In this paper, we consider the flow and heat transfer behaviour of turbulent upward and downward flows of supercritical n-decane, in order to reveal the features of heat transfer deterioration (HTD) that would be expected in relevant active regenerative cooling systems for scramjet engines. Specific focus is placed on key velocity-field features that appear in these flows. Following the validation of six turbulence models, the SST k-ω and RNG k-ϵ models are found to be suitable for simulating the upward and downward flow cases, respectively. “M” type velocity profiles (a non-monotonicity of the velocity along the radial direction) are observed, which arise due to a spatially-varying interplay between the inertial and viscous forces in the flow domain, while larger velocity gradients in the buffer layer are also observed that contribute to the phenomenon of HTD. Furthermore, it is found that the secondary flows as well as the different mass fluxes that arise due to the velocity increase from the wall to the flow core zone (i.e., the influencing range and intensity of cross-sectional kinetic energy), respectively, are observed in the HTD development region, as well as the HTD peak area and degradation regions. A zone of higher thermal diffusion appears in the near-wall region, which acts as a thermal barrier and contributes to HTD.

在本文中，我们考虑了超临界正癸烷湍流向上和向下流动的流动和传热行为，以揭示超燃冲压发动机相关主动再生冷却系统中预期的传热劣化（HTD）特征。 . 特别关注出现在这些流动中的关键速度场特征。在六个湍流模型的验证之后，SST k - ω和 RNG k - ϵ发现模型分别适用于模拟向上和向下流动的情况。观察到“M”型速度剖面（沿径向速度的非单调性），这是由于流域中惯性力和粘性力之间空间变化的相互作用而产生的，而缓冲层中的速度梯度较大也观察到有助于HTD现象。此外，发现二次流动以及由于从壁面到流动核心区的速度增加而产生的不同质量通量（即横截面动能的影响范围和强度）分别为在 HTD 发展区域以及 HTD 峰面积和降解区域中观察到。在近壁区域出现较高的热扩散区，