We spoke, a few ages ago, of the concept of “oblique detonation engine”a model of reactor that its ardent defenders say can take the propulsion of the future to new heights.
The idea is as simple as it is complex to implement: said engine does not work thanks to a continuous thrust obtained by the combustion of fuel and oxygen, but thanks to the control of a wave of high-frequency detonations, allowing the release of a much more intense energy.
In short, a device or a projectile endowed with such a propulsion would be pushed by a small bomb with infinite repetition, so to speak stuck to its ass.
For the moment, the hopes of the hypersonic —these objects capable of reaching a speed greater than five times the speed of sound, i.e. more than Mach 5—rely above all on the “scramjet» or ramjetan evolution of the conventional ramjets fitted to most modern jets or missiles.
Most of these scramjets run on hydrogen, an efficient fuel that is complex to store, handle and operate, and presents a high risk of explosion.
Faster, cheaper
But like reports the South China Morning PostChinese scientists claim to have successfully tested a hypersonic detonation engine capable of reaching Mach 9, powered not by hydrogen but by kerosene, the same type of fuel that powers the engines of typical aircraft, including including the ones you can take out into the sun.
Under the aegis of researcher Liu Yunfeng, the trial was reportedly carried out earlier in the JF-12 Shock Tunnel, where the conditions of a hypersonic flight can be reproduced. These results were published in the Chinese Journal of Experiments in Fluid Mechanics.
“Kerosene is the fuel of choice for air-powered jet engines”y écrit Liu Yunfeng. “It is not easy to blow up”he continues, which is why he has long been dismissed for the detonation reactor.
As Interesting Engineering explains, the problem was related to the ability to detonate kerosene in hypersonic conditions, with air that is both very hot and very mobile. In addition, the detonation chamber would have required a size ten times larger than that intended for hydrogen – an obviously thorny problem for a flying machine.
Liu Yunfeng and the scientists of his team seem to have found a simple solution to put in place: a simple physical asperity of a few centimeters placed in the combustion chamber, dramatically increasing the ability of kerosene to detonate, even under supersonic conditions.
In the future, this type of reactor, thanks to the use of this relatively inexpensive fuel, simple to handle and already ubiquitous, might be used to equip military vehicles, but also in the civilian sector. One can thus dream of flying at hypersonic speeds cargo or passenger aircraft.
However, this future seems very distant: Liu Yunfeng himself admits, despite the certain importance of his discoveries, that this technology is still far from being sufficiently mature and inexpensive to find a commercial application.
