Shock Propagation Through a Square Injector: Investigation into Rotating-Detonation Engine Injector Dynamics

Abstract

The rotating detonation engine is perhaps the most promising means to realize pressure-gain combustion in modern engines. The physical processes underpinning the dynamics of the combustion wave are complex, and a lack of understanding of these processes represents a significant barrier to practical implementation of the technology. A significant simplification of the RDE is considered through an abstracted experimental setup. The detonation wave is replaced with a nonreacting shock generated by a shock tube, and the annulus is unwrapped into a single linear channel. Both simplifications make direct visualization of the problem via schlieren imaging tractable. Several performance metrics are used to relate the fluid-dynamic behavior of the shock–injector interaction to the performance of a theoretical rotating detonation engine. The first such metric is “recovery time,” based on the time taken for the injector to return to a fully flowing state after the passage of a detonation wave. The second such metric not only considers the mass flow through the injector exit but also accounts for potential backflow into the injector nozzle that may occur for sufficiently strong waves. Finally, a reactant mass-deficit metric is used to characterize the reduction in mass injection due to the interaction with the wave.