Enhancing thermal performance of jet-regeneration composite cooling systems: An analysis of flow mode and distribution utilizing supercritical n-decane and ambient air

To enhance the heat transfer performance of the scramjet, this paper conducts research and analysis on the impact of flow mode and flow distribution of supercritical n-decane and ambient air on flow and heat transfer characteristics, based on regeneration cooling channels. Given the disparities in fluid flow characteristics within the channel, the three flow configurations exhibit varying degrees of heat transfer deterioration. In the jet single outlet flow mode, the fluid mobility within the channel is relatively poor, leading to the most pronounced deterioration of heat transfer. The combined heat transfer performance between the jet fluid and the crossflow fluid is predominantly influenced by the number of jets and the distribution ratio of flow rates. Notably, the jet-crossflow single outlet arrangement exhibits exceptional heat transfer capabilities when the jet flow rate constitutes a relatively low proportion (12.5 %) while the crossflow flow rate is substantial (87.5 %). Ambient air, with its lower density, arrives at the heated surface with significantly higher velocities and greater turbulence intensity compared to supercritical n-decane. As the number of jet holes increases, the inhomogeneity (R) in the Nusselt number gradually diminishes. For most configurations, R is more pronounced in ambient air than in supercritical n-decane.