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Rotor-Stator Contact in Polygonal Backup Bearings

(www.u-sim.de)

PHD thesis of Ulrich Simon to become a Dr.-Ing. from Technical University of Braunschweig, Germany, 2001, at the Institute of Engineering Mechanics, Director: Prof. Dr. E. Brommundt.

Abstract

Backup bearings are used to limit the radial displacement of rotors.  These bearings are active at emergency situations only.  Common bearings are round shaped.  In this type friction between the rotor and the bearing can cause servere self exited movements, which are charactericed by high speed counterwirl movements of the rotor center leading to great unbalances.  Using polygonal backup bearings instead the speed and unbalances of the rotor movements can be reduced.

A three sided backup bearing shows advantages vs. a common round shaped bearing.

About the Video

The video shows an experimental rotor, which I used as part of my PHD project at TU Braunschweig, Germany.

In three subsequent steps you will see periodic self-excited movements of the rotor after a first enforced contact into the two different backup bearings: 

  Fanglagertyp Drehzahl Bewegung
1. Round 2,0 R/sec ->  Backward whirl
2. Round 5,0 R/sec ->  ... with dangerous vibrations
3. Threesided 5,0 R/sec ->  ... with a much smoother run

The movement in the new three-sided backup bearing can reduce the dangerous vibrations significantly compared to those observed in a usual round bearing.

Keywords

Retainer Bearing, Auxiliary Bearing, Emergency Bearing, Backup Bearing, Touchdown Bearing, Rotor-Stator Rub, Backward Whirl, Reverse Whirl, Inverse Precession, Full Reverse Precession Rub, Dry Friction Whip, Dry Friction Counter Whirl.

Links and Downloads

Dissertation

PHD thesis Simon (w. perm. of VDI-Verlag)

Slides

Prasentation