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COUPVIB - Coupled vibrations in vertical rotors

Published: 15 January 2010

Case example: Hydropower rotors (SVC-Project)



Coupling is a well known reason of instability in rotating machinery. The fact is that the attempt to free rotating machinery from coupled motions is just an idealization than a reality. This is due to the complexity of the reasons of coupling which mainly depend on the machinery hardware: material properties, fluid-structure interaction, error in
assembling and manufacturing processes (components geometrical irregularities). Besides the named reasons, external applied loads may also cause coupling in rotating machinery, but these ones can still be controlled and adjusted.

The research focuses on vertical machines, because these ones are considered more unstable due to the total lack (or low) stabilizing radial static gravitational load
compared to horizontal machines.


The following systematic procedure is going to be used in order to achieve the goals of the project:

1) Analytical study

  • Coupling due to bearings type/design.
  • Torsional, lateral and axial vibrations: The level of their coupling in vertical rotors.
  • External excitation force (imbalance force) and gyroscopic effect as sources of coupling.
  • Coupling due to shape deviations(geometric irregularities) and misalignment of parts (in thrust bearing).

2) Experiment

The simulated models are going to be validated by comparison with the experiment results.

Expected results

The expected results will show how the analyzed couplings would affect the dynamics of the
rotating machinery and especially the vertical ones. The obtained results would serve as a
guide in design, manufacturing and assembling processes of reliable machines.