Comparative Numerical Study of Film Cooling Strategies for Thermal Protection of a Kerosene-Fueled Oblique Detonation Combustor

TL;DR

This study numerically compares three film cooling strategies for kerosene-fueled hypersonic oblique detonation combustors, highlighting their effects on thermal protection and propulsion performance.

Contribution

It introduces a detailed numerical analysis of active film cooling methods, revealing the advantages of fuel-based mist cooling over air cooling in hypersonic ODEs.

Findings

All cooling strategies maintain stable detonation waves.

Mist cooling offers the best thermal protection and performance balance.

Gaseous-kerosene cooling is more effective at higher coolant injection levels.

Abstract

Thermal protection remains a critical challenge for oblique detonation engines (ODEs) operating under hypersonic conditions due to the extreme heat release and compact combustor geometry associated with oblique detonation waves (ODWs). In the present study, the effectiveness of film cooling for a kerosene-air ODE combustor is numerically investigated under a flight Mach number of 10 and an altitude of 15 km. Three active cooling strategies are considered, including air film cooling, gaseous-kerosene film cooling, and liquid-kerosene mist cooling. The results show that all cooling strategies preserve stable oblique-detonation propagation and maintain the canonical wave-system structure within the investigated operating range. Air cooling produces stronger disturbances near the initiation region and triple point, resulting in enhanced downstream wave interactions and larger propulsion penalties. In contrast, fuel-based cooling induces milder disturbances and better preserves the global detonation structure. All cooling methods substantially reduce the near-wall thermal load, although their cooling characteristics differ significantly. Gaseous-kerosene film cooling exhibits a spatially periodic near-wall thermal response associated with the discrete cooling hole arrangement, while liquid-kerosene mist cooling produces a smoother near-wall temperature distribution due to enhanced two-phase mixing and phase-change heat absorption. Among the investigated strategies, mist cooling provides the best overall balance between thermal protection and propulsion performance at coolant mass ratios of 1%-3%, whereas gaseous-kerosene film cooling becomes advantageous at higher injection levels due to improved wall coverage continuity. The present results demonstrate the feasibility and potential of fuel-based film cooling for thermal management in hypersonic ODE combustors.