Researchers have developed a rocket propulsion system, known as a rotating detonation rocket engine, that will allow upper stage rockets for space missions to become lighter, travel farther, and burn more cleanly.
Rotating detonations are continuous, Mach 5 explosions that rotate around the inside of a rocket engine. The explosions are sustained by feeding hydrogen and oxygen propellant into the system at just the right amounts. This system improves rocket engine efficiency so that more power is generated while using less fuel than traditional rocket energies, thus lightening the rocket's load and reducing its costs and emissions.
Mach 5 explosions create bursts of energy that travel 4,500 to 5,600 miles per hour, which is more than five times the speed of sound. They are contained within a durable engine body constructed of copper and brass. The technology, studied since the 1960s, had not been successful due to the chemical propellants used or how they were mixed.
The researchers carefully balanced the rate of the hydrogen and oxygen propellants released into the engine. They had to tune the sizes of the jets releasing the propellants to enhance the mixing for a local hydrogen-oxygen mixture so when the rotating explosion comes by for this fresh mixture, it's still sustained. If the composition mixture is off slightly, it will tend to deflagrate, or burn slowly, instead of detonating.
To demonstrate the method, the team injected a tracer in the hydrogen fuel flow and quantified the detonation waves using a high-speed camera.