Experimental Investigation of Gaseous Film Cooling for Cylindrical Rotating Detonation Engines

A new combustor has been developed for an experimental test campaign on film cooling for hollow-type Rotating Detonation Engines (RDEs). In support of these research efforts, a modular design has been employed with interchangeable injector manifolds such that a range of coolants, propellants, injection geometries, and operating conditions can be examined. The engine is instrumented with pressure transducers and thermocouples to evaluate performance and heat loads at various locations along the axial direction. High-speed imaging has also been used to study the wave stability, internal combustion structure, and engine ignition process. A parametric study with varying coolant mass flow rate between 5-25% was conducted to characterize the influence of the coolant layer on the engine’s operation. Phase 1 of the study focused on gaseous propellants, utilizing ethylene (C₂H₄) as the fuel, oxygen (O₂) as the oxidizer, and nitrogen (N₂) as an inert coolant. In Phase 2, the investigation shifted to a fuel-based film coolant. Thermocouple measurements revealed a significant reduction in heat flux along the length of the combustion chamber. The highest cooling effectiveness was observed immediately after coolant injection, extending to the region near the wave’s triple point. Stable wave propagation was also observed with a reasonable reduction in engine performance. These initial findings demonstrate the potential of axially injected gaseous film cooling as an effective means of thermal management for RDEs.