Flow pattern analysis on inlet and outlet conduit of shaft tubular pump system of Pizhou pumping station in South-to-North Water Diversion Project

In order to reveal the relationship between the internal characteristics and external characteristics of shaft tubular pump system and to perfect its theory of the optimum hydraulic design, flow patterns of the conduit surface and the sections perpendicular to x, y, z directions for shaft tubular pump system of Pizhou pumping station in Eastern Route of South-to-North Water Diversion Project were analyzed in detail from all angles of view by 3D turbulent numerical simulation. And the numerical simulation results of the flow pattern were verified by both transparent conduit model test and transparent pump system model test. The results of numerical computation and model test came to the conclusions as follows: 1) Flow pattern was uniform and smooth in the inlet conduit of the pump system, and the stream line layers were clear; 2) Flow in the outlet conduit diffused gently in the form of spiral motion, and there was no improper flow such as separation or vortex in the conduit; 3) The main reason of the excellent hydraulic performance of the pump system was due to the excellent internal characteristics. At the main operation points of the pump system, the pump system efficiency exceeded 83%, critical cavitation flow margin was lower than 5m and the hydraulic performance of the pump system was excellent. The research results provide a beneficial reference for the hydraulic design of pumping stations with low head.