Analysis On The Flow Characteristics Of Postpositional Bulb Tubular Pumps

For large discharge and low lift head, it is especially suitable to use tubular pumps for their economic characteristics. Tubular pumps have high pumping devices efficiency, small hydraulic loss, strong discharge capacity, compact units structure, simple construction arrangement and low cost both for construction and running. Now in the east route of South to North Water Diversion Project, many pump stations choose tubular pumping devices. It is important to analyze the flow characteristics and pump performance of tubular pumping devices for it will be very useful for practical engineering.Based on the Reynolds-Averaged N-S equation and RNG k-εturbulent model, this paper simulates the inner 3D turbulent flow field of postpositional bulb tubular pumps. The inlet and outlet conduits are modeled and plotted into structured grids with ICEM CFD. And the impeller and diffuser are modeled and plotted into structured grids with TurboGrid. CFX is used to make a full study on the inner flow field and pump performance.The calculated results of the flow field indicates that the numerical simulation technique is feasible. With calculated results, the distributing of velocity and pressure inside the postpositional bulb tubular pump, especially for the parts of diffuser and outlet conduit's bulb section, is obtained. Together with the calculation for each part's hydraulic loss, we know that in the parts of diffuser and outlet conduit's bulb section there is much dropping flow and the most hydraulic loss that varies most with the flow. This paper analyzes how the size of pump barrel and bulb affects the efficiency. It indicates that in bigger pump barrel, there is smaller velocity and it leads to higher efficiency. But the size of bulb can't be too big for it lows the efficiency. All these achieved are the guides to improve the performance of postpositional bulb tubular pumps.