Analysis Of Hydrodynamic Characteristics And Selection Of Main Water Pump For Low Lift Pumping Station

Low lift pumping stations are widely used in flood control and drought resistance projects in plain or hilly areas.Since entering the new century,with the implementation of water diversion,water transfer and other large interbasin water transfer project,research on large and medium low lift pumping station and rise to a new height.With the gradual maturity of technology,the energy characteristics of low lift pump unit has reached an excellent level.People's attention to the stability of low lift pump unit has been gradually improved.In order to study the low lift pump system to further promote the times,in-depth research on hydrodynamic characteristics by combination of model test in this thesis by means of theoretical analysis,numerical simulation,on the part of the typical low head pump device and method of selection of main pump,the main research content and innovation includes:(1)From the six aspects of guide vane,pressure box culvert inlet flow passage,pump station reverse power generation,three dimensional transient process,main pump selection and axial flow pump rotor's vibration characteristics,this thesis summarizes and analyzes the research status of hydrodynamic characteristics and selection of main pump type of low lift pump.With the use of CFX CEL language function such as the axial velocity distribution uniformity and efficiency of the hydraulic parameters and processing parameters for pressure signal and using Visual Basic6.0 to write for two times the development of Excel program,providing tools support for the follow-up study.The different turbulent models were applied to the numerical calculation of the whole flow field for hydraulic characteristics of the reverse generating pump,and the results of the calculation were compared with the values of the model test to the prototype,and a turbulence model suitable for the two working conditions of the pump and the turbine was obtained.The effects of the different tip clearance on the characteristics of the water pump and water turbine under two operating conditions are calculated and analyzed.The blade tip clearance will have a significant influence on the hydraulic characteristics of the water pump and water turbine,but the hydraulic characteristics are sensitive to the size of the tip clearance,and the clearance of the blade tip is required consideration for the numerical calculation.(2)Numerical calculation method of UDF and dynamic grid is used to study the three-dimensional transition process of the pump device with reverse power generation.The influence of the combination of fast door and small beat door and simple fast gate on the hydrodynamic characteristics of the pump device in the process of starting process is revealed for the first time.When the operation condition of the pump unit is converted from the rated working condition of the pump to the rated condition of the turbine,the total process of the pump unit needs three processes,namely,the pump condition,the braking condition and the hydraulic turbine working condition.Pump power fast gate refusing the transition process,changes with time is characteristic of unit,unit for about 25s or about to lift the runaway speed in the highest lift power,and the results were compared with the numerical simulation of the conversion to the prototype of runaway speed value,pressure pulsation amplitude unit in the transient process of runner outlet monitoring over time increases rapidly.Water hammer will appear in the flow channel when the pump and water turbine are converted.(3)Through the theoretical calculation,we get the profile equation of the pressurized box culvert inlet channel.We use Visual Basic6.0 to develop Auto CAD2008 two times,and compile a set of parameter runner design program based on the pressure box culvert inlet line equation control parameter.The influence of the control parameters of different inlet channel lines on the inlet channel objective function is calculated and analyzed.Study on the hydrodynamic characteristics and the runaway transition process of super low head two-way vertical pump device of CFX numerical simulation and model test method based on the combination of two-way vertical axial flow pump device is not in the vicinity of the transition process in the water cone and runaway due to low-frequency pressure pulsation caused by the vortex in the draft tube,the numerical CFX simulated runaway speed values are in good agreement with the model test conversion value.(4)Based on the study of the hydrodynamic characteristics of the tubular pump in the front shaft.It is the fist time to discovery that when the guide vane body is removed,the pump outlet flow in front of the shaft through appears consistent with the draft tube vortex characteristics,the vortex of the water flow in the outlet,will cause the low-frequency pressure pulsation frequency.(5)Based on the research method by CFX numerical simulation,the matching between the runner and the guide blade of the different axial flow pump is calculated and analyzed.The runner has a decisive influence on the hydraulic performance of the axial flow pump section,and the high efficiency zone of the hydraulic model can be adjusted by replacing the guide vane.The hydraulic model of two axial flow pump with similar hydraulic performance has no obvious effect on the hydraulic performance of the pump section after exchanging the guide blade.(6)Based on the research method by ANSYS ACT numerical simulation,the vibration characteristics of axial flow pump rotor under different working conditions are thoroughly studied.The results show that the effect of flow force on impeller is not obvious,and the water body wrapped outside the impeller has a significant effect on the vibration characteristics of the impeller.Under different operation conditions,the natural frequency of the axial pump rotor is much lower than that of the pump runner blade,and the possibility of resonance is very small in practical operation.(7)Through the research and analysis of the selection method of the main water pump in the traditional low lift pump station,a new selection method is put forward for the first time.Based on the technology developed by Visual Basic6.0 for the two development of Auto CAD2008,a set of selection procedures for main pump of low lift pump station has been compiled,and it has been successfully applied to the selection of main pumps of several large pumping stations,and achieved good engineering results.