Preprint Article Version 1 This version is not peer-reviewed

Numerical Study on the Dynamic Behavior of a Francis Turbine Runner Model with a Crack

Version 1 : Received: 30 April 2018 / Approved: 2 May 2018 / Online: 2 May 2018 (12:14:30 CEST)

A peer-reviewed article of this Preprint also exists.

Zhang, M.; Valentin, D.; Valero, C.; Egusquiza, M.; Zhao, W. Numerical Study on the Dynamic Behavior of a Francis Turbine Runner Model with a Crack. Energies 2018, 11, 1630. Zhang, M.; Valentin, D.; Valero, C.; Egusquiza, M.; Zhao, W. Numerical Study on the Dynamic Behavior of a Francis Turbine Runner Model with a Crack. Energies 2018, 11, 1630.

Journal reference: Energies 2018, 11, 1630
DOI: 10.3390/en11071630

Abstract

The crack in the blade is the most common type of fatigue damage for Francis turbines. However, the crack sometimes is difficult to be detected in time using the current monitoring system even when the crack is very large. To better monitor the crack, it is imperative to research the effect of a crack on the dynamic behavior of a Francis turbine. In this paper, the dynamic behavior of a Francis turbine runner model with a crack was researched numerically. The intact numerical model was first validated by the experimental data available. Then, a crack was created at the intersection line between one blade and the crown. The change in dynamic behavior with increasing crack length was investigated. Crack-induced vibration localization theory was used to explain the dynamic behavior changes due to the crack. Modal analysis showed that the adopted theory could basically explain the modal behavior change due to the crack. The FFT results of the modal shapes and the localization factors (LF) were used to explain the forced response changes due to the crack. Based on the above analysis, the challenge of crack monitoring was analyzed. This research can also provide some references for more advanced monitoring technologies.

Subject Areas

Francis turbine; crack; dynamic behavior; vibration localization; lumped parameter mode; localization factor; forced response

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