Study On Hydraulic Optimization Design Of Open Type Low Head Large Pump

Open low-lift large pump device is widely used in urban flood control and waterlogging engineering, water supply and irrigation and drainage engineering for its advantages of simple structure, easy installation and maintenance and so on, but the research on hydraulic optimization design is not comprehensive enough, and still cannot meet the requirements of the engineering. Therefore, this paper systematically studies on the hydraulic optimization design of open type low-lift large pump station.Firstly this paper uses ANSYS CFX, STAR-CCM+ and other software to carry out an univariate and multivariate orthogonal study on numerical simulation of bell-type suction tube and tank outlet passage, on the basis of the hydraulic optimization design of inlet and outlet passages, in combination with large open pumping stations-Fu’an pumping station in Jiangsu Province, assemble the optimized inlet and outlet passages with pump model into a pumping station and study the performance of Fu’an pumping station using the methods of CFD and model of the pump device experiment. The specific research topic includes:(1) This paper designs an orthogonal experimental plan with the orthogonal array L16(45) including 5 factors (the trumpet heightH1, the clearance between trumpet and floorH2, bell suction diameterD1, hygroscopic box heightH3, passage widthB) and 4 levels for the bell inlet conduit. Taking the hydraulic loss of inlet conduit, the uniformity of speed of inlet conduit and inflow angle as the goal function, we use the method of extreme difference analysis to determine the important order of 5 factors and obtain the optimal combination of scheme. We study on the influence law of the hydraulic loss of inlet conduit, axial velocity distribution of inlet conduit and inflow angle affected by different levels under the same factor and compare the internal flow field of different schemes.(2) Based on the results of orthogonal test study,24 schemes of numerical experiment for the trumpet height and the clearance between trumpet and floor was designed to study on the influence law of the hydraulic loss of inlet conduit, the uniformity of speed of inlet conduit and inflow angle affected by the variation of trumpet height and the clearance between trumpet and floor systematically, and do a comparative analysis of the internal flow field of different schemes.(3) Based on the systematical research of bell-type suction tube, in combination with large open pumping stations-Fu’an pumping station in Jiangsu Province, we study on the influence law of the hydraulic loss of inlet conduit, the uniformity of speed of inlet conduit and inflow angle affected by 5 different types of the clearance between trumpet and floor, and do a comparative analysis of the internal flow field of different schemes.(4) Taking tank outlet passage as the research object, taking the hydraulic loss of outlet passage as the objective function,15 schemes of numerical experiment were desgined including 5 different outlet passage heights and 3 different clearances between top plate and flare pipe tube and the numerical experiment was conducted under 3 different mass flow to research on the hydraulic optimization design of tank outlet passage.(5) Based on the research of the hydraulic optimization design about the conduit of open type pump device, we design the bell-type suction tube and tank outlet passage for Fu’an pumping station, make the model of pump device to test the energy characteristics of the model of pump device under different blade angles.(6) Taking the model of pump device of Fu’an pumping station in Jiangsu Province as research object, we use the method of CFD to study on the model of pump device, and do a comparative analysis of the results between numerical modeling and model experiment.It comes to the conclusion based on through the research of numerical modeling and model experiment:(1) The research of orthogonal experiment indicates that the diameter of suction bell-type plays a key role in affecting the hydraulic performance, with the increment of the suction bell diameter, the axial velocity distribution increases, the hydraulic loss decreases, and also the inflow angle increases at first and then decreases later.(2) The multilevel experimental research of the trumpet height and the clearance between trumpet and floor indicates that, with the increment of the clearance between trumpet and floor, the axial velocity distribution increases, meanwhile, the hydraulic loss has a downside, the hydraulic loss decreases rapidly at first and then slowly increases later with the increment of trumpet height while the clearance between trumpet and floor is fixed, and there is a minimal value appearing in the zone nearby 0.3 D0, the axial velocity distribution has a upward trend but become slow after 0.4D0 with the increment of trumpet height while the clearance between trumpet and floor is fixed, the inflow angle increases at first and then decreases later with the increment of trumpet height while the clearance between trumpet and floor is fixed and the trumpet height is bigger than 0ADo, and there is a maximal value appearing in the zone nearby 0.4D0.(3) The multilevel experimental research of the clearance between trumpet and floor when the height of bell-type suction tube is fixed indicates that, the axial velocity distribution increases with the increment of the clearance between trumpet and floor, then changed to be steady after 0.5D0 when the passage height is fixed, the inflow angle decreases at first and then increases with the increment of the clearance between trumpet and floor while the passage height is fixed, and there is a minimal value appearing between the area of (0.6-0.7)D0, the hydraulic loss decreases at first and then changed to be steady with the increment of the clearance between trumpet and floor while the passage height is fixed.(4) The multilevel experimental research of passage height and clearance between top plate and flare pipe tube indicates that, the hydraulic loss increases as the passage height increases, the law that the passage height and clearance between top plate and flare pipe tube influence the hydraulic loss is the same in 0.8 to 1.2 times the design flow range, it is significant to reduce the hydraulic loss with a little improvement of the passage height while the height of the clearance between top plate and flare pipe tube is fixed, the hydraulic loss increases as the clearance between top plate and flare pipe tube increases while the passage height is fixed, the variation of the passage height has a little influence on the hydraulic loss while the clearance between top plate and flare pipe tube is 0.4D0.(5) The hydraulic performance of the pump system composed of inlet, outlet passages which are optimized design and the model pump which is supported by water pump supplier is good, the pump system runs steadily, and there is no conspicuous vortex, vortex band, abnormal vibration and noise in the inlet passage in the process of testing. The flow of the model pump device is 338L/s under the design net head with the blade angle is +2°, converted into the prototype of pump parameter by standard formula is 11.5m3/s which is close to design flow11.8m3/s.(6) The numerical simulation research on the model pump device of Fu’an pumping station indicates that the trend that head declines as the flow increases agrees with the result gathered by experiment. The results of numerical simulation are mainly identical to the results gathered by experiment in the design condition interval while there is a significant error deviated from design condition.