Hydraulic instability onset detection in Kaplan turbines by monitoring shaft vibrations

Pennacchi, P., Borghesani, P., Chatterton, S., & Vania, A. (2012) Hydraulic instability onset detection in Kaplan turbines by monitoring shaft vibrations. In Proceedings of the ASME Design Engineering Technical Conference, ASME, Chicago, Illinois, USA, pp. 715-722.

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Abstract

Design of hydraulic turbines has often to deal with hydraulic instability. It is well-known that Francis and Kaplan types present hydraulic instability in their design power range. Even if modern CFD tools may help to define these dangerous operating conditions and optimize runner design, hydraulic instabilities may fortuitously arise during the turbine life and should be timely detected in order to assure a long-lasting operating life.

In a previous paper, the authors have considered the phenomenon of helical vortex rope, which happens at low flow rates when a swirling flow, in the draft tube conical inlet, occupies a large portion of the inlet. In this condition, a strong helical vortex rope appears. The vortex rope causes mechanical effects on the runner, on the whole turbine and on the draft tube, which may eventually produce severe damages on the turbine unit and whose most evident symptoms are vibrations. The authors have already shown that vibration analysis is suitable for detecting vortex rope onset, thanks to an experimental test campaign performed during the commissioning of a 23 MW Kaplan hydraulic turbine unit.

In this paper, the authors propose a sophisticated data driven approach to detect vortex rope onset at different power load, based on the analysis of the vibration signals in the order domain and introducing the so-called "residual order spectrogram", i.e. an order-rotation representation of the vibration signal. Some experimental test runs are presented and the possibility to detect instability onset, especially in real-time, is discussed.

Impact and interest:

5 citations in Scopus
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2 citations in Web of Science®

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ID Code: 66497
Item Type: Conference Paper
Refereed: No
Additional Information: ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference.
Volume 1: 24th Conference on Mechanical Vibration and Noise, Parts A and B
Additional URLs:
Keywords: Hydraulic instability, condition monitoring, Envelope analysis, Order tracking
DOI: 10.1115/DETC2012-70963
ISBN: 9780791845004
Subjects: Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > ELECTRICAL AND ELECTRONIC ENGINEERING (090600) > Signal Processing (090609)
Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > MECHANICAL ENGINEERING (091300) > Dynamics Vibration and Vibration Control (091304)
Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > INTERDISCIPLINARY ENGINEERING (091500) > Fluidisation and Fluid Mechanics (091504)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2012 by ASME
Deposited On: 22 Jan 2014 00:26
Last Modified: 01 Apr 2014 23:19

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