Dynamics of unbalanced rotor mounted on roller bearings

Аuthors

Leontiev M. K.^1*, Snetkova E. I.^1**, Degtiarev S. A.^2***

1. Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
2. Scientific and technical centre of rotor dynamic Alfa-Tranzit Co., Ltd, 1, Leningradskaya street, Khimky, Moscow region, 141400, Russia

*e-mail: lemk@alfatran.com
**e-mail: ekaterina-snetkova@ya.ru
***e-mail: degs@alfatran.com

Abstract

Object and purpose of the study

The dynamic characteristics of an unbalanced rotor system with roller radial bearing in the nonlinear statement were investigated. The algorithm to simulate the radial roller bearing in tasks of rotor dynamics was developed. It was programmed as a module in the software system Dynamics R4 intended for modeling and analysis rotor dynamics of turbomachinery.

Methodology

The rotor system consisting of the point «case» with mount, the point «rotor» and the nonlinear bearing was investigated. Mathematical model of the nonlinear bearing is based on the theory of Hertz and considers bearing clearance, the number and inertia of rolling elements, the weight of the rotor and unbalanced force.

Findings

During start up from 0 to 30000 rpm and following shut down to zero rpm several transition stages can be identified: the area of chaotic motion in the initial phase of the motion (rotor is on the ring of bearing), the area at which the rotor becomes a stable near-circular motion under the action of the unbalance force, the area on which there is a transition through resonance and the subsequent behavior of the rotor is accompanied by slight unbalance forced oscillations and the intense chaotic traffic with following passing in parametric oscillations. Study the chaotic motions of the rotor noted that for the normal operation of the bearing should be a balance between the forces acting on the bearing (weight, unbalanced forces, the forces of inertia) and the clearance in the bearing.

Originality/value

The results show the need for the preliminary study of any dynamic rotor systems in nonlinear statement in order to make a correct choice of bearing type, size, clearance, minimum rotor unbalance ets. That is, the parameters determining the stable and reliable operation of the rotor system and eventually, bearings durability.

Keywords:

roll bearing model, clearance, stiffness, rotor dynamics, Dynamics R4, nonlinear analysis

References

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