Dynamics of the precessing vortex rope and its interaction with the system at Francis turbines part load operating conditions

A. Favrel, A. Müller, C. Landry, J. Gomes, K. Yamamoto, F. Avellan

Research output: Contribution to journalConference article

9 Citations (Scopus)

Abstract

At part load conditions, Francis turbines experience the formation of a cavitation vortex rope at the runner outlet whose precession acts as a pressure excitation source for the hydraulic circuit. This can lead to hydro-acoustic resonances characterized by high pressure pulsations, as well as torque and output power fluctuations. This study highlights the influence of the discharge factor on both the vortex parameters and the pressure excitation source by performing Particle Image Velocimetry (PIV) and pressure measurements. Moreover, it is shown that the occurrence of hydro-acoustic resonances in cavitation conditions mainly depend on the swirl degree of the flow independently of the speed factor. Empirical laws linking both natural and precession frequencies with the operating parameters of the machine are, then, derived, enabling the prediction of resonance conditions on the complete part load operating range of the turbine.

Original languageEnglish
Article number012023
JournalJournal of Physics: Conference Series
Volume813
Issue number1
DOIs
Publication statusPublished - 2017 Apr 4
EventHYdropower Plants PERformance and FlexiBle Operation Towards Lean Integration of New Renewable Energies Symposium, HYPERBOLE 2017 - Porto, Portugal
Duration: 2017 Feb 22017 Feb 3

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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