Thermal behavior of supercritical CO2 inside scramjet cooling channels with different structural parameters

• Published in: Applied thermal engineering Vol. 217
• Main Authors: Zhou, Xingyu, Zuo, Jingying, Li, Xin, Zhang, Silong, Qin, Jiang, Bao, Wen
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 25.11.2022
• Subjects: Cooling channel; Scramjet; Supercritical CO2; Thermal behavior; Cooling channel; Supercritical CO2; Scramjet; Thermal behavior
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2022.119153

The supercritical CO2 closed Brayton cycle is a promising cooling scheme for hypersonic aircraft. However, the high pressure and large heat flux make the thermal behavior of supercritical CO2 inside the cooling channel extremely complex. In this study, the turbulent heat transfer of supercritical CO2 in different structural cooling channels is simulated by using the modified turbulence model. A mathematical model of heat transfer coefficient is established by theoretical derivation. The model shows that the heat transfer coefficient is determined by 6 parameters such as turbulent viscosity (μtδ) and wall viscous shear stress (τw). The study found that there is still a slight local heat transfer deterioration (HTD) at low aspect ratio, even though the CO2 is far from the critical state. By weight analysis of the mathematical model, the results show that the μtδ and the τw have the greatest influence on the heat transfer coefficient at the low aspect ratio, and their local decay causes the local HTD. With the change of aspect ratio, the bottom heat load and the μtδ have the opposite rule, which makes the cooling channel have an optimal aspect ratio and its value is about 0.8. •The optimal aspect ratio of the supercritical CO2 cooling channel is around 0.8.•The heat transfer coefficient is determined by 6 parameters such as μt and τw.•The local attenuation of μt and τw causes local heat transfer deterioration.