Large Eddy Simulation Investigation of Film Cooling in Rotating Detonation Combustors

Abstract High-power density combustors like rotating detonation combustors (RDC) offer significant benefits. However, they must overcome many challenges to be integrated into a gas turbine. Cooling the RDC is one of the most significant, due to the high heat loads generated by the combustion process. Preliminary analysis of the required cooling system has shown that cold-side convective cooling is insufficient to cool combustor walls unless a protective barrier is applied to the hot-side surface. Therefore, this work explores the feasibility of film cooling an RDC. A high-fidelity large eddy simulation investigation was employed due to the uniqueness of this problem. Namely, it was expected that the detonation wave and the downstream oblique shock wave would have a significant impact on the flow exiting cooling holes for this type of combustor. This investigation represents the first attempt to integrate a full coverage film cooling scheme in an RDC. The reference RDC geometry is provided by TU Berlin. Three different coolant plenum pressures were simulated generating three different coolant mass flows in the post-detonation region. The results showed there is a period when each hole is effectively “blocked,” and coolant does not flow out of the hole. As the detonation wave passes, the film is able to recover and reform along the outer wall of the RDC. This process occurs at the detonation frequency of 7.5 kHz creating an unsteady, periodic flow behavior. Overall, the average gas temperature near the wall shows a significant reduction with the use of film cooling. These early results suggest that film cooling can be applied in an RDC flow field.