| As an important part of water conservancy facilities,pumping station is not only indispensable in urban water supply and water transfer,but also an important building for water supply and drainage in agriculture.Low-lift drainage pumping stations are widely used in plain areas of China which have made important contributions to flood control and drainage.With the deepening of the research on the pumping station in recent years,the pump unit is an important part of the low lift drainage pumping station and the hydraulic performance of the pump unit directly affects the operation efficiency and safety and stability of pumping station.Jiangou Pumping Station is a sub-project of the adjustment and reconstruction project of the flood discharge area from Zhengyangguan to Xiashankou in the main stream of Huaihe River which is a vertical axial flow drainage pumping station.The inlet and outlet flow are undertook by elbow flow channel and volute flow channel respectively.The design drainage flow of pumping station is 41.9m/s.In this paper,according to the actual situation of Jiangou pump station,the appropriate pump model was selected through comparison and selection and the hydraulic performance of the pump unit was studied by numerical simulation and model test.The main research contents and conclusions of this paper are as follows:(1)Based on the design parameters of Jiangou pumping station,the pump selection was carried out by the selection coefficient method.Through the comparison of performance curves,TJ04-ZL-19 has excellent cavitation performance and high operating efficiency under the design head,compared with TJ04-ZL-06,TJ04-ZL-19 and TJ04-ZL-20.Therefore,TJ04-ZL-19 was finally selected as the pump model of Jiangou pumping station.(2)Through numerical simulation of the inlet channel of Jiangou pumping station and the comparison of different schemes,it can be found that the hydraulic performance of the elbow inlet channel optimization scheme was improved compared with the original scheme.Due to the structural requirements of the pumping station,the middle pier in the inlet channel needs to be retained.Therefore,the elbow flow channel optimization scheme 1 is selected,in which case the head loss is 0.152 m,the average angle of the water inflow pump is 88.6° and the uniformity of the velocity distribution is 98.1%.(3)In the numerical simulation of the outlet channel,it can be found that the low hump outlet channel optimization scheme was superior to the volute outlet channel optimization scheme in terms of head loss.However,considering that Jiangou pumping station is a low-lift drainage pumping station,its stable operation requirements should be guaranteed.The high elevation of the hump section of the low hump outlet channel will affect the structure of the pump house and may accumulate gas in the hump at the lowest water level of the outlet pool,which may cause unstable operation of the unit.Since the channel type line of volute outlet channel is relatively simple,it can reduce the height of the flow channel and meet the requirements of the existing pump house structure layout,so that the project investment is low and its maintenance and installation also has obvious advantages in which case the head loss of the scheme is 0.564 m and the water flow spreads smoothly.The pump unit model was constructed by comprehensively comparing the selected elbow inlet channel and volute outlet channel.Through numerical simulation of the pump unit,the efficiency of the pump unit is 71.5%under the design condition.(4)The external characteristic performance of the pump unit of Jiangou pumping station was studied by model test and the test results show that the highest efficiency point of the pump unit appears when the blade angle is-2°.When the pump unit runs under the design head and the highest head interval,the device efficiency can maintain a high efficiency operation and the device efficiency fluctuates little with the head alteration.It can be ensured that the Jiangou pumping station as a drainage pumping station can still maintain operation with high efficiency when the water level changes.Additionally,the critical cavitation allowance at all angles under the design head was less than 9.91 m,less than 8.70 m under the maximum head which means that the cavitation damage will not be caused.Hence,Jiangou pump station has good runaway characteristics and stable state of pump unit when the blade installation angle is-2°.The research results of this paper can provide some reference for the application and development of volute flow channel,bringing some experience and ideas for the experimental research of low lift vertical axial flow pump unit. |
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