Development And Research Of A Compact High Speed Magnetic Pump

In order to meet the needs of vehicle,spaceflight and other fields,and to solve the problems of leakage,heat and wear caused by mechanical seal in traditional centrifugal pump,the dynamic seal of centrifugal pump transmission power is changed into static seal by using magnetic force driving technology.No leakage is achieved in the process of power transfer and good results are obtained.According to the contract commissioned by a certain research institute,a new type of high speed magnetic pump for a new liquid cooling system is studied in this dissertation.The model of the pump studied is GCB500-130.According to the technical requirements,the hydraulic design of the impeller,volute and inducer in the compact magnetic pump is designed,and the structural dimensions of the isolation sleeve and the inner and outer magnetic blocks are determined.Considering that the spiral case of compact magnetic pump is in the form of double volute,six kinds of volute schemes with different diaphragm lengths are designed.The whole flow field and radial force distribution of the pump under different schemes are calculated and compared by ANSYS-CFX.The pump with volute scheme 4 is taken as an example for process and test.In the course of the research,the flow field,external characteristics,pressure pulsation performance and radial force pulsation performance of the pump with the volute scheme under different working conditions are studied by numerical simulation.At the same time,based on the numerical analysis method of multi-field coupling in Workbench,the structural statics and dynamics are analyzed for the main flow passage components,such as the impeller,volute and isolation sleeve.The strain distribution and modes in the magnetic pump are obtained.The rationality and reliability of the structural design for the main flow passage components are verified.The main contents and achievements of this dissertation are summarized as follows:(1)A new type of high speed compact magnetic pump is designed and developed according to the technical requirements.The hydraulic design of impeller and volute of compact magnetic pump is designed,and the structure of each part is designed.As the key part in the process of the torque transfer,the design scheme of internal and external magnetic rotor of magnetic drive is determined by solving the empirical formula of magnetic torque calculation and numerical simulation.In the study,the impeller and the internal magnetic rotor are designed as one body,the isolation sleeve and the pump shaft are designed as a whole,for a smaller volume,a new type of compact magnetic pump with large flow,high head and high speed is designed and developed in this dissertation.(2)Double volute structure is adopted in the new high speed magnetic pump,which can achieve better radial force balance.According to six kinds of volute schemes with different diaphragm lengths,the model of the whole flow field of the pump is constructed and divided by structural mesh.By means of numerical calculation,the variation of flow field in volute case with different schemes is compared,and the influence of changing the length of diaphragm on the external characteristics is analyzed.The results show that the internal flow of the pump is improved under the volute case scheme from 2 to 6,and the tangential pressure of the impeller is symmetrically distributed by the volute case from scheme 4 to 6 compared with the original volute case.Furthermore,the head of the pump using the non-diaphragm volute scheme 1 is the maximum under all flow conditions.When the volute case with diaphragm is adopted,the pump head of each scheme rises with the increase of the diaphragm length.Similar to the change rule of the head,the efficiency of pump increases with the increase of diaphragm length,while the efficiency of pump in volute case without diaphragm is close to that of scheme 4.Taking the volute case scheme 4 as an example,prototype tests are carried out.The internal flow law and external characteristics of the pump under different working conditions are analyzed.The pump performance is tested and evaluated on a test platform for high speed pump.Numerical simulation and experimental results show that the performance of the pump under this scheme could meet the design requirements.(3)Because of the characteristics of large flow rate and high speed,an inducer is designed for the compact magnetic pump to prevent the cavitation.According to the three-dimensional model of inducer,the flow field and cavitation of the inducer are calculated and analyzed by CFX.The results show that the pressure increases gradient from the inlet to the outlet on the surface of the inducer blade,and the velocity increases gradually along the hub to the rim of the wheel.When cavitation occurs in the inducer,the bubble gradually develops into the channel from the inlet edge of the blade near the rim,and slight cavitation has little effect on the performance of the inducer.(4)The pressure pulsation and radial force of impeller are studied.The calculation results of pressure pulsation show that the main frequencies of pressure pulsation in the flow field of impeller and volute are shaft frequency and blade frequency respectively,and the secondary main frequency is respective harmonic frequency.Except for the adjacent area of blade inlet and tongue,there is no effect on the pressure fluctuation of the inducer.The calculation results of radial force show that the radial forces of impeller in volute case scheme from 2 to 6 with diaphragm are obviously reduced compared with the original volute case scheme.When the volute case takes the form of double volute with diaphragm,the radial force of the impeller decreases with the increase of the diaphragm length.When the diaphragm extends to the length shown in option 5,the continued increase in the diaphragm length does not change the radial force.(5)Based on Workbench,the statics and dynamics analysis of the main flow passage components in compact magnetic pump are researched.The results show that the stress and deformation of impeller rotor,volute and isolation sleeve gradually increase with the decrease of flow rate.The maximum deformation of the cylinder wall of the isolation sleeve is much less than the distance between it and the external magnetic rotor.Under different conditions,all components could meet the mechanical performance requirements.In the case of prestressing,the natural frequency of each component is far away from the main frequency of the flow induced excitation.