Measurements of frequencies and spatial correlations of coherent structures in rod bundle flows

Baratto, F.; Bailey, Sean; Tavoularis, Stavros

doi:10.1016/j.nucengdes.2005.12.009

Cited by 42 publications

(9 citation statements)

References 13 publications

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“…In the case of a tightly packed rod bundle, which contains multiple interconnected subchannels, the individual vortex streets that would form near each narrow gap would be coupled and would form a rod bundle vortex network (Tavoularis 2011). Experimental studies of cross-gap flows in rod bundles include those by Rowe, Johnson & Knudsen (1974), Hooper & Rehme (1984), Möller (1991), Krauss & Meyer (1996), Krauss & Meyer (1998), Baratto, Bailey & Tavoularis (2006) and Silin, Masson & Rauschert (2008). Most of the published literature on the topic of cross-flows in gaps is concerned with relatively large Reynolds number flows, in which the flow is fully turbulent (Wu & Trupp 1993;Meyer & Rehme 1994;Guellouz & Tavoularis 2000a,b).…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of flow development and gap vortex street in an eccentric annular channel. Part 1. Overview of the flow structure

Choueiri

Tavoularis

2014

J. Fluid Mech.

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Flow visualization, laser Doppler velocimetry and planar and stereoscopic particle image velocimetry were used to investigate the isothermal velocity field along an eccentric annular channel with a diameter ratio of 0.5 and an eccentricity of 0.8 for a Reynolds number of 7300. Observation of the flow development has identified three distinct regions: the entrance region, the fluctuation-growth (FG) region and the rapid-mixing (RM) region. Weak quasi-periodic velocity fluctuations were first detected in the downstream part of the entrance region, and grew into very strong ones, reaching peak-to-peak amplitudes in the narrow gap that were nearly 60 % of the bulk velocity. Two mixing layers were identified on either side of the gap, which generated a street of counter rotating vortices and thorough large-scale mixing of the fluid in the channel.

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Section: Introductionmentioning

confidence: 99%

Experimental investigation of flow development and gap vortex street in an eccentric annular channel. Part 1. Overview of the flow structure

Choueiri

Tavoularis

2014

J. Fluid Mech.

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“…Experimental research has, among others, been executed by Hooper and Rehme (1984), Meyer and Rehme (1994) and Tavoularis (2014, 2015) on a more fundamental level using simple geometries. A more complex geometry, a 5-rod model of a 37-rod CANDU reactor, was investigated by Baratto et al (2006).…”

Section: Introductionmentioning

confidence: 99%

“…Since a network of gaps and subchannels is present in a rod bundle, multiple vortex streets are present. This leads to a more chaotic and complex behaviour of the pulsating flow, showing strong correlation between the different gap vortex streets (Baratto et al, 2006), which suggests more complex simulations are necessary. This was addressed in the work of Chang and Tavoularis (2007).…”

Section: Introductionmentioning

confidence: 99%

Vibrations in a 7-rod bundle subject to axial flow: Simulations and experiments

Dolfen

Bertocchi

Rohde

et al. 2019

Nuclear Engineering and Design

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Being able to quantify mechanical vibrations is of key importance for the safety of nuclear power plants, as they are able to induce damage. In this work, numerical simulations are used to compute water flow and vibration in a densely packed bundle of 7 rods, mimicking an experimental setup. This flow configuration is chosen to resemble the coolant flow through a nuclear reactor core. Because of the wall proximity, a considerable velocity difference between the narrow gaps and the subchannels exists, with an inflection point in the velocity profile. This yields an unstable situation, and large vortices are continuously created through a mechanism similar to the Kelvin-Helmholtz instability. The vortex streets in between the rods are associated with a fluctuating pressure field, causing vibrations of the rods. The experimental setup contains 7 steel cylinders, encased in a hexagonal duct. The central rod contains a section where the steel is replaced by a water-filled silicone tube, clamped at both extremes to the steel rod, and the vibrations of this section are examined. The numerical approach consists of coupled fluid-structure interaction (FSI) simulations, with the flow being modelled using computational fluid dynamics (CFD) and the structure using computational solid mechanics (CSM). The available experimental data consist of Laser Doppler Anemometry (LDA) measurements and high-speed camera footage of the wall movement of the silicone rod. Equivalent data is collected from the numerical simulations. The simulations are repeated for different flow rates. The frequency spectrum of the coherent structures, and the frequency and amplitude of the wall movement are compared for each operating point, as well as their trend as a function of the flow rate. The dominant frequencies found in the simulation results were similar to the experimental results, although slightly higher. They also showed a linear trend, just like the experiments. A larger mismatch was present for the structural response, the frequencies found using the FSI model being more than twice as high.

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“…Krauss and Meyer (1998) measured the three instantaneous velocity components and the instantaneous temperature in the turbulent air flow in a bare 37-rod bundle with the hot-wire anemometry and obtained all components of Reynolds stresses and turbulent heat fluxes. Baratto et al (2006) measured the turbulence quantities in the air flow through a 5 rod bundle installed in a quasi-trapezoidal duct. Lee et al (2013) investigated the effect of gap width on the flow pulsation and turbulent mixing using particle image velocimetry (PIV).…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on anisotropic turbulent flow in a 6×6 rod bundle with LDV

Xiong

et al. 2014

Nuclear Engineering and Design

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Measurements of frequencies and spatial correlations of coherent structures in rod bundle flows

Cited by 42 publications

References 13 publications

Experimental investigation of flow development and gap vortex street in an eccentric annular channel. Part 1. Overview of the flow structure

Experimental investigation of flow development and gap vortex street in an eccentric annular channel. Part 1. Overview of the flow structure

Vibrations in a 7-rod bundle subject to axial flow: Simulations and experiments

Experimental investigation on anisotropic turbulent flow in a 6×6 rod bundle with LDV

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