Numerical Simulation And Multi-Field Coupling Researches On Transmission Characteristics Of Magnetic Coupling Of Magnetic Pump

As the core component of magnetic pump,magnetic coupling is widely used in various industries because of its non-contact torque transmission mode and static sealing structure,which solves the problem of medium leakage when magnetic pump works.Because of the deficiencies in the current research of magnetic drive,a pair of cylindrical magnetic coupling is improved and designed which is based on the existing high-speed‘wet'magnetic drive test-bed,and the following four aspects are studied:magnetic field intensity distribution,magnetic torque and magnetic eddy loss calculation,transmission performance influencing factors analysis and magnetic-thermal-fluid-solid multi-field coupling analysis.?1?Based on the theory of Maxwell's electromagnetic field and the principle of superposition of magnetic field,the mathematical analytical model of cylindrical magnetic coupling is constructed,and the analytical formulas of the intensity distribution in magnetic field of the magnetic steel and air gap regions are deduced theoretically,which can provide reference for the calculation of the intensity in the magnetic field of cylindrical magnetic coupling.?2?According to the empirical formula,the magnetic torque and the magnetic eddy loss of the design model are calculated in different ways.It is concluded that the maximum magnetic torque and the magnetic eddy loss at 5000 r/min are:_maxEx=91.63 N?m?_Ex=3.927 kW.Maxwell software is used to analyze the transient magnetic field of 2D and 3D models,respectively.The conclusion is that:?a?.In a whole period of motion?45°?,the resultant force between magnetic torque and clearance varies sinusoidal with the magnetic rotation angle,and the trend is consistent,reaching the peak at 11.25°and 33.75°,respectively;And the magnetic density between magnetic eddy loss and clearance varies periodically with the difference of magnetic rotation angle,reaching the peak at 22.5°.Within the range of parameters,it is found that the resultant force between magnetic torques and clearances,the distribution of magnetic eddy loss and magnetic density between clearances vary with the variation of magnetic rotation angle with the periodic value of 2?/p?p is the magnetic poles?and 4?/p,respectively.?b?.The results of maximum magnetic torque and eddy loss obtained by three methods are as follows:_maxEx>_max2D>_max3D?_Ex>_2D>_3D.Through comparative analysis,it can be seen that the results of 3D magnetic field calculation are body torque and magnetic eddy loss.The leakage effect at the end of the model is fully considered.Therefore,the 3D numerical simulation method is selected for follow-up research.?3?The influence of the change of magnetic steel structure on the transmission performance of magnetic coupling is studied by using magnetic torque and magnetic eddy loss as evaluation indexes.The results show that:?a?.The increase of magnetic pole logarithm has a simultaneous effect on magnetic torque and magnetic eddy loss,and both of them tend to increase first,then decrease,and finally stabilize.In order to facilitate the selection of magnetic pole logarithm,parameters of the model were optimized by introducing the utilization ratio of magnetic steel material.The model reached the optimum value of magnetic torque and magnetic eddy loss in 16pairs.?b?.Rotational speed mainly affects the magnetic eddy loss,and the relationship between the magnetic eddy loss and rotational speed is9)9)²₄4))/9)9)²₄4)+1).Rotational speed has little effect on the magnetic torque while the magnetic torque decreases by about 0.5%with the increases of rotational speed by 1000 r/min.?c?.The influence of working temperature on transmission performance is mostly caused by changing the permeability of magnetic steel.Compared with the transmission performance of magnet steel at 20?the magnetic torque decreases by about2%at 60?and 35%at 150?.?d?.Increasing the gap between magnets will lead to a small reduction in magnetic torque and eddy loss.However,when matrix?A3 steel?is added between the clearances,the magnetic torque decreases slightly,but the magnetic eddy loss increases by about 1.2 times.?e?.Increasing the inclination angle of the magnet will result in the decrease of the magnetic torque and the magnetic eddy loss slightly.The maximum magnetic torque decreases by 0.68N?m and the magnetic eddy loss decreases by about 10 W when the inclination angle increases by 2°.However,the increase of the inclination angle of the magnet will make the fluctuation of the magnetic force more uniform.For this model,the tilt angle of the magnet is the smallest in the time gap of 6°??/4p?.?f?.The influence of the number of magnet grades on the transmission performance is mostly related to the magnetizing method chosen by the magnet.When the same magnetizing mode is applied to the axial magnets,the number of stages has no effect on the magnetic torque and the magnetic eddy loss.When the staggered magnetization mode is used,the magnetic torque and eddy loss will be greatly reduced,and the low intensity in magnetic field will appear among the clearances as the number of stages changes.?4?Based on ANSYS Workbench coupling platform,the influence of rotational speed on the flow field in the circulating circuit of the test bed was analyzed.It is concluded that:the change of rotational speed generally affects the flow field in the isolation sleeve.After flowing out of the shaft hole at a certain velocity,the fluid disperses evenly at the bottom of the isolation sleeve and reaches the lowest velocity at the outermost edge.In view of the influence of magnetic-thermal effect on the structure and temperature distribution of the magnetic rotor,it is concluded that:?a?.On the isolation sleeve,the temperature,deformation and strain increase linearly and rapidly with the increase of rotational speed.Compared with the speed of 3000r/min,the maximum temperature,deformation and stress increase about 10 times at the speed of 1000r/min.In terms of temperature distribution,the high temperature region mostly concentrates in the corresponding length range with the magnet steel,while there are obvious stratification phenomena at both ends of the cylinder wall.Structurally,the maximum value of deformation is consistent with the high temperature concentration area,and expands evenly outward in the circumference,and decreases gradually in the radial direction to both ends.By comparing the effect of magnetic field and flow field on the stress of isolation sleeve,it can be seen that the magnetic-thermal effect is the main reason leading to the large deformation of isolation sleeve.?b?.On the magnetic rotor body,the stress and deformation increase exponentially with the increase of rotational speed,and distribute is unified in the circumference while the gradient decreases in the axial and radial direction.On the inner magnetic rotor body,the stress normally concentrates on the envelope surface;on the external rotor body,the stress mostly concentrates on the interface with the magnetic steel;on the isolation sleeve,the stress normally concentrates on the length range of the corresponding magnetic steel.Meanwhile,the deformation is the largest.