Advertisement

Turbulence Modelling for CFD-Methods for Containment Flows

Annual Report 06/2010–06/2011
  • Armin Zirkel
  • Eckart Laurien

Abstract

During a severe accident of a light-water reactor, hydrogen can be produced by a chemical reaction between the Zircaloy cladding and water and escape into the containment through a leak in the primary circuit. The prediction of the mass transport of hydrogen is vital for an optimised positioning of countermeasures like recombiners. It is possible that a stable stratification of hydrogen and air occurs, due to the different densities of those fluids. This stratification can be mixed with a free jet. This mixing is characterised by the time dependency of the flow, sharp velocity and density gradients as well as the non-isotropy of Reynolds stresses and turbulent mass fluxes.

With the use of a Reynolds stress turbulence model, the non-isotropic Reynolds stresses can be simulated. A similar approach is theoretically possible for the turbulent mass fluxes, but only the isotropic eddy diffusivity model is currently available in state-of-the-art cfd-software.

The shortcomings of the eddy diffusivity model to simulate the turbulent mass flux are investigated, as well as improvements with the use of a non-isotropic model. Because of the difficulties to get experimental data of flows in real containments, the THAI experimental facility was created to get experimental data for flows in large buildings. The experiments are performed by Becker Technologies. The analysis is using the experimental data of the THAI experiments TH-18, TH-20, TH-21 and TH-22 as the reference case. For safety reasons the used light gas for the TH-20 experiment is helium instead of hydrogen. Due to the rotational symmetry of the geometry as well as the boundary conditions, two-dimensional simulations are performed where applicable. The grids have been built following the best practice guidelines to ensure sufficient grid quality. Several simulations were carried out to investigate the numerical error caused by spatial and time discretisation.

During this reports time frame, simulations of the TH-20 and TH-22 experiments have been performed.

Keywords

Reynolds Stress Reynolds Stress Model Wall Clock Time Reynolds Stress Tensor Helium Concentration 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    H.-J. Allelein, S. Arndt, W. Klein-Hes̈ling, S. Schwarz, C. Spengler and G. Weber: “COCOSYS: Status of development and validation of the German containment code system”, Nuclear Engineering and Design, vol. 238, pp. 872–889, 2008 CrossRefGoogle Scholar
  2. 2.
    H.-J. Allelein, K. Neu and J.P. Van Dorsselaere: “European validation of the integral code ASTEC (EVITA) first experience in validation and plant sequence calculations”, Nuclear Engineering and Design, vol. 235, pp. 285–308, 2005 CrossRefGoogle Scholar
  3. 3.
    I. Kljenak, M. Babic, B. Mavko and I. Bajsic: “Modelling of containment atmosphere mixing and stratification experiment using a CFD approach”, Nuclear Engineering and Design, vol. 236, pp. 1682–1692, 2006 CrossRefGoogle Scholar
  4. 4.
    M. Houkema, N.B. Siccama, J.A. Lycklama and E.M.J. Komen: “Validation of the CFX4 CFD code for containment thermal-hydraulics”, Nuclear Engineering and Design, vol. 238, pp. 590–599, 2008 Google Scholar
  5. 5.
    “International Standard Problem ISP-47 on containment thermal hydraulics final report”, Nuclear Energy Agency, NEA/CSNI/R(2007)10 Google Scholar
  6. 6.
    T. Kanzleiter, A. Kühnel, K. Fischer, M. Heitsch and B. Schramm: “Technical Report THAI Blower Test TH 20”, Report No. 150 1325 TH20, Gesellschaft für Reaktorsicherheit, Köln, 2007 Google Scholar
  7. 7.
    H. Siekmann and P. Thamsen: “Strömungslehre”, vol. 2, Springer, Berlin, 2008 Google Scholar
  8. 8.
    W. Rodi: “Turbulence Models and Their Application in Hydraulics, A State-of-the-art Review”, vol 3, A.A. Balkema, Rotterdam, 1993 Google Scholar
  9. 9.
    D. Wilcox: Turbulence Modelling for CFD, vol. 2, DCW Industries, USA, 2004 Google Scholar
  10. 10.
    W.P. Jones and D. Lentini: “A realisable non-linear eddy viscosity/diffusivity model for confined swirling flows”, International Journal of Heat and Fluid Flow, 2008 Google Scholar
  11. 11.
    F. Menter: “Two-equation eddy-viscosity turbulence models for engineering applications”, AIAA Journal, vol. 32, pp. 1598–1605, 1994 CrossRefGoogle Scholar
  12. 12.
    E. Laurien and T. Wintterle: “On the numerical simulation of flow and heat transfer within the fuel-assembly of the high-performance light-water-reactor”, Proceedings of the KTH-Workshop on Modelling and Measurements of Two-Phase Flows and Heat Transfer in Nuclear Fuel Assemblies, 200l Google Scholar
  13. 13.
    C. Speziale, S. Sarkar and T. Gatski: “Modelling the pressure-strain correlation of turbulence: an invariant dynamical systems approach”, Journal of Fluid Mechanics, vol. 227, pp. 245–272, 1991 CrossRefzbMATHGoogle Scholar
  14. 14.
    ANSYS CFX User Documentation Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  1. 1.Institut für Kernenergetik und EnergiesystemeUniversität StuttgartStuttgartGermany

Personalised recommendations