic vehicles are normally fueled by hydrogen or ethylene, which are highly flammable and have difficult storage requirements. RP-3 kerosene is readily available and is easily stored, and is also ideal, with higher energy density. The team has overcome RP-3’s long ignition delays, which would make it difficult to start mid-flight, a critical feature for future hypersonic vehicles, by pre-compressing the mixture to 3,800 Kelvin (3,527° Celsius) before ignition. The team has also created localized “hot spots” by using small bumps and winged-shaped struts to accelerate fuel dispersion, which allows the engine to start mid-flight. The engine creates self-sustaining “detonation diamonds,” ultra-fast shock-wave explosions that complete the combustion process in microseconds. The shock wave compresses and ignites the air mixture with such intensity that it forms a self-reinforcing explosion front.
