Numerical investigation of circumferentially-inclined film cooling for rotating detonation combustor

The stable operation of rotating detonation engines (RDEs) faces significant thermal protection challenges. Unlike most conventional combustors with purely axial flow, the rotating detonation combustor (RDC) is characterized by a circumferential primary flow induced by the rotating detonation wave (RDW). Therefore, this study proposes a film cooling configuration with combined axial and circumferential injection angles. Numerical simulations are conducted to examine the evolution of the secondary cooling flow and the variation of the film cooling performance under different injection pressures and circumferential angles. Distinct jet behaviors are observed depending on whether the secondary flow is oriented with (co-flow) or against (counter-flow) the RDW propagation. The counter-flow inclination case is found to form an inclined jet that enhances cooling, particularly in the vacuum region between film holes, with performance improving as the inclination angle increases. In contrast, the co-flow inclination case promotes vortex-induced stagnation and wall detachment, reducing both the protected area and temperature drop as the inclination angle increases. The associated increase in coolant mass flow rate is also analyzed for cost efficiency when the secondary flow injection pressure is adjusted to enhance the temperature drop.