Author(s): S. Abdel-Fattah
Linked Author(s): M.B.A. Saad
Keywords: Vortex formation; Pump intakes; Physical model; Exaggerationdischarges; Curtain walls
Abstract: A new land reclamation project is under construction in south of Egypt. This project includes a big pumping station consists of 24 units of pumps. Since vortices formed in pump sumps may increase the head loss and vibration rate, decrease pump efficiency, and cause erosion in pump blades due to air entering. The vortex formation in front of the pump intakes, under different operation conditions, was investigated using an undistorted physical model. The model was constructed at the Hydraulics Research Institute, Delta Barrage, Egypt. As the physical model was operated with the similarity of Froude law, scale effects due to viscosity and surface tension forces were investigated. The results of these investigations assured that, the construction of the intake model with scale of 1:10 satisfied the limits of both the Reynolds and Weber Numbers. Consideration of similarity aspects revealed that, for the analysis of vortex formation the Weber-Number is the relevant parameter. Accordingly, exaggeration of pump discharge was applied to achieve Weber numbers in the model to be close to that one in the prototype. The pump discharge was varied by an exaggeration factor in a range from 1.5 to 2.8. The highest intensity to vortex formation was obtained with an exaggeration factor of 1.5. Measured velocities in the immediate upstream vicinity of pump intakes proved to be unaffected by the flow conditions further away in the suction basin. The inflow velocity distribution at the pump intakes is rather uniform. Local inflow velocities showed a maximum deviation of15% from the average. To minimize vortex formation, several arrangements of curtain walls at the pump intakes were investigated. The hydraulic model tests clearly showed that the arrangement of curtain walls suppresses vortex formation effectively.
Year: 2001