Unsteady hydraulic simulation of the cavitating part load vortex rope in Francis turbines

HYPERBOLE Symposium 2017 (HYdropower plants PERformance and flexiBle Operation towards Lean integration of new renewable Energies)

Brammer, J.^1 ; Segoufin, C.^1 ; Duparchy, F.^1 ; Lowys, P.Y.^1 ; Favrel, A.^2 ; Avellan, F.^2

GE Renewable Energy, Hydro Solutions, 82 Avenue Léon Blum-BP75, 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;    Cavitation conditions;    FEA calculations;    Operating points;    Part load operation;    Pressure fluctuation;    Unsteady hydraulics;    Unsteady loading;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/813/1/012020/pdf
DOI  :  10.1088/1742-6596/813/1/012020

来源: IOP

【 摘 要 】

For Francis turbines at part load operation a helical vortex rope is formed due to the swirling nature of the flow exiting the runner. This vortex creates pressure fluctuations which can lead to power swings, and the unsteady loading can lead to fatigue damage of the runner. In the case that the vortex rope cavitates there is the additional risk that hydro-acoustic resonance can occur. It is therefore important to be able to accurately simulate this phenomenon to address these issues. In this paper an unsteady, multi-phase CFD model was used to simulate two part-load operating points, for two different cavitation conditions. The simulation results were validated with test-rig data, and showed very good agreement. These results also served as an input for FEA calculations and fatigue analysis, which are presented in a separate study.