| Our national territorial area is large. Rainfall distribution is uneven in time and space. Large pumping station projects play an important role in ensuring agricultural production and living water and drainage in low-lying area. Vertical mix-flow pumping station had a lot of advantages in mature technology, equipment maintenance, working environment of motor, wide high efficiency range. It is widely used in inter-basin water transfer project, irrigation and drainage and water storage project. According to large vertical mix-flow pumping station,numerical simulation and model test are applied in hydraulic optimization design of elbow inlet passage and analysis of transient state. The main contents of the research are as follows:1.Combined with practical engineering drawing, four control variables were used to design the elbow-inlet passage such as length, the radius of circle of passage bending section and floor tilt angle for the first time. Orthogonal table and CFD numerical simulation were used to compare the performance in different plans of profile lines and select the best.2.Matching inlet passage, pump and outlet pipe, the whole flow passage was simulated. The difference of flow field was analyzed in different flow rate. The synthetic characteristic curve of pump device was described by drawing. The results of simulation were close to test.3.Based on the characteristics method and Flowmaster software, network model of pump device system was established. Under the worst condition, the transition process of launch of pump set was simulated. The variation of main parameters was analyzed such as speed, flow rate, power and water-hummer pressure. The open law of butterfly valve was designed in the launch process of set to avoid the overlord and excessive water-hummer pressure and reverse flow rate. The approach of Safe launch of pump was supplied.4.Based on the characteristics method and Flowmaster software, The transient process of emergency shutdown was simulated in different conditions. The variation of parameters was analyzed such as speed, flow rate, power and pressure. The max back flow rate and revolving speed were calculated and the results could be regarded as reference for strength checking of pump.When pump was normal shutdown, the transients of pump set was simulated in the highest head. In consideration of the max reverse revolving speed, flow rate and water-hummer pressure, the program of two-phrase close of valve was optimized. The normal shutdown of pump set would be security and reliable.5. According to the discharging tube was too long and upward slope was big in mix-flow pump set model. The model could not be installed completely on test-bed. A new method of change the slope direction and bend position was suggested. The hydraulic loss of modified tube could be equal to the original.This way could be referenced in similar pump station.6. Optimized elbow-inlet passage and matching pump model composed pump assembly model. On high precision enclosed test bed, pump assembly model test was tested including energy characteristics, cavitation performance, pressure fluctuation, runaway characteristics and hydraulic loss of passage. The results show that: the hydraulic performance of inlet passage was fine and the efficiency of pump assembly was high. When the pump station operate in designed condition, the highest efficiency of device could reach 82.97%.Cavitation performance was fine and pressure fluctuation was weak. The test could offer suggestion for parallel pump station in optimization design and operationIn this paper, the hydraulic optimization of elbow-inlet passage and transient process in large-scale vertical mix-flow pump station were studied and acquire series of outcomes. The outcomes have been applied to engineering and given protection for high efficient and steady operation of pump station. |
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