Experimental investigation of the hydrogen-air rotating detonation engine with cat-ear-shaped film cooling holes

We conduct an experimental investigation on the implementation of cat-ear-shaped film cooling holes for thermal protection in a hydrogen-air rotating detonation engine (RDE). The rotating detonation combustor adopts a cylindrical configuration with 390 cat-ear-shaped film cooling holes densely distributed over its outer wall. We successfully achieve ignition and self-sustained propagation of the rotating detonation wave (RDW) under film cooling conditions, resulting in the RDE producing a supersonic outflow via a Laval nozzle installed at the exit. During operation of the film-cooled RDE, the introduction of cooling air through the film cooling holes leads to an increase in the static pressure of the combustor, and potentially causes up to a 15% variation in RDW propagation velocity, depending on the main flow-based equivalence ratio and the mass flow rate of cooling air. The effect of film cooling on the thrust performance of the RDE is analyzed, and additional cooling air is found to result in an increase in thrust. Periodic blockage of film cooling holes occurs due to RDW propagation, causing an elevation in static pressure within the cooling air chamber. Additionally, as the RDW sweeps across the film cooling holes at a high frequency along the tangential direction, cooling air jets deflect, resulting in distinctive burned traces in areas relative to their proximity to the film cooling holes.