Development And Research Of Compact Magnetic Pump For Special Engineering

The compact magnetic pump is small in size and light in weight.It has no leakage and no shaft seal in the transmission liquid.It is mainly used in special engineering equipment.The traditional centrifugal pump not only has large size,the shaft seal is easy to leak,but also it is not resistant to corrosion and has a short service life.It can not meet the requirements for the use of special projects.In conjunction Chinese People’s Liberation Army Force development contract.The CJRB8-70LW type of compact magnetic pump was designed and developed.Combining with the parameters of the compact magnetic pump,the hydraulic parameters of the impeller and the volute are designed,and the three-dimensional steady simulation of the full flow field including the front gap and the rear gap water is performed.Comparing the model prototype experimental data with the simulation data to verify the accuracy of the numerical simulation.Orthogonal test method is used to optimize the impeller design,and the optimal design parameters are obtained.By Changing the hydraulic dimension of the volute,and the experiments are carried out to compare the performance of the pump under different hydraulic dimensions of the volute.Unsteady calculations are performed to obtain the pressure pulsation by using the constant calculation results as initial conditions in the pump and the changes in the axial and radial forces on the impeller.Based on Workbench software,the structural static and structural dynamics of each component of the magnetic pump（impeller,pump body,isolation sleeve）are analyzed to obtain the magnetic pump force conditions and modalities,So,it could Verify the reliability of the magnetic pump design structure.The main research contents and results of this paper are as follows:1.According to the requirements of the development contract of the Chinese People’s Liberation Army,combined with the compact size,small flow,high lift and other characteristics of the compact magnetic pump,A compact magnetic pump was designed and developed,including the hydraulic and integral structure of the overflowing parts such as impeller and volute,which is innovative.2.Solid modeling was performed for the fluid area of the compact magnetic pump,such as the impeller basin and the volute basin,and the 3D model of all the fluid areas was meshed.The whole flow field of the pump of the compact magnetic pump is numerically calculated by CFD software,and the distribution rule of pressure and velocity in the pump under different working conditions is analyzed.Also,the external characteristic of the compact magnetic pump is calculated and the compact magnetic pump was tested on the special pump test-bed of Jiangsu University to verify the accuracy of the numerical simulation.3.Orthogonal test method was used to optimize the impeller design.Nine groups of impeller hydraulic models were obtained and the hydraulic performance and internal flow conditions of each group were compared.At the same time,the range analysis and factor selection of lift and efficiency are analyzed.At last,the best design parameters were obtained that Number of splitter blades Z=5,splitter blade circumferential offset angle?（28）.04?,splitter inlet diameter D_si=0.75D2,splitter deflector angle?（28）0^?and the number of splitter blades Z=5,splitter blade circumferential offset angle?（28）.04?,splitter inlet diameter D_si=0.75D2,splitter deflector angle?（28）0^?.Compared with the original model impeller,the optimized impeller has less vortices in the flow.The flow is more smooth,and the head and efficiency are improved.In the meanwhile,three kinds of hydraulic schemes of different volute were designed,and three real prototype experiments were carried out.Experiments have shown that the base diameter of the volute and the area of the 8th cross section of the volute are important factors affecting the performance of the magnetic pump.4.The unsteady flow field is calculated for the whole flow field of magnetic pump.The results show:With the increase of flow conditions,the internal pulsation coefficient of the impeller decreases gradually.The main frequency of the pressure pulsation is mainly influenced by the axial frequency in the small flow condition and the large flow condition,and the main frequency of the pressure pulsation in the large flow condition varies at different monitoring points.In the design flow conditions,the pressure pulsation cycle is the best.Under all flow conditions,the pressure pulsation in the outlet of the volute is better than that in the flow channel.Compared with small flow rate and design flow rate,pressure pulsation is more disorder under large flow condition.Under the design flow,the axial force of the impeller is the smallest and the periodicity of the axial force pulsation is the best.The radial force of the impeller decreases with the increase of the flow rate,while the flow rate increases,and the radial force of the impeller is increasingly disturbed.5.Based on the Workbench platform,the structural statics analysis of each component（impeller,pump body and isolating sleeve）of magnetic pump is carried out.The results show:the mechanical stress and mechanical deformation of the impeller,As well,the pump body and the isolation sleeve decreases with the increase of the flow rate.And the mechanical stress and mechanical deformation of each component of the magnetic pump are in accordance with the flow field of the magnetic pump.The maximum stress in the impeller region is 83.272 MPa,and the maximum stress in the pump body region is 78.66 MPa,and the equivalent total stress in the impeller and the pump body is less than the maximum stress in most regions.The maximum stress of the impeller and the pump body is less than the ultimate stress205MPa of the material 1Cr18Ni9Ti,the impeller and the pump body design meets the strength requirements.The maximum stress in the isolation sleeve area is187.5MPa,which is less than the ultimate stress 825MPa of titanium alloy TC4.The largest deformation of the thinnest area of the isolation sleeve is 0.6889mm,which is less than the gap between the isolation sleeve and the inner and outer magnetic rotors,and there will be no interference.Structural design of isolation sleeve meets requirements.6.Based on the Workbench platform,the structural dynamic analysis of each component of magnetic pump is carried out.The results show the magnitude of the natural frequency change of the first 6 modes of the magnetic pump components under prestress and without prestress is small.The natural frequency of the modal state in the pre-stressed state is increased when compared with no prestress.The natural frequencies of each mode of the magnetic pump are far away from the main frequency of the flow induced excitation,and the magnetic pump is not easy to generate resonance.For rotary parts impeller,the modal deformation is mainly concentrated at the edge of the impeller.For the stationary component pump body,the inlet of the inlet pipe is more likely to deform.The bushing position of the isolation sleeve is more prone to deformation.