Rotating Detonation Rocket Engine Operability Under Varied Pressure Drop Injection

Abstract

Rotating detonation rocket engine (RDRE) experiments have so far been limited to injectors with high pressure drop to limit injector–plenum coupling. However, this corresponds to a reduction in the potential performance benefits of RDREs. To investigate this phenomenon, two injection configurations with different total injection areas are compared with respect to overall engine operability, global performance, and steady-state wave propagation. Notably, the increased area corresponds with a three to four times decrease in pressure drop, with negligible effects on operability and performance. The RDRE is found to operate in a detonative mode for both injectors across equivalence ratios between 0.6 and 2.5, and total mass flows between 0.09 and . The steady-state wave propagation varies significantly between the two injectors, with low pressure drop injection sustaining fewer waves traveling at higher velocities at the maximum performance conditions, but in all other conditions promoted lower wave speeds and counter-propagating behavior, denoting a breakdown in the steady wave propagation. This breakdown is likely due to increased injector–plenum coupling. These results provide insight into the effects of reduced pressure drop on the operation of an RDRE, and indicate challenges that must be overcome in the design of real systems that include RDREs.