PERFORMANCE OF COMPOUND ANGLED COOLING HOLES WITHIN A ROTATING DETONATION COMBUSTOR

Abstract

Film cooling is a novel concept for detonation-based combustors. The complexity of the rotating detonation combustor (RDC) flow field poses many challenges for the development of a stable film layer. Moreover, the periodic variations in the flow field alter the film behaviour and reduces cooling effectiveness. The wide variation in freestream gas temperature over the detonation cycle highlight the need to investigate the suitability of existing normalization formulations for these unsteady film cooling cases. In this study, three different adiabatic effectiveness formulations are examined. These provide different insights into coolant traceability and local versus average effects. Both compound-angle holes and shaped holes were analyzed to assess improvements in film effectiveness and hotspot reduction. The results show that compound-angle holes and shaped holes enhance local coolant spreading and help reduce hotspots. The hole compound angle plays a role in coolant dispersion due to variations in the freestream flow angle as the detonation wave moves across the holes. However, in terms of global averages, compounding does not provide significant benefit because the cross stream associated with the tangentially rotating detonation and shock wave dominates the overall flowfield. Nevertheless, film cooling in this transient environment demonstrates a reasonable effectiveness compared to steady non-RDC experiments.