Design Of Multi-stage Centrifugal Pump And Analysis Of Its Structural Characteristics

The multi-stage centrifugal pump designed in this paper is applied to the naval vessel,according to the flow and head provided by the users,the important parameters of the multi-stage centrifugal pump are designed.On the basis of previous similar pump design,the paper determines the overall structure of multi-stage centrifugal pump.The impeller and the volute of outlet section are designed,and the model of multistage centrifugal pump is built by Solidworks for simulation.Flow characteristic of internal flow field of the multi-stage centrifugal pump have great influence on cavitation,efficiency,vibration and noise,it is difficult to measure through the test.In this paper,the Fluent software is used to simulate the fluid flow in the outlet section of the multistage centrifugal pump,the model is divided into grid and boundary conditions are set in Gambit,and the velocity and pressure distribution diagram of the internal flow field in the exit section are obtained after the calculation of the Fluent.The results show that the velocity and pressure distribution in the flow field is not uniform,and the vortex phenomenon occurs at the same time.The vibration noise of the pump is increased,and the efficiency is reduced.To this end,the flow channel model is modified and the simulation calculation is carried out.The flow characteristics of the modified model are better and have no eddy current region.Simulation determines the dimensions of the impeller and volute shape of the outlet which provides a theoretical basis for determining the multistage centrifugal pump structure size.The pressure of outlet section and the middle part of multistage centrifugal pump outlet is higher.Static analysis is carried on by ANSYS software,which checks the strength and stiffness of the outlet section and the middle section.Simulation finally determines its structure size.In order to ensure the multistage centrifugal pump in operation with less vibration and noise,the modal analysis of the pump body,rotor system,isolated sleeve of the multistage centrifugal pump are carried out,and get the each order natural frequency and vibration shape diagram.Compared the minimum order natural frequency of the simulation with the excitation frequency in the working environment of the multi-stage centrifugal pump,the results show that the natural frequency of pump components are higher than that of the environment vibration frequency,resonance phenomenon does not occur which ensures the stability of the normal operation of the pump.Pump components are subjected to sudden shock which resonance phenomenon may occur.The paper analyze the vibration characteristics and effect of the pump body,rotor system and isolated sleeve when resonance phenomenon occurs,which provides a theoretical basis for the structure design of parts.To this end,the flow channel model is modified and the simulation calculation is carried out.The flow characteristics of the modified model are better and have no eddy current region.Multi-stage centrifugal pump which used in warship needs to have high reliability and good work in high humidity,salt fog and corrosive environment.In view of the reliability design of multi-stage centrifugal pump,the manufacturing principle of reliability design and the criterion of environmental adaptability are established.The reliability of multi-stage centrifugal pump is predicted,the life and reliability of the system are calculated by the theory of reliability prediction.The calculation results show that the pump has good reliability and can meet the requirements life of the user.The paper analyzes the failure mode in the pump parts and gives the classification of the fault mode.In the end,the paper puts forward measures to prevent the occurrence of faults.