Experimental modal analysis of disk-like rotor–stator system coupled by viscous liquid

Weder, Mario; Horisberger, Beat; Monette, Christine; Sick, Mirjam; Dual, Jürg

doi:10.1016/j.jfluidstructs.2019.05.003

Cited by 15 publications

(10 citation statements)

References 19 publications

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“…Weder et al [9] investigated a configuration of two flexible circular discs experimentally of which one (rotor) is fully submerged in water and can be rotated in proximity of a circular, thin casing wall (stator). A schematic representation of their setup is shown in Figure 2 (a).…”

Section: Mode Split Phenomenonmentioning

confidence: 99%

“…Their analytical approach was extended by Berthet [8] to account for radial wall proximity and stator disc flexibility. Detailed experimental results on the mode split phenomenon with a flexible rotor and stator are presented by Weder [9]. Experimental results on the phenomenon of the rotating disc mode split such as [3] and [9] are fundamental to explore the underlying physics and to provide data for the validation of analytical and numerical models.…”

Section: Introductionmentioning

confidence: 99%

“…Detailed experimental results on the mode split phenomenon with a flexible rotor and stator are presented by Weder [9]. Experimental results on the phenomenon of the rotating disc mode split such as [3] and [9] are fundamental to explore the underlying physics and to provide data for the validation of analytical and numerical models. Analytical solutions to the disc mode split phenomenon are useful in identifying the basic physics and the main parameters of influence ( [1], [4]).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Eigenfrequencies of rotating discs in dense fluid: imposed modal motion approach

Nennemann

Monette

Braun

et al. 2022

IOP Conf. Ser.: Earth Environ. Sci.

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The mode split on disc like structures rotating in a dense fluid leads to a deviation of eigenfrequencies at high rotational speeds compared to their values in still water. Predicting eigenfrequencies correctly is essential to avoid fatigue cracks on prototype turbine runners. Analytical models for simple geometric configurations and complex numerical models using fully coupled fluid structure interaction to predict the mode split on arbitrary geometries exist. We are presenting a complementary approach of intermediate complexity applicable to arbitrary geometries. Mode shapes and modal parameters are computed by finite element analysis in still water. These mode shapes are imposed with a harmonic variation in time during an unsteady computational fluid dynamics computation. From the interaction between the flow and the modal motion, the modal force and the modal work can be computed. These can be converted into added modal mass and hydrodynamic damping and further into the shift of the eigenfrequency under rotation due to the fluid for a given mode. The tendencies of the frequencies with rotation compare reasonably well with experimental data. The numerical method can be applied to disc rotation speeds far beyond the range of experimental data revealing interesting tendencies and a phenomenological interpretation of the cause of the mode split.

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Section: Mode Split Phenomenonmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Eigenfrequencies of rotating discs in dense fluid: imposed modal motion approach

Nennemann

Monette

Braun

et al. 2022

IOP Conf. Ser.: Earth Environ. Sci.

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“…Typically, in hydraulic turbines, this issue arises when the top part of the runner vibrates with the top casing surface (Weder et al, 2019). This makes rotorstator coupling especially relevant for future work on the matter; possibly by adapting our numerical model.…”

Section: Conclusion 330mentioning

confidence: 99%

“…Numerical Fluid-Structure Interactions (FSI) models using Finite Element Analysis (FEA) are powerful tools for the structural design analysis of these machines (Dompierre & Sabourin, 2010;Hübner et al, 2016). This method is applicable to natural frequency prediction of standing circular plates (Hengstler, 2013), disk-fluid-disk systems, rotor-stator systems (Specker, 2016;Weder et al, 2016Weder et al, , 2019, and rotating disks in fluid (Weber & Seidel, 2015). This shows that the application range of numerical FSI is extremely broad, and widely used to deal with disk frequency prediction.…”

Section: Introductionmentioning

confidence: 99%

Modal analysis of a spinning disk in a dense fluid as a model for high head hydraulic turbines

Louyot

Nennemann

Monette

et al. 2020

Journal of Fluids and Structures

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In high head Francis turbines and pump-turbines in particular, Rotor Stator Interaction (RSI) is an unavoidable source of excitation that needs to be predicted accurately. Precise knowledge of turbine dynamic characteristics, notably the variation of the rotor natural frequencies with rotation speed and added mass of the surrounding water, is essential to assess potential resonance and resulting amplification of vibrations. In these machines, the disk-like structures of the runner crown and band as well as the head cover and bottom ring give rise to the emergence of diametrical modes and a mode split phenomenon for which no efficient prediction method exists to date. Fully coupled Fluid-Structure Interaction (FSI) methods are too computationally expensive; hence, we seek a simplified modelling tool for the design and the expected-life prediction of these turbines.We present the development of both an analytical modal analysis based on the assumed mode approach and potential flow theory, and a modal force Computational Fluid Dynamics (CFD) approach for rotating disks in dense fluid. Both methods accurately predict the natural frequency split as well as the natural frequency drift within 7.9% of the values measured experimentally. The analytical model explains how mode split and drift are respectively caused by linear and quadratic dependence of the added mass with relative circumferential velocity between flexural waves and fluid rotation.

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Experimental and theoretical investigations of the lateral vibrations of an unbalanced Jeffcott rotor

Alsaleh

Sedighi

Ouakad

2020

Front. Struct. Civ. Eng.

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Experimental modal analysis of disk-like rotor–stator system coupled by viscous liquid

Cited by 15 publications

References 19 publications

Eigenfrequencies of rotating discs in dense fluid: imposed modal motion approach

Eigenfrequencies of rotating discs in dense fluid: imposed modal motion approach

Modal analysis of a spinning disk in a dense fluid as a model for high head hydraulic turbines

Experimental and theoretical investigations of the lateral vibrations of an unbalanced Jeffcott rotor

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