Special Signal Processing Tools for the Experimental Data of Spiral Vibrations

The occurrence of spiral vibrations in large rotating machines is not a very common phenomenon. However, this kind of shaft vibration, usually caused by rubs between rotating and stationary parts, may give rise to a rather quick and considerable change of the vibration amplitudes. Some well-known methods can be used to study and simulate spiral vibrations, however, further unconventional techniques have been developed by the authors to analyse experimental vibration data of rotating machines that are affected by this phenomenon. The results provided by these innovative techniques can allow the models used by common investigation methods to be developed and optimized. Moreover, they can also be useful to conceive effective corrective actions that can eliminate spiral vibrations. In the paper, the results obtained by applying unconventional techniques to the analysis of stable and unstable spiral vibrations that affected the dynamic behaviour of a large rotating machine, on which brush seals were mounted, are shown and discussed.