Chinese researchers announced they have successfully created the world first hypersonic detonation wave engine that can power planes at Mach 9 (nine times the speed of sound), using cheap jet fuel.
In fact, since the beginning of this year Chinese researchers had been conducting a number of successful ground tests on the oblique detonation engine at the JF-12 hypersonic shock tunnel in Beijing.
Liu Yunfeng, Senior Engineer at the Institute of Mechanics, the Chinese Academy of Sciences, who led the research and tests, published the findings in the peer-reviewed Journal of Experiments in Fluid Mechanics on November 11.
“No test results for [hypersonic detonators using] aviation kerosene have been made before,” said Liu Yunfeng.
A detonation engine can be more efficient and powerful than other hypersonic engines as it can generate sufficient thrust to propel flights at speeds more than Mach 8. While using the same amount of fuel as conventional combustion, the detonation wave can start a series of explosions almost immediately and release more energy.
In fact, scientists in many countries have developed detonation engines, but mainly used hydrogen as fuel, which is far more expensive and has much higher explosion risks.
The fuel, which Liu’s research team uses, is RP-3, a type of jet fuel commonly found at Chinese airports.
“Aeronautical kerosene is the fuel of choice for air-breathing engines (also known as ducted jet engines – Techbiz) due to its high energy density as well as ease of storage and transport,” claimed Liu.
Scientists have attempted to find ways to use jet fuel to power hypersonic flight for decades but igniting kerosene in extremely hot and fast circulating air is way too challenging.
According to Liu, “it’s not easy to detonate”. It is because kerosene burns more slowly than hydrogen, so kerosene-fueled engines often need a longer detonation chamber in order to hold the fuel-air mixture for a longer period of time.
It is estimated that a kerosene-powered engine would require a 10-time longer detonation chamber compared to a hydrogen-powered engine. According to Liu’s research group, it is impossible to lengthen the chamber for most hypersonic aircraft since every millimeter matters.