Numerical Simulation Of Effect Of Inducer On Cavitation Of Centrifugal Pump

Centrifugal pumps are used in a wide range of applications,including irrigation,petrochemicals,light industry,urban water supply,marine industry and mining.In actual use,cavitation largely limits the efficiency and performance of centrifugal pumps.At present,the main measure to prevent pump cavitation is to increase the NPSH of the device.However,to fundamentally improve the anti-cavitation performance of the pump,it is necessary to install an inducer and optimize the structure.In this paper,a single-stage single-suction centrifugal pump with inducer capable of conveying clean water and medium similar to clear water is designed.The 3D solid modeling of the whole flow field is carried out by using Proe software,and then the model is imported into ANSYS software to simulate and obtain Impeller gas volume cloud,Inducer leaf speed vector and Isosurface map with a bubble volume fraction of 10% on the inducer under different NPSH.At the same time,the cavitation curve of the centrifugal pump with inducer is predicted by processing and analyzing the simulated data.Combined with the above numerical simulation method,the structural parameters such as the number of leaves and the sweep angle of the inducer as well as the assembly distance between the inducer and the centrifugal pump are changed to simulate the model of the combined centrifugal pump,and then the optimal centrifugal pump with inducer structure is obtained by analyzing the simulation results.The results show:(1)After the inducer is installed,the distribution range of the low pressure region on the centrifugal pump impeller is significantly reduced,the critical NPSH is greatly decreased,and when the cavitation emerges,the centrifugal pump head with the inducer drops more slowly.(2)The single-blade inducer has structural asymmetry,the blade does not work well on the axial section fluid,and the operation is unstable.The two-blade inducer has less blades,the displacement between the leaves is small,and alternating cavitation may occur.The three-blade inducer can ensure the uniform distribution of fluid velocity and pressure,control the bubble in the rim region,prevent diffusion,and give the liquid at the inlet of the main impeller a large rotating torque,which reduces the relative speed and can effectively improve the pump anti-cavitation performance.(3)When the sweep angle is small,the inlet liquid pressurization process is short,and the movement of bubbles to the rim is slow.When the sweep angle is large,the import angle increases,and the impact of the liquid at the inlet on the inducer also increases,resulting in more severe cavitation and reduction of cavitation performance.The best inducer sweep angle for this simulation is 120°.(4)When the assembly spacing is too large,the backflow and leakage of the main impeller are more serious.When the assembly sapcing is too small,the displacement between the inducer and the impeller increases,with the fluid turbulence enhanced.There is a strong turbulence near the area of the rear cover,and the bubbles are not easy to diffuse.The simulation study found that the optimal assembly spacing was 10 mm.