Numerical investigation of vortex formation in water intake system of a pumping station during low and high tides

摘要

The performance of pumps installed in pumping stations depends greatly on vortex formation at pipe intakes. Usingnumerical simulations and experimental methods, this study focuses on vortex formation in water intake system of apumping station under the tidal conditions of the Bahmanshir River. The intake system consisted of a suction pipe anda fine intake screen. Realizable k–ε turbulence model together with volume of fluid (VOF) two-phase (water–air) modelare used to simulate the flow field in the water intake system. Vortex formation, flow pattern and flow uniformity areinvestigated. Water levels and free surface velocities of the river are measured in a 1-year period. The water levels rangefrom 2.1 to 4.9 m and the corresponding free surface velocity varies from 1.05 to 2.35 m/s. The numerical results showthat two wall-attached vortices permanently stretched to the intake screen. Additionally, two symmetrical vortices withdifferent intensities formed in the intake screen. As the submergence of the intake pipe decreases during low tides,stronger vortices arise in the screen. Analysis of the velocity uniformity shows low level of flow uniformity at the pumpintake. Low level of uniformity is attributed to the existence of the intake screen and its check valve, which facilitates theformation of vortices in the suction pipe. Based on present analysis, recommendations for modifications and improvementsto the design of the pumping station are presented.