Numerical analysis of film cooling with microporous walls for rotating detonation engines

Abstract

Thermal protection of the combustor wall under extreme pulsating heat flux is a critical bottleneck for the engineering application of rotating detonation engines (RDEs). Ordinary film-cooling schemes face severe challenges in the strongly unsteady environment of rotating detonation waves (RDWs), including periodic coolant blockage, flow reversal, and cooling film coverage failure. To address these issues, this study proposes an innovative film-cooling scheme based on a microporous wall configuration. Using numerical simulations, the coolant transport mechanisms, reverse-penetration resistance, and overall cooling performance of the micropore configuration under periodic RDW sweeping are systematically investigated. The results indicate that the microporous configuration, by generating a large number of fine, dense jets, significantly enhances the lateral spreading and merging of the coolant along the wall, forming a more continuous, uniform, and wall-attached low-temperature cooling film compared to ordinary round-hole designs. In the critical region where the RDW interacts with oblique shock waves, the microporous configuration demonstrates outstanding resistance to hot-gas reverse penetration, with a significantly lower reverse-flow time fraction than that of conventional round holes. Increasing the coolant mass flow ratio further improves the continuity and integrity of the film coverage, thereby effectively reducing the time-averaged wall temperature and heat flux, though with a slight increase in the peak combustion pressure. Comparative analysis with ordinary round-hole configurations confirms that the microporous design provides clear advantages in reducing the instantaneous peak wall heat flux and improving cooling efficiency uniformity, albeit at the expense of higher instantaneous pressure fluctuations. By refining the flow field and regulating the vortex system, the microporous configuration establishes a more stable and reliable cooling foundation in the vulnerable upstream region, offering an efficient, robust, and less intrusive thermal protection strategy for RDEs.