Centrifugal Pump Rotor Dynamics Study

Abstract

Rotary machines just like other complex technical devices, are the subject to vibrations that can lead to harmful effects during operation, and sometimes to destruction of individual elements, for example, reference nodes . The main source of vibration in such machines is a rotating element - the rotor, to which the centrifugal forces act in presence of shell elements or their residual imbalance. This is the main and inevitable type of vibration of any rotary machine. The unbalanced rotor always oscillates with the reference frequency, that is, the rotation velocity. In this case, the resulting centrifugal forces can cause not only vertical and horizontal vibrations, but also, under certain conditions, axial vibrations. The analysis of the dynamic behavior of the rotor under the influence of these forces should be carried out to any rotary machine both as at the design and operational stages, and so in case of operational accidents. The purpose of this work is to determine the main dynamic parameters and characteristics of the rotor of a centrifugal pump, taking into account the shell elements, determination of critical rotation velocities and the derivation of results in the form of the Campbell diagram with visualization of the rotor motion paths to determine the danger of resonance modes. To achieve this goal, the NASTRAN engineering analysis system of the standardized DMAP procedure "Rotodynamics" was used. The rotor was modeled as a shaft of piecewise constant cross section with shell elements modeled in the form of concentrated masses with inertia of rotation. In the article the results of calculations of two design schemes of a rotor of the pump with fastening the end of a shaft at a guide support, in the form of a caprolon sleeve and at a bearing support are given.

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