| Today’s continuous development of oil fields results in increasing reservoir pressure.In order to maintain formation pressure,the amount of water injected was gradually increased.In addition,oil production from the well is declining with continuous production.These changes make the high temperature submersible pump deviate from the design condition and run at high speed.When the pump deviates from the design condition,not only the pump head,efficiency and other external characteristics will change,but also the flow field distribution and stability of the pump will change.In order to study its variation law,the high temperature submersible electric pump is taken as the research object.On the basis of the experimental analysis of its external characteristics,the Fluent software is used for numerical simulation to further study it.Considering the influence of energy loss and regional integrity of flow field on numerical simulation,three dimensional flow field is established according to four schemes for the high temperature submersible electric pump.By analyzing the energy and external characteristic parameters of the four schemes,a flow field model which can best reflect the flow field information is selected.In addition,grid independence test and grid quality evaluation were carried out under three working conditions to ensure the feasibility of numerical simulation.In the steady-state numerical simulation of high temperature submersible electric pump,firstly,the distribution law of pressure field,velocity field and streamline of impeller and guide shell as well as the whole stage flow field under five working conditions is analyzed.The complex flow phenomena of pump under different working conditions are analyzed and the working conditions and locations of cavitation are predicted.Secondly,in order to consider the influence of pressure pulsation on the stability of high temperature submersible electric pump,several monitoring points were established in each impeller and guide shell of the pump to carry out unsteady numerical simulation under design conditions.By analyzing the pressure pulsation coefficient in time domain and frequency domain,the distribution law of pressure pulsation in impeller and guide shell of each stage is obtained.The causes,locations and influencing factors of pressure pulsation are analyzed.In addition,in order to improve the overall performance of high temperature submersible electric pump,Geatpy toolbox was used to optimize the design.Considering the loss in the pump and the HPSHr performance and shaft power,the partial objective function of the impeller inlet and outlet key structural parameters and blade number was established.According to the different influence degree of the objective function,the linear weighting of each objective function is unified to optimize the design.After optimization,not only the optimal combination of impeller inlet and outlet parameters is obtained,but also the energy loss,shaft power and NPSHr are improved.Finally,the external characteristic parameters of high temperature submersible electric pump are analyzed through experiments,and the calculated results are compared with those of numerical simulation to prove the correctness of numerical simulation.The above two-stage flow field analysis and stability analysis of high temperature submersible electric pump,as well as the optimization design of impeller to improve the comprehensive performance of the pump,can provide important reference significance for the study of high temperature submersible electric pump flow field law,improve stability and improve the performance of the whole machine. |
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