Analysis of the part load helical vortex rope of a Francis turbine using on-board sensors

9th International Symposium on Cavitation

Duparchy, F.^1 ; Favrel, A.^2 ; Lowys, P.-Y.^1 ; Landry, C.^2 ; Müller, A.^2 ; Yamamoto, K.^2 ; Avellan, F.^2

Alstom Hydro France, 82 Av. Léon Blum, Grenoble Cedex 9

38041, France^1

EPFL Laboratory for Hydraulic Machines, Avenue de Cour 33 bis, Lausanne

1007, Switzerland^2

关键词: Acoustic resonance;    Excitation sources;    Helical vortices;    Mechanical behaviour;    On-board measurements;    Precession frequency;    Pressure fluctuation;    Synchronous components;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/656/1/012061/pdf
DOI  :  10.1088/1742-6596/656/1/012061

来源: IOP

【 摘 要 】

The cavitation helical vortex rope arising at Francis turbine partial load induces pressure fluctuations at the rope precession frequency, which can be decomposed into two components; the convective one and the synchronous one. The latter acts as an excitation source for the hydraulic system and is amplified in case of resonance. The present paper aims to highlight the impact of both components on the mechanical behaviour of the runner by performing on-board measurements. It is shown that the use of on-board pressure sensors enables to naturally separate the components of the pressure fluctuations. In addition, the synchronous component has little impact on the mechanical behaviour of the runner, even for the case in which hydro-acoustic resonance occurs.