Experimental and numerical investigation of flow dynamics and thermal behavior of supercritical n-decane in jet-regeneration composite cooling technology for scramjet engines

Traditional regenerative cooling methods fall short of meeting the thermal dissipation demands when the scramjet is flying at higher Mach numbers. In this paper, jet cooling is employed for the thermal management of scramjets, leveraging its exceptional thermal dissipation capabilities in environments with intense heat flux. Liquid crystal thermography technology was utilized to experimentally study the thermal exchange behaviors of the ambient air under varying conditions including different numbers of jet holes, diverse combinations of jet and mainstream flow, and varied flow rates. Experimental findings conclusively demonstrate that the synergistic interaction between the jet flow and the mainstream significantly enhances the heat dissipation capacity of the jet. Taking the case of four jet nozzles as an illustration, when the aggregate flow rate reaches 150 L/min, the wall average Nu exhibits a 31 % increase compared to the scenario where only the jet flow is present. The heat dissipation capacity of an array of jets interacting with the mainstream flow is approximately six times higher than that of the mainstream alone. In the numerical simulation, the supercritical fluid flow mechanics and thermal exchange behaviors of jets under operating conditions of scramjet were thoroughly analyzed. The mutual effect between the jet and mainstream flow demonstrated a robust heat dissipation capability. Notably, the maximum Nu for the synergistic mutual effect between the jet and mainstream is seven times larger than that of the mainstream alone. In conclusion, both experimental and numerical results indicate that the heat dissipation capacity is superior under the combined action of the jet and mainstream.