In this work, supercritical $n$-decane flowing in ducts with different orientations is thoroughly investigated in terms of secondary flow, wall shear stress, and thermal acceleration. It is known that the secondary flow strength hardly plays a role in cases of flowing upward, flowing downward, or flowing horizontally at a small heat flux/mass flux. Still, an attachment point can be found at the center for cases of flowing upward and flowing downward, and this enhances the heat transfer. For a large heat flux/mass flux, thermal transport depends not only on the secondary flow strength but also on the secondary flow structure. Besides, a separation point is found at the center for flowing up/downward cases, and the more adjacent the attachment point is to the heated wall, the more serious is the thermal transport. The wall shear stress is beneficial to heat transfer but also relies on the distribution profile. Thermal acceleration can really diminish or even restrain the HTD phenomenon, but it is not the reason to cause the difference of heat transfer behavior for channels with different orientations.

在这项工作中，超临界 $n$- 在不同方向的管道中流动的癸烷在二次流、壁面剪应力和热加速度方面进行了彻底的研究。众所周知，二次流动强度在向上流动、向下流动或在较小热通量/质量通量下水平流动的情况下几乎不起作用。尽管如此，对于向上流动和向下流动的情况，可以在中心找到一个附着点，这增强了热传递。对于大的热通量/质量通量，热传递不仅取决于二次流强度，还取决于二次流结构。此外，在中心处发现了一个分离点，用于上下流动的情况，并且附着点越靠近受热壁，热传递就越严重。壁面剪应力有利于传热，但也依赖于分布剖面。热加速确实可以减少甚至抑制HTD现象，但这并不是导致不同取向通道传热行为差异的原因。