Abstract:Abstract: In order to investigate the vibration characteristics of impeller and pump shaft of screw centrifugal pump in operation, the type ZJ-200-25 screw centrifugal pump with double blade was chosen as the study model. A threedimensional mathematical model of fluid flow in the pump was established and the flow was simulated numerically under the design condition. A finite element model for the rotor system of the pump was generated as well. The statics and mode analysis were conducted under the flow field pressure distribution in pump chambers when the rotor was prestressed. The 1st to 6th order natural frequencies and the modes of vibration of the rotor system were obtained. It was showed that the strength of the rotor completely satisfies the design requirement and the maximum stress points were located at the root of blades and the shoulder of shaft. The rotor was rigid, and a natural frequency of rotor system was close to the blade passing frequency of impeller, thus the rotor system design was unreasonable. Therefore, it is necessary to optimize the structure of rotor by altering the position of bearings, resizing shaft diameter and changing material. In that cases, the natural frequency of the rotor will be changed and may be far away from the blade passing frequency.
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