Interaction of a light gas stratified layer with an air jet coming from below: Large scale experiments and scaling issues

Studer, Etienne; Brinster, J.; Tkatschenko, I.; Mignot, Guillaume; Paladino, Domenico; Andreani, Michele

doi:10.1016/j.nucengdes.2012.10.009

Cited by 48 publications

(19 citation statements)

References 13 publications

(10 reference statements)

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“…These jet behaviors are qualitatively the same as that observed in the previous study [13]. However, there is a clear difference between the velocity field of the LES and RANS analysis without the turbulence model modification.…”

supporting

confidence: 86%

A Study on Improvement of RANS Analysis for Erosion of Density Stratified Layer of Multicomponent Gas by Buoyant Jet in a Containment Vessel

Abe¹,

Ishigaki²,

Sibamoto³

et al. 2015

JEPE

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Abstract:The analysis on a density stratification layer consisting of multiple gases in the reactor containment vessel is important for the safety assessment of sever accidents. The JAEA (Japan Atomic Energy Agency) has started the project on the containment thermal hydraulics. We carried out CFD (computational fluid dynamics) analyses in order to investigate the erosion of the density stratification layer by a vertical buoyant jet under this project. We used the RANS (Reynolds averaged numerical simulation) and LES (large eddy simulation) models to analyze the erosion of a density stratification layer by a vertical buoyant jet in a small vessel which represents a containment vessel. This numerical study calculates the turbulent mixing of a two-component (air and helium) gas mixture. The turbulence models used for the RANS analyses are two types of k-ε models. The first model is the low Reynolds number k-ε model developed by Launder and Sharma. The second model is modified from the first model in order to accurately consider the turbulent production and damping in a stratification layer. The results indicated while the erosion rate calculated by the low-Re k-ε model was much faster than that of the LES model, the modified k-ε model could calculate the erosion rate similar to the LES result.

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supporting

confidence: 86%

A Study on Improvement of RANS Analysis for Erosion of Density Stratified Layer of Multicomponent Gas by Buoyant Jet in a Containment Vessel

Abe¹,

Ishigaki²,

Sibamoto³

et al. 2015

JEPE

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“…17 represents the time interval modeled in the present study. Further details of the experimental conditions and performed measurements can be found elsewhere (Studer et al, 2012;Brinster et al, 2011).…”

Section: Lowma-3 Mistra Resultsmentioning

confidence: 99%

“…Depending on the Froude number, Fr, the stratified layer can stay intact for Fr < 1, be partly eroded for Fr ∼ 1 and become well mixed for Fr > 1-see Studer et al (2012) for discussion. Fig.…”

Section: Stratified Layer Erosion Phenomenonmentioning

confidence: 99%

Turbulent jet erosion of a stably stratified gas layer in a nuclear reactor test containment

Ishay

Bieder

Ziskind

et al. 2015

Nuclear Engineering and Design

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“…The applicability of the algebraic model, k‐ε model, and SST k ‐ ω model to both the build‐up of stratification and the erosion process is evaluated, compared to experimental results. With SST k ‐ ω model, effects of the location of gradient layer and steam flow rate are analyzed, which correspond to the analytical results from the model of interaction Froude number, which is proposed by Studer et al…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on erosion of hydrogen stratification by steam jet within a local compartment

2020

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Summary During hypothetical severe accidents in nuclear power plants, a large amount of hydrogen is generated rapidly as a result of zirconium‐water reaction and released into local compartments. Deflagration or detonation risk is probably caused by the uneven hydrogen distribution. Generally, buoyancy drives light combustible gas up to establish gas stratification. On the other hand, stratification may be destroyed by convection flow from steam injection due to coolant's discharge from the primary loop. The mechanism of erosion of stratification can be divided into buoyancy dominated and momentum dominated regimes, the priority of which depends on a nondimensional parameter, named of interaction Froude number. However, jet velocity and the diameter on the interface between steam and stratification are difficult to measure in experiments. Therefore, CFD method is adopted to capture a detailed velocity profile to solve this problem. In this article, a CFD model of single local compartment facility is built and helium distribution behavior within the local compartment is fully investigated, as a substitute of hydrogen, which is usually used in experiments. Prior to determining the interaction Froude number, four flow models, including laminar flow model, algebraic model, k‐ε turbulence model and shear stress transport (SST) k‐ω model are evaluated under three typical experimental stages, including light gas injection, the formation of stratification, and the erosion of stratification. Results show that SST k‐ω model can predict much better under these specific conditions in the small‐scaled configuration, compared to the experimental results. Next, with the setup of a helium stratification structure with homogeneous layer and gradient layer, the interaction between steam and gradient layer is analyzed in detail. The mechanisms of erosion of stratification can be divided into complete penetration, destruction from the bottom level to the top and soft dissolution without penetration, corresponding to the interaction Froude numbers of being greater than 1, close to 1, and far less than 1. The simulation results are consistent with relevant literature findings. The present work can help studying the complex hydrogen distribution process in local compartment and provide data for evaluation of postinerting strategy in severe accident management.

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Interaction of a light gas stratified layer with an air jet coming from below: Large scale experiments and scaling issues

Cited by 48 publications

References 13 publications

A Study on Improvement of RANS Analysis for Erosion of Density Stratified Layer of Multicomponent Gas by Buoyant Jet in a Containment Vessel

A Study on Improvement of RANS Analysis for Erosion of Density Stratified Layer of Multicomponent Gas by Buoyant Jet in a Containment Vessel

Turbulent jet erosion of a stably stratified gas layer in a nuclear reactor test containment

Numerical investigation on erosion of hydrogen stratification by steam jet within a local compartment

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