Experimental Development of Gaseous Propellant Mono-Cylindrical Rotating Detonation Engine Film Cooling

Thermal management remains one of the critical challenges in the advancement of rotating detonation engine (RDE) technology for practical propulsion applications. To facilitate progress in this field, this study investigates the use of gaseous film cooling via axial injectors, aiming to characterize its influence on engine operation and cooling effectiveness. Experiments were conducted using a combination of gaseous oxygen and ethylene as propellants. This investigation comprises two stages: the initial phase employed an inert film coolant, specifically nitrogen, before transitioning to a fuel-based coolant utilizing ethylene. For each stage, a parametric study was conducted with coolant mass fractions of up to 23%. Across the 35 short-duration test fires conducted, stable wave propagation was sustained even with the introduction of film cooling. Performance degradation in specific impulse and characteristic velocity remained within acceptable limits of up to 29%, while heat flux was reduced by up to 34%. More importantly, the region surrounding the wave propagation zone, where heat loads were highest, was effectively reduced using this architecture. These findings demonstrate the potential of axially injected gaseous film cooling as an effective thermal management strategy for RDEs.