A Turbulence Model Sensitivity Analysis on the Hydraulic Behavior in the Inlet Plenum of the Proposed NIST Neutron Source Design
Abdullah Weiss, Joy Shen, Anil Gurgen
The NIST Neutron Source, or NNS, is a proposed reactor designed to eventually replace the aging National Bureau of Standards Reactor at the NIST Center for Neutron Research (NCNR). The NNS is a light water moderated and cooled, compact reactor used to provide a reliable flux of cold and thermal neutrons for various neutron scattering and irradiation experiments. The reactor will be fueled with U-10Mo LEU curved plates, yielding flow channels that resemble those in other research reactors with plate-type fuels. This work focuses on assessing the flow behavior in the inlet plenum leading into the flow channels cooling the fuel plates, where a 2-dimensional representation of the inlet plenum is modeled using OpenFOAM®. The inlet plenum has a geometry that induces complex phenomena where the flow gets separated, then mixed, then separated again within a very short lead-in to the fuel plates, which necessitates the use of computational fluid dynamics or CFD models for further analyses. The geometry and mesh are discussed, and multiple Reynolds-Averaged Navier Stokes (RANS) models are investigated and compared including the standard k-ϵ, standard k-ω, k-ω SST, realizable k-ϵ, and Spalart-Allmaras models. The resulting pressure and velocity distributions at the inlet of the fuel channels are computed for each of the RANS models, where the sensitivity of the results to variations in the models is discussed in detail. Comparisons to canonical flows from literature are made where appropriate to provide an insight on the validity of each model.
August 20-25, 2023
Washington, DC, DC, US
20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20)
, Shen, J.
and Gurgen, A.
A Turbulence Model Sensitivity Analysis on the Hydraulic Behavior in the Inlet Plenum of the Proposed NIST Neutron Source Design, 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20), Washington, DC, DC, US, [online], https://doi.org/10.13182/NURETH20-40168, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=936264
(Accessed March 5, 2024)