Numerical Simulation of the Internal Flow of a New-Type Shaft Tubular Pumping System

The structural features of a pumping system will directly affect the investment of the pumping station and its pumping efficiency. In the design and construction of low head or extra-low head pumping stations, bulb tubular pumping system and shaft tubular pumping system are widely adopted. So far all the 5 large tubular pumping stations finished or under construction took the form of rear type bulb tubular pumping system (bulb is arranged inside the discharge passage) in China’s Eastern Route Project of South-to-North Water Diversion. However, front type shaft tubular pumping systems (shaft is arranged inside the suction box) are more widely used in city flood-control pumping stations, which are characteristic of large amounts and medium or small scale. To improve the reliability of city flood-control pumping stations, the authors have invented a new-type shaft tubular pumping system featuring shaft suction box, siphon-type discharge passage with vacuum breaker valve as the cutoff device, which is possessed of such advantages as simpler structure, reliable cutoff and better energy performance. Taking an real pumping station in Yancheng city of China as an example, the computational fluid dynamics method was adopted in this paper to simulate the three dimensional turbulent flow of a model new-type tubular pumping system (impeller diameter D = 0.3m, rotational speed n = 1100r/min and specific speed ns is about 1500) and predict its performance, to improve the pumping system efficiency through hydraulic design optimization. Computation results show that the efficiency of the new-type shaft tubular pumping system reached 56.0% when the design head and discharge are 1.15m and 0.326m³/s respectively, and up to 68.8% when the maximum head and relevant discharge are 1.95m and 0.296m³/s respectively, having more extensive foreground for low-head, especially extra-low-head city flood-control pumping stations.