In axial flow pump systems, not only are the flow rates typically large but the water leaving the guide vanes almost invariably possesses a residual rotation. Since such pumps often generate only low heads, the energy content of this residual rotation often has a notable influence on the hydraulic and economic performance of the outlet conduit. The hydraulic losses and flow fields associated with a specific siphon outlet conduit under different rotational speeds are herein studied both experimentally and using a 3D turbulent flow numerical simulation. In order to experimentally verify the simulation results, the hydraulic losses are measured and flow patterns are observed for a siphon outlet conduit with a series of different guide vanes. It is observed that as the rotational speed increases the hydraulic loss within this outlet conduit increases gradually until the rotation speed reaches 300 $\text{r mi}{\text{n}}^{-\text{1}}$; as the rotational speed surpasses this value, the hydraulic losses increase sharply. Yet surprisingly, residual swirl can have benefits, with the general trend being that larger rotational speeds are associated with a smaller vortex zones and a better flow field in the outlet conduit, an observation confirmed both numerically and experimentally. This research has considerable significance, both theoretically and practically, for the design of outlet conduits and guide vanes in axial flow pump system.

在轴流泵系统中，不仅流速通常很大，而且离开导叶的水几乎总是具有残余旋转。由于此类泵通常仅产生低扬程，因此这种剩余旋转的能量含量通常对出口管道的液压和经济性能具有显着影响。本文通过实验和使用 3D 湍流数值模拟研究了在不同转速下与特定虹吸管出口管道相关的水力损失和流场。为了通过实验验证模拟结果，测量了具有一系列不同导向叶片的虹吸出口管道的水力损失并观察了流动模式。$\text{米}{\text{n}}^{-\text{1}}$; 当转速超过该值时，液压损失急剧增加。然而令人惊讶的是，残余涡流可以带来好处，总体趋势是较大的旋转速度与较小的涡流区和出口管道中更好的流场相关联，这一观察结果在数值和实验上都得到了证实。该研究对轴流泵系统出口管道和导叶的设计具有重要的理论和实践意义。