Controlling turbulence in tight rod bundles

Elia Merzari, Paul Fischer

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


The flow in rod bundles is of key importance in a variety of engineering fields. It is representative, for instance, of the flow in a nuclear reactor core and the flow in a tube and shell heat exchanger. For particularly tight rod bundles (pitch to diameter ratio lower than 1.1 in hexagonal arrays) the flow is subject to a Kelvin-Helmholtz instability that is present in both laminar and turbulent flows and is likely to influence transition. Such instability has been proven to exist in bare bundles and even in bundles containing spacing devices. In fact, rod bundles are typically separated by devices designed to keep the rods (or tubes) in place and avoid vibrations. Simple spacer designs, such as honeycomb arrays with dimples, do not remove the instability. The present paper discusses a procedure to investigate the effect of spacing devices have on the most unstable mode of turbulence. A linear stability analysis of the laminar flow for several spacing device configurations has been performed by using adjoint methods. The results show the effect of the spacing on the formation of large scale coherent structures and help lay the ground for a theory of turbulence control in tight rod bundles.

Original languageEnglish (US)
Title of host publicationASME 2013 Fluids Engineering Division Summer Meeting, FEDSM 2013
StatePublished - 2013
Externally publishedYes
EventASME 2013 Fluids Engineering Division Summer Meeting, FEDSM 2013 - Incline Village, NV, United States
Duration: Jul 7 2013Jul 11 2013

Publication series

NameAmerican Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM
Volume1 B
ISSN (Print)0888-8116


OtherASME 2013 Fluids Engineering Division Summer Meeting, FEDSM 2013
Country/TerritoryUnited States
CityIncline Village, NV

ASJC Scopus subject areas

  • Mechanical Engineering


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