Film Cooling Applied to a Rotating Detonation Engine

Film cooling has been proposed as a means to keep Rotating Detonation Engine (RDE) hardware cool. There have been some computational investigations showing the benefits of this. Here a small-scale RDE is utilized to evaluate this technology experimentally. Film cooling is applied to the outer wall of the combustion annulus via a pressurized air plenum. This creates a cooling layer between the detonation and the wall to reduce thermal loading. Prior research has shown that the detonation region of the RDE is challenging to film cool due to the high pressures and intense reverse flow. Therefore, the film cooling array starts above the detonation region to not only avoid affecting the detonation characteristics but also to reduce the backflow of hot gases into the coolant plenum. Testing showed that the change in fuel injection scheme had little impact to the operability of the RDE. The film cooled RDE was able to operate at varying equivalence, reactant mass flow, and coolant mass flows. As coolant flow was introduced, the wave speed and frequency remained unchanged. Wall temperature saw reductions with increasing coolant mass flow with diminishing returns when the coolant mass flow was greater than 30% of the reactant flow.