Research On The Hydraulic Performance And Pressure Pulsation Of Submersible Tubular Pumping System

The submersible tubular pump is the mechanical and electrical integration of the submersible motor and the axial flow pump.The structure is very compact,the light bulb is small and the light weight not only reduces the pressure of the support but also is beneficial to the flow over a body.At the same time,the pump also has good noise resistance property which solves the technical problems of the heat dissipation,insulation,sealing and automatic drainage of the motor in the process of development.It is a new type of pump type suitable for large flow,low lift irrigation or drainage pumping station.The pump station equipped with submersible pump has low construction and operation cost,high efficiency,easy to automatic or semi-automatic control.With the development of the national economy and the implementation of the national water diversion projects,the submersible pump station plays a more and more important role in the development of the national economy.Especially in recent years,the change of climate causes the uneven distribution of precipitation,which gives a great test to the safety and reliability of such pumping stations.It is of great social and practical significance to discuss the stable operation range of the submersible tubular pump,reveal the unsteady three-dimensional flow phenomenon and ensure the safe and stable operation of the submersible turbine pump station.At present,the research on steady flow characteristics of the submersible tubular pump is relatively mature at home and abroad.The numerical simulation is the main research of the pressure pulsation under unsteady flow.Based on a submersible tubular pump station,this article is to study the flow characteristics and pressure pulsation characteristics of a submersible tubular pump with two methods---numerical simulation and model test.The performance curve of the submersible pump under the rated speed was obtained by the test of the characteristic of the submersible pump,and the high efficiency area of the pump was determined to be 16L/s-22L/s.With the help of CFD,the numerical calculation of the constant flow path of submersible pump were calculated,performance curves calculated from model test and numerical simulation are coincide in high efficiency operation of pump unit,different in deviation from design conditions.However,the overall numerical simulation results are accurate.Through numerical simulation,the detailed internal flow field results are obtained under three characteristic conditions,and the changes in the characteristics of the pump unit under the three working conditions are analyzed.By using the high frequency pressure sensor on the impeller outlet,the pressure fluctuation signal of vane outlet and pump axial wall were collected,with the help of Origin and other data processing software,time domain and frequency domain distribution of comparative analysis under different working conditions and different monitoring points are compared.The main frequency of pressure pulsation of the 3 monitoring points in the circumferential direction of the impeller outlet section is basically the same,and the maximum amplitude is obtained at the blade frequency,but the difference of the amplitude is larger.;with more frequency interference,the pressure fluctuation components of guide vane outlet are more complex,the main frequency of the four monitoring points is basically the same in addition to the monitoring point P4,the maximum amplitude of the other 3 monitoring points is very close.The main frequency of each monitoring point is basically the same,and the maximum amplitude is achieved at 3 times of the frequency.Besides,with the farther distance from the monitoring point to the impeller,the 3 times shift frequency amplitude is getting smaller.The pressure pulsation characteristic at the outlet of impeller is most obvious with the change of flow rate.The pressure pulsation of guide vane,outlet outlet and bulb section is less influenced by flow rate.The low flow condition is easy to produce cavitation,and the high frequency components are more.The full unsteady number of submersible through flow pump device was calculated using CFD technology,and the pressure pulsation frequency diagram was obtained,which shows high degree of agreement with the results of model test,especially the monitoring points of the impeller and the guide vanes on the wall surface,whose frequency and amplitude are relatively close to but slightly deviate in the amplitude of the wall of the bulb.At the same time,the distribution of pressure fluctuation for total of 7 feature bulb tail sectiont---the impeller inlet,impeller outlet,guide vane,vane outlet,intermediate bulb,bulb intermediate transition section---are obtained.Besides,the flow characteristics and the turbulent kinetic energy change of inside impeller,guide vanes and internal bulb.