Numerical simulation of optimal bulb of tubular pump
Zhou Jiren1,2, Cheng Li2, Liu Chao2, Tang Fangping2
(1.College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, Jiangsu 210098, China; 2.College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou, Jiangsu 225009, China）
Abstract：The flow patterns and hydraulic performances of two different bulbs of pump system, i.e. normal type and slin type, were studied. Based on the RNG k-ε model, the SIMPLEC algorithm was applied to the solution of the discretization governing equation. Using multiple reference frames, the flow details of whole pumping systems whose length was of 10.72D, where D was of the impeller diameter, were obtained. The influences of the flow of pump system on difference bulbs were analyzed.The unsuitable design of bulbs caused flow separation and vortex. The calculation results illustrate that the static pressure contours of two pumping systems which were operated at design flowrate, large flowrate and small flowrate, were similar, and therefore the shape of bulb does not impact on the operation status of impllers. The results showed that the flowrate of minimum loss for slin taper bulb is of 112 percent of design flowrate, while that for normal bulb is of 106 percent of design flowrate. It is not quadratic function between flowrate and hydraulic loss, and the loss is somewhat related with the operating region. 3D numerical computation and model test showed that the performance of slin taper bulb was better than that of normal one, and consequently this type of pump system can be applied in the East Route Project of South-to-North Water Transfers.
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