Optimization of low-head shaft tubular pumping systems based on entropy production theory

In order to improve the operation efficiency of low-head tubular pump, this paper studies the influence of shaft type in the shaft tubular pump on the flow characteristics and energy characteristics of the pump. To optimize the shaft structure of shaft tubular pumping systems and realize the efficient use of energy, numerical simulation and model test was employed to study the optimization of the entire pumping system. In this paper, the CFD method was used to numerically simulate the whole pumping system, and the effect of changing the shaft length, shaft head profile, and shaft tail profile on the internal flow and entropy production characteristics of the inlet passage and impeller position were analyzed. It is found that the tapered tail profile can make the inlet passage overflow area change more smoothly and thus make the flow pattern more favorable. The wall entropy production dissipation at the inlet passage position dominates the total entropy production, and the high-value area of mainstream entropy production at this position is distributed periodically. The mainstream entropy production dissipation at the impeller section accounts for a relatively large proportion. After the entropy production dissipation analysis, it is believed that the tapered can reduce the entropy production dissipation of the pumping systems. The change of the shaft tail profile will make the entropy production dissipation change more noticeable compared with other optimization factors. Therefore, the tapered tail profile with better transition in the actual project is recommended.