Analysis of low Reynolds number turbulent flow phenomena in nuclear fuel pin subassemblies of tight lattice configuration

H. Ninokata, Elia Merzari, A. Khakim

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

This paper focuses on the numerical simulation of low Reynolds (Re) number turbulence flow phenomena in tightly packed fuel pin subassemblies and in channels of irregular shape such as eccentric annuli. Highlighted phenomena include (i) turbulence-driven secondary flows inside a subchannel, (ii) local turbulent-laminar transition in the narrow gap region, and (iii) global flow pulsation across the gap along the channel length. These phenomena are simulated by Computational Fluid Dynamics (CFD). The CFD methods employed here are those of Direct Numerical Simulation (DNS) of turbulence, Large Eddy Simulation (LES) and Reynolds-Averaged Navier-Stokes (RANS) equations approach. Complicated turbulent flow structure is due to strong anisotropy in the non-uniform channel geometry that is characterized by wide open channels connected by a narrow gap. The secondary flows in subchannels play an important role in transporting small eddies generated in the wider region toward the narrow gap. Periodic cross-flow oscillations are calculated to appear in the vicinity of the gap region, and the coherent structure is transported in the main flow direction. This macroscopic flow process prevails in the low Re turbulent flow regime and is called as global flow pulsation. Finally a brief discussion is made on their influences onto the mixing between two subchannels that must be taken into account during natural circulation decay heat removals.

Original languageEnglish (US)
Pages (from-to)855-866
Number of pages12
JournalNuclear Engineering and Design
Volume239
Issue number5
DOIs
StatePublished - May 1 2009

Fingerprint

subassemblies
nuclear fuels
low Reynolds number
Nuclear fuels
turbulent flow
Reynolds number
Turbulent flow
Turbulence
Secondary flow
Computational fluid dynamics
configurations
secondary flow
turbulence
computational fluid dynamics
Direct numerical simulation
Large eddy simulation
Flow structure
Navier Stokes equations
Anisotropy
laminar-turbulent transition

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Safety, Risk, Reliability and Quality
  • Waste Management and Disposal
  • Mechanical Engineering

Cite this

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Analysis of low Reynolds number turbulent flow phenomena in nuclear fuel pin subassemblies of tight lattice configuration. / Ninokata, H.; Merzari, Elia; Khakim, A.

In: Nuclear Engineering and Design, Vol. 239, No. 5, 01.05.2009, p. 855-866.

Research output: Contribution to journalArticle

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