Comparative assessment of film cooling strategies for thermal protection of a kerosene-fueled oblique detonation combustor

Thermal protection remains a major challenge for oblique detonation engines (ODEs), whose combustors combine intense heat release with a compact geometry anchored on oblique detonation waves (ODWs). This study numerically investigates the effects of coolant type and mass flow rate on the flow structure, thermal environment, and propulsion performance of a film-cooled kerosene–air ODE combustor at Mach 10 and an altitude of 15 km. Three active cooling strategies are compared under identical geometry and injection conditions: air film cooling, gaseous-kerosene film cooling, and liquid-kerosene mist cooling. Stable, wall-attached oblique-detonation propagation and the canonical wave structure are maintained over the investigated range, while the wave–coolant interaction depends systematically on the coolant medium. Air injection causes greater disturbance to the initiation region and strengthens downstream wave interactions, resulting in the greatest propulsion penalty. The cooling strategies substantially reduce the near-wall thermal load, but produce distinct wall-temperature distributions. Gaseous-kerosene cooling generates a spatially periodic response associated with the discrete injection slots/ports, whereas liquid-kerosene mist cooling produces a smoother and lower near-wall fluid temperature through enhanced two-phase mixing and phase-change heat absorption. Liquid-kerosene mist cooling provides the most favorable balance between thermal protection and propulsion performance at low to moderate injection levels. With further increases in injection level, the thermal benefit approaches saturation while the propulsion penalty continues to increase: the mean near-wall fluid temperature reduction remains approximately 87% across both the inter-slot and cooling-slot wall segments, whereas the total specific impulse is reduced by about 3%–5%. These results quantify the thermal–propulsive trade-off associated with different film-cooling media and demonstrate the potential of fuel-based cooling for thermal management in hypersonic ODE combustors.