Study On Fluid-Solid Coupling Dynamic Characteristics Of High Speed Centrifugal Pump

As the development of civil economy, high speed centrifugal pump is wildly used in oil refining,petrochemical,chemical industry and aeronautics and astronautics. Inducer and impeller are the core components of energy conversion for high speed centrifugal pump.The interaction between blades and viscous flow field is the causes of the vibrations of the blades, and the strong vibrations can lead to the oceurrence of fatigue fracture and dynamic loss stability of the blades. Therefore, the study on the dynamic characteristics of the blades is of great significance to understand the flow-induced vibration mechanism, to prevent resonance of the blades, and to ensure safty and stability of the unit.Research the inner flow and performance predicting based on numberical simulation, analysis on the rigidity and vibration characteristics of the blades of inducer and impellers, and the effect of the deformed impeller to the head, efficiency and axial power.The main work and research results of the paper consist of:1.The development and research situation of the high speed centrifugal pump were introduced and the problems existed were analyzed briefly, and the specific research program was identified.Fundamental theory of hydraulic design of high speed centrifugal pump was elaborated and was applied to design the inducer,the impellers and the volute.2. The modling of the impeller and the method of mesh and setting of boundary conditions are expatiated by using Pro/E and ANSYS Workbench software.And the control equations of fluid and structure coupling fields, discrete solving methods, simulation theory of multipase flow and mesh technology were discussed.The numerical investigation of internal flow that was based on calculation Navier-Stokes equation and standardκ-εturbulence model was carried out by using CFX software. Therefor the water pressure on the blade was computed.3.We analyzed the induer and the impeller's static and modal characteristic adopting the sequential coupling method with the software ANSYS Workbench, and analyzed the possibility which the inducer and the impellers appear resonancein the runing state, and comparative analysis was done for the vibration characteristic in the water and in the air. The results indicate the largest equivalent stress on the blade of the inducer appears in the conjoin of the hub and the blade which has a larger change in gradient of stress and which is prone to fatigue failure. The largest defomation appears in the exoloma of the blade, that is the sensitive areas of the blade vibration. The main stress concentration region of the impeller is in the inlet side of the blade, and the largest defomation appears in the outlet side of the blade.The results show the nature frequencies of the components is smaller in the water than in the air; the working enviroment would have effect on the nature frequencies. In conclusion the interaction between the fluid and solid shoud be considered when we analyze the high speed centrifugal structural.4. The affect of centrifugal force and the water pressure to the modal were calculated with the software ANSYS Workbench, and the modal of the inducer and the impeller when they run in the water and the affect of the deformed impellers to the pump performance was displayed. The results indicate that the kinds of order frequencies have some small change, and the affect to the nature frequenceies and vibration mode were small. We analyze the water pressure of the blade before the defomation and after the defomation in the design condition, and singnificant deformations occured when the water pressure loaded on the blades.And the head,axial power and efficiency of the pump all decreased.