TY - JOUR
T1 - Large Eddy Simulation of a 5 × 5 rod bundle
T2 - Impacts of a central control rod thimble tube
AU - Kraus, Adam
AU - Merzari, Elia
AU - Norddine, Thomas
AU - Marin, Oana
AU - Benhamadouche, Sofiane
N1 - Funding Information:
This work was supported by the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program of the U.S. Department of Energy (DOE), Office of Nuclear Energy. This research made use of the resources of the High Performance Computing Center at Idaho National Laboratory, which is supported by the Office of Nuclear Energy of the U.S. Department of Energy and the Nuclear Science User Facilities under Contract No. DE-AC07-05ID14517. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725.
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/9
Y1 - 2021/9
N2 - Rod bundle flows are prevalent in nuclear engineering for both light water reactors (LWR) and advanced reactor concepts. Unlike canonical channel flow, the flow in rod bundles presents some unique characteristics, notably due to the inhomogeneous cross section which can present different local conditions of turbulence as well as localized effects characteristic of external flows. Despite the ubiquity of rod-bundle flows and the decades of experimental and numerical knowledge acquired in this field, high-fidelity datasets of multiple-pin configurations are still relatively sparse due to the computational cost involved in generating them at relevant Reynolds numbers. These datasets are of great value as they allow for assessment of the reliability of various turbulence models, as well as allow for a deeper understanding of the flow physics. We present Large Eddy Simulations (LES) of the flow at Reynolds number 19,000 in a square 5 × 5 rod bundle representative of LWR fuel generated by the flow solver Nek5000. We consider standard configurations as well as configurations where the central pin is replaced with a control rod guide thimble, and analyze the flow fields in detail. The accuracy of the LES of the base 5 × 5 configuration is established by comparing against Direct Numerical Simulation (DNS) results. We compare the LES results from Nek5000 with an advanced Reynolds Stress model from STAR-CCM+, which shows good agreement in the wide gaps with larger discrepancies in the narrow gaps. In particular, evidence of gap vortex streets and changes in the turbulence structure are seen in the edge subchannels and in the narrow thimble gaps in LES, but are not predicted by STAR-CCM+.
AB - Rod bundle flows are prevalent in nuclear engineering for both light water reactors (LWR) and advanced reactor concepts. Unlike canonical channel flow, the flow in rod bundles presents some unique characteristics, notably due to the inhomogeneous cross section which can present different local conditions of turbulence as well as localized effects characteristic of external flows. Despite the ubiquity of rod-bundle flows and the decades of experimental and numerical knowledge acquired in this field, high-fidelity datasets of multiple-pin configurations are still relatively sparse due to the computational cost involved in generating them at relevant Reynolds numbers. These datasets are of great value as they allow for assessment of the reliability of various turbulence models, as well as allow for a deeper understanding of the flow physics. We present Large Eddy Simulations (LES) of the flow at Reynolds number 19,000 in a square 5 × 5 rod bundle representative of LWR fuel generated by the flow solver Nek5000. We consider standard configurations as well as configurations where the central pin is replaced with a control rod guide thimble, and analyze the flow fields in detail. The accuracy of the LES of the base 5 × 5 configuration is established by comparing against Direct Numerical Simulation (DNS) results. We compare the LES results from Nek5000 with an advanced Reynolds Stress model from STAR-CCM+, which shows good agreement in the wide gaps with larger discrepancies in the narrow gaps. In particular, evidence of gap vortex streets and changes in the turbulence structure are seen in the edge subchannels and in the narrow thimble gaps in LES, but are not predicted by STAR-CCM+.
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U2 - 10.1016/j.nucengdes.2021.111337
DO - 10.1016/j.nucengdes.2021.111337
M3 - Article
AN - SCOPUS:85109971596
SN - 0029-5493
VL - 381
JO - Nuclear Engineering and Design
JF - Nuclear Engineering and Design
M1 - 111337
ER -