PARAMETRIC STUDY ON LAMINAR-TURBULENT TRANSITION IN SQUARE ROD BUNDLES

Luiz C. Aldeia Machado, Carolina S.B. Dutra, Sean P. Bistany, Elia Merzari

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

During the lifetime of a nuclear reactor, the coolant inside the pressure vessel can experience different flow regimes. Laminar and turbulent flow regimes are widely studied and have several models that can be applied. However, the mechanism of laminar-turbulent transition is less well understood. Understanding such transition is crucial since it can be essential during transients such as reactor startup or accidents. It can also play an important role in advanced reactors that operate at low flow conditions. In this work, we perform a parametric numerical study to identify how the Reynolds Number (Re), Pitch-to-diameter ratio (P/D), and domain length (L) affect the laminar-turbulent transition region. We focus on squared array rod bundles. The simulations are carried out using the spectral-element code NekRS and a Direct Numerical Simulation (DNS) approach [1, 2]. We imposed a no-slip condition on the walls. The P/D ranged from 1.05 to 1.20, while the Re varied from 250 to 3500. We analyze the temporal and spatial behavior of the instabilities as a function of P/D and (Re) in detail, including the Power Spectral Density (PSD) method [3].

Original languageEnglish (US)
Title of host publicationProceedings of the 30th International Conference on Nuclear Engineering "Nuclear, Thermal, and Renewables
Subtitle of host publicationUnited to Provide Carbon Neutral Power", ICONE 2023
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Print)9784888982566
StatePublished - 2023
Event30th International Conference on Nuclear Engineering, ICONE 2023 - Kyoto, Japan
Duration: May 21 2023May 26 2023

Publication series

NameInternational Conference on Nuclear Engineering, Proceedings, ICONE
Volume2023-May

Conference

Conference30th International Conference on Nuclear Engineering, ICONE 2023
Country/TerritoryJapan
CityKyoto
Period5/21/235/26/23

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering

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