Fluid-structure interaction of a 7-rods bundle: Benchmarking numerical simulations with experimental data

Bertocchi, Fulvio; Rohde, M.; Santis, Dante De; Shams, A.; Dolfen, Henri; Degroote, Joris; Vierendeels, Jan

doi:10.1016/j.nucengdes.2019.110394

Cited by 17 publications

(3 citation statements)

References 23 publications

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“…The dimensions and material properties are listed in Table 1. For a more detailed description of the experimental facility and measurement campaign, the reader is referred to Bertocchi et al (2019).…”

Section: Methodsmentioning

confidence: 99%

Vibrations in a 7-rod bundle subject to axial flow: Simulations and experiments

Dolfen

Bertocchi

Rohde

et al. 2019

Nuclear Engineering and Design

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Being able to quantify mechanical vibrations is of key importance for the safety of nuclear power plants, as they are able to induce damage. In this work, numerical simulations are used to compute water flow and vibration in a densely packed bundle of 7 rods, mimicking an experimental setup. This flow configuration is chosen to resemble the coolant flow through a nuclear reactor core. Because of the wall proximity, a considerable velocity difference between the narrow gaps and the subchannels exists, with an inflection point in the velocity profile. This yields an unstable situation, and large vortices are continuously created through a mechanism similar to the Kelvin-Helmholtz instability. The vortex streets in between the rods are associated with a fluctuating pressure field, causing vibrations of the rods. The experimental setup contains 7 steel cylinders, encased in a hexagonal duct. The central rod contains a section where the steel is replaced by a water-filled silicone tube, clamped at both extremes to the steel rod, and the vibrations of this section are examined. The numerical approach consists of coupled fluid-structure interaction (FSI) simulations, with the flow being modelled using computational fluid dynamics (CFD) and the structure using computational solid mechanics (CSM). The available experimental data consist of Laser Doppler Anemometry (LDA) measurements and high-speed camera footage of the wall movement of the silicone rod. Equivalent data is collected from the numerical simulations. The simulations are repeated for different flow rates. The frequency spectrum of the coherent structures, and the frequency and amplitude of the wall movement are compared for each operating point, as well as their trend as a function of the flow rate. The dominant frequencies found in the simulation results were similar to the experimental results, although slightly higher. They also showed a linear trend, just like the experiments. A larger mismatch was present for the structural response, the frequencies found using the FSI model being more than twice as high.

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Section: Methodsmentioning

confidence: 99%

Vibrations in a 7-rod bundle subject to axial flow: Simulations and experiments

Dolfen

Bertocchi

Rohde

et al. 2019

Nuclear Engineering and Design

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“…Several possible reasons for the mismatch were identified, but will need future investigations to draw conclusion. In particular, the fixation and/or material properties of the transparent material, the stiffness of the rods, the modeling of the water filling of the rods, and dimensional tolerances of the components of the experimental set-up might play a role [28].…”

Section: Core Thermal Hydraulicsmentioning

confidence: 99%

SESAME project: advancements in liquid metal thermal hydraulics experiments and simulations

Tarantino

Roelofs

Shams

et al. 2020

EPJ Nuclear Sci. Technol.

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Liquid metal cooled reactors are envisaged to play an important role in the future of nuclear energy production because of their possibility to use natural resources efficiently and to reduce the volume and lifetime of nuclear waste. Sodium and Liquid lead (-alloys) are considered the short and long term solution respectively, as coolant in GEN-IV reactor. Thermal-hydraulics of liquid metals plays a key role in the design and safety assessments of these reactors. Therefore, this is the main topic of a large European collaborative program (the Horizon 2020 SESAME) sponsored by the European Commission. This paper will present the progress in the project with respect to liquid metal cooled reactor thermal-hydraulics (liquid metal heat transfer, fuel assembly thermal-hydraulics, pool thermal-hydraulics, and system thermal-hydraulics). New reference data, both experimental and high-fidelity numerical data is being generated. And finally, when considering the system scale, the purpose is to validate and improve system thermal-hydraulics models and codes, but also to further develop and validate multi-scale approaches under development.

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“…Next to increasing confidence in simulation results of a realistic reactor envi-ronment, also a second reason to resort to UQ methods can be given. Geometrical or operational uncertainties are present in experiments (Roelofs et al, 2019) and can convolute numerical validations, as was suggested by Dolfen et al (2019) and Bertocchi et al (2020). This is especially the case because FIV experiments are typically complicated to construct.…”

Section: Introductionmentioning

confidence: 96%