Magnetic drive pump has gotten great achievement and has been widely used in some special fields. Currently, the researches on magnetic drive pump have focused on hydraulic design, bearing, axial force in China, and a new magnetic drive pump with low flow and high head have been developed overseas. However, low efficiency and large size are the common disadvantages for the magnetic drive pump. In order to study the performance of high-speed magnetic drive pump, FLUENT was used to simulate the inner flow field of magnetic drive pumps with different rotate speeds, and get velocity and pressure distributions of inner flow field. According to analysis the changes of velocity and pressure to ensure the stable operation of pump and avoid cavitation. Based on the analysis of velocity and pressure, this paper presents the pump efficiency of magnetic drive pumps with different rotated speeds by calculating the power loss in impeller and volute, hydraulic loss, volumetric loss, mechanical loss and discussing the different reasons of power loss between the magnetic drive pumps with different rotated speeds. In addition, the magnetic drive pumps were tested in a closed testing system. Pressure sensors were set in inlet and outlet of magnetic drive pumps to get the pressure and the head, while the pump efficiency could be got by calculating the power loss between the input power and the outlet power. The results of simulation and test were similar, which shows that the method of simulation is feasible. The proposed research provides the instruction to design high-speed magnetic drive pump.

To improve the hydraulic performance in an ultra-low specific speed magnetic drive pump, optimized design of impeller based on orthogonal test was carried out. Blades number Z, bias angle in peripheral direction of splitter blades θ_s, inlet diameter of splitter blades D_si, and deflection angle of splitter blades α were selected as the main factors in orthogonal test. The credibility of the numerical simulation was verified by prototype experiments. Two optimized impellers were designed through the analysis of orthogonal test data. The internal flow field, pressure fluctuation, and radial force were analyzed and compared between optimized impellers and original impeller. The results reveal that impeller 7 (Z = 5, θ_s = 0.4θ, D_si = 0.75D₂, α = 0°) could increase the head and efficiency, compared to the original impeller, by 2.68% and 4.82%, respectively. Impeller 10 (Z = 5, θ_s = 0.4θ, D_si = 0.55D₂, α = 0°) reduced the head by 0.33% and increased the efficiency by 8.24%. At design flow rate condition, the internal flow of impeller 10 was the most stable. Peak-to-peak values of pressure fluctuation at the volute tongues of impeller 7 and impeller 10 were smaller than those of the original impeller at different flow rate conditions (0.6 Q_d, 1.0 Q_d and 1.5 Q_d). Radial force distribution of impeller 10 was the most uniform, and the radial force variance of impeller 10 was the smallest.

Based on the shear stress transport (SST) turbulence model, the influence of different outlet pipe angles on the head and efficiency of a boiler circulating pump was analyzed. When the outlet pipe angle changed from 115° to 130°, the head and efficiency of the pump reduced significantly. The boiler circulating pump with 115° outlet pipe angle was selected as the further research object, and the reliability of the numerical simulation was verified by experiments. The transient flow of the prototype pump under the design flow rate condition (1.0Q_d) and four other flow rate conditions (0.6Q_d, 0.8Q_d, 1.2Q_d, and 1.4Q_d) was studied. The results show that, under the conditions of design flow and large flow rate (1.0Q_d, 1.2Q_d, and 1.4Q_d), the centrality and regularity of radial force distribution are obviously better than those of small flow rate (0.6Q_d, 0.8Q_d). The leakage of the rear seal ring is less than that of the front seal ring under five flow rate conditions. As the flow rate increases, the leakage of front and rear seal rings decreases, and the leakage ratio of front and rear seal rings increases. The energy loss of the rear cover plate is greater than the energy loss of the front cover plate under five flow rate conditions. With the increase in flow rate, the total loss energy of the prototype pump decreases first and then increases, and the energy loss of the disc becomes larger and larger.

To research the effects of the blade outlet angle on the performance and the radial force of the marine pump, the unsteady numerical simulation of the four different models is carried out. The radial forces on the impeller and the blades are obtained under different flow rate conditions. The time and frequency domain characteristics of radial resultant force on the impeller and the blades are analyzed and those of the impeller torque are researched. The results show that the radial forces of the impeller and the blades increase with the increase of the blade outlet angle at the same flow rate. With the same blade outlet angle, the radial forces decrease with the increase of the flow rate. The roundness of radial force vector diagram becomes more obvious with the decrease of the blade outlet angle. The root mean square (RMS) of radial force on the blades is about 30% of that on the impeller. The main frequency of radial force on the impeller and the blades is the axial passing frequency (APF), and that of impeller torque is the blade passing frequency (BPF), and there are peaks at the blade frequency multiplier. At the same flow rate, the main frequency and maximum fluctuation amplitudes on the impeller and the blades increase with the increase of the blade outlet angle. Meanwhile, the impeller torque increases with the increase of the blade outlet angle. With the same blade outlet angle, the main frequency, maximum fluctuation amplitudes, and the impeller torque decrease with the increase of the flow rate. The amplitude difference decreases with the increase of the flow rate. The blade outlet angle has an obvious greater influence on the radial forces and fluctuation at the small flow rate. The vibration test shows that the vibration intensities of model 25 and model 35 are less than 2.5 mm/s, and the vibration intensity of model 25 is about 0.2 mm/s less than that of model 35.

When multistage canned pump works, the temperature rise of the canned motor is high. The designing of the cooling circuit is critical for the performance of the multistage canned pump. The cooling circulation circuit is designed for DPB40-50 × 8 multistage canned pump, and numerical simulation method is adopted. The whole flow domain is modeled by CREO2.0, and calculated and analyzed by CFX14.0. The information of temperature, flow field, pressure distribution in the canned sleeve gap where temperature changed greatly were obtained, the convective heat transfer coefficient between fluid and motor, and the flow rate of the cooling fluid were also gained. The results show that: Under the design condition, the temperature rise of the cooling circuit inside the shielded motor is less than 3K, which can cool the shielded motor very well. The convective heat transfer coefficient of the wall surface of the stator and rotor shielding sleeve, the flow field and thermal field were analyzed, which can reflect the forced convection heat transfer characteristics of the fluid in the canned sleeve gap. The flow of the cooling fluid is changing with different working condition and reached the peak of temperature at the outlet of the canned sleeve gap. The cooling cycle flow are related with the pressure at the drainage hole directly. It can be also concluded that the cooling circuit can satisfy the requirements of the multistage canned pump.

In order to balance axial forces on stamping-welding canned motor pump for safe and reliable operation, the type PBCY80-65-160 pump was selected as the computational model. Combined with various reasons why axial forces of the pump were generated, the theoretical calculation and methods of numerical simulation were chosen to analyze the size, directions and rules of axial force. At the same time, the distribution and trend of the axial force components of the impeller under different working conditions are studied whether there is the balance hole or not. The results show that, in the theoretical calculation and numerical simulation calculation, the gap and internal impact loss of the internal flow field of axial forces were neglected when the internal flow of the motor was seen as an ideal flow through the resistant elements. Hence, it could not fully represent the internal pressure distribution of the pump, which caused the calculated data a little larger than simulated data. Also, the method of combining the balance hole and impeller rear seal ring could effectively balance the axial force and extend the service life of stamping-welding canned motor pump.