More fuel-efficient and lightweight rockets for future spacecraft might be realized with a new type of engine designed at the University of Washington. The rotating detonation engine (RDE) is propelled by shock waves in a thrust mechanism that eliminates the need for many conventional engine components.

Instead of burning propellant and directing it out of the back of the engine to create thrust, the RDE uses Section view of the RDE. Gaseous methane and oxygen are directed into a narrow annular gap through a set of propellant injectors. A spark plug ignites the mixture, which rapidly transitions to circumferentially traveling detonation waves. Source: James Koch et al., University of Washingtonconcentric cylinders to direct propellant flow into a narrow annular gap where ignition occurs, heat is rapidly released to form a shock wave and a strong pulse of gas is generated with significantly higher pressure and temperature that is moving faster than the speed of sound.

Modeling and experimental analyses were conducted to better understand the nature and control of these thrust-producing detonations. Combustion processes in an experimental engine were recorded with a high-speed camera, and the resulting observations were used to devise mathematic models describing detonation dynamics and wave formation phenomena.

Videos taken during laboratory tests document propellant flows in the gap between the cylinders, and, after ignition, the formation of a shock wave induced by rapid heat release. Stable combustion pulses were then observed to form and continue to consume available propellant.

The research described in Physical Review E will lead to improved performance and stability for future RDE designs.