International Scientific Journal

Thermal Science - Online First

Authors of this Paper

External Links

online first only

CFD simulation of swirl flow in hexagonal rod bundle geometry by split mixing vane grid spacers

Heat transfer and pressure drop are numerically investigated for turbulent flows through a hexagonal fuel rod bundle. For the purpose of numerical analysis, the geometric and boundary conditions were taken from the VVER-1000. Since VVER-1000 does not have mixing vane on the grid spacer of the fuel assembly, Split mixing vane is designed to boost turbulent flow and heat transfer in the rod bundle subchannels. The computational domain including two grid spacers extend from 100×Dh upstream of the first grid spacer to 250×Dh downstream of the second grid spacer. The steady state form of the Reynolds-averaged Navier-Stokes (RANS), mass, energy and turbulence equations was discretized and solved using Ansys-CFX. The standard k-epsilon model is employed to simulate turbulence. The results show a considerable increase in the average heat transfer to ~10×Dh downstream of the grid spacer using the mixing vane on the grid spacer of VVER type reactor. As expected, the pressure loss through the grid spacer also increased slightly with the mixing vanes.
PAPER REVISED: 2018-01-31
PAPER ACCEPTED: 2018-02-03
  1. Rehme, K., Pressure Drop Correlations for Fuel Element Spacers, Nuclear Technology, 17 (1973), 1, pp.15-23.
  2. Rehme, K., Pressure Drop of Spacer Grids in Smooth and Roughened Rod Bundles, Nuclear Technology, 33 (1977), 3, pp. 314-317.
  3. Rehme, K. Trippe, G., Pressure Drop and Velocity Distribution in Rod Bundles with Spacer Grids, Nuclear Engineering and Design, 62 (1980), 1-3, pp. 349-359.
  4. Bragina, V.L., et al., Experimental Study of Enhancement of Heat Transfer From a Tube Bundle in Turbulent Axial Flow, Heat transfer: Soviet research, 13 (1981), 4, pp. 14-18.
  5. Yao, S.C., et al., Heat Transfer Augmentation in Rod Bundle Near Grid Spacers, Journal of Heat Transfer, 104 (1982), pp. 76-81.
  6. Chesna, B.A., Kolesnikovas, I.Y., Influence of Spacer Grids on the Rate of Heat Transfer in an Air Stream Flowing Longitudinally Through a Bundle of Rods, International Chemical Engineering, 27 (1987), 1, pp. 158-161.
  7. Cigarini M., Dalle Donne M., Thermohydraulic Optimization of Homogeneous and Heterogeneous Advanced Pressurized Reactors, Nuclear Technology, 80 (1988), pp. 107-132.
  8. In, W.K., et al., Flow Analysis for Optimum Design of Mixing Vane in a PWR Fuel Assembly, Journal of the Korean Nuclear Society, 33 (2001), 3, 327.
  9. Kim, K.Y., Seo, J.W., Shape Optimization of a Mixing Vane in Subchannel of Nuclear Reactor, Journal of Nuclear Science and Technology, 41(2004), 5, pp. 641-644.
  10. Ikeda, K., et al., Single-phase CFD Applicability for Estimating Fluid Hot-Spot Locations in a 5 × 5 Fuel Rod Bundle, Nuclear Engeering Design, 236 (2006), 1149-1154.
  11. Ikeno, T., et al., The Effect of Mixing Vane Arrangements in a Subchannel Turbulent Flow, Journal of Nuclear Science and Technology, 43 (2006), 10, 1194-1205.
  12. Song, K.N., et al., Performance Evaluation of New Spacer Grid Shapes for PWRs, Journal of the Korean Nuclear Society, 39 (2007), 6, 737-347.
  13. Nematollahi, M.R., Nazifi, M., Enhancement of Heat Transfer in a Typical Pressurized Water Reactor by Different Mixing Vanes on Spacer Grids, Energy Conversion Management, 49 (2008), 1981-1988.
  14. Schikorr M., et al., Proposal for Pressure Drop Prediction for a Fuel Bundle with Grid Spacers using Rehme Pressure Drop Correlations, Nuclear Engineering Design, 240 (2010), 7, 1830-1842.
  15. Ganjiani, H., Firoozabadi, B., Three-dimensional Simulation of Turbulent Flow in 3-sub Channels of a VVER-1000 Reactor, Sharif University of Technology Transaction B: Mechanical Engineering, 17 (2010), 2, 83-92.
  16. Tóth, S., Aszódi, A., CFD Analysis of Flow Field in a Triangular Rod Bundle, Nuclear Engineering Design, 240 (2010), 2, 352-363.
  17. Tóth, S., Aszódi, A., CFD Study on Coolant Mixing in VVER-440 Fuel Rod Bundles and Fuel Assembly Heads, Nuclear Engineering Design, 240 (2010), 9, 2194-2205.
  18. Navarro, M.A., Santos, A.C., Evaluation of a Numeric Procedure for Flow Simulation of a 5 × 5 PWR Rod Bundle with a Mixing Vane Spacer, Progress of Nuclear Energy, 53 (2011), pp. 1190-1196.
  19. Sang-Ki, M., et al., Single-phase Convective Heat Transfer Enhancement by Spacer Grids in a Rod Bundle, Journal of Nuclear Science and Technology, 51 (2014), 4, 543-557.
  20. Chang, S.K., et al., Turbulent Mixing in a Rod Bundle with Vaned Spacer Grids: OECD/NEA-KAERI CFD Benchmark Exercise Test, Nuclear Engineering and Design, 279 (2014), pp.19-36.
  21. Lee, J.R., et al., Synthesis of the Turbulent Mixing in a Rod Bundle with Vaned Spacer Grids Based on the OECD-KAERI CFD Benchmark Exercise, Nuclear Engineering and Design, 279 (2014), pp.3-1.
  22. Cinosi, N., et al., CFD Simulation of Turbulent Flow in a Rod Bundle with Spacer Grids (MATIS-H) using STAR-CCM+, Nuclear Engineering and Design, 279 (2014), pp.37-49.
  23. Bieder, U., et al., LES Analysis of the Flow in a Simplified PWR Assembly with Mixing Grid, Progress in Nuclear Energy, 75 (2014), pp.15-24.
  24. In, W.K., et al., Measurement and CFD Calculation of Spacer Loss Coefficient for a Tight-Lattice Fuel Bundle, Nuclear Engineering and Design, 284 (2015), pp.153-161.
  25. Lee, et al., Augmentation of Single-phase Forced Convection Heat Transfer in Tightly Arrayed Rod Bundle with Twist-Vane Spacer Grid, Experimental Thermal and Fluid Science, 76 (2016), 185-192.
  26. Hutli, E., et al., Experimental Approach to Investigate the Dynamics of Mixing Coolant Flow in Complex Geometry using PIV and PLIF Techniques. Thermal Science, 19 (2015), pp.989-1004.
  27. Qin, S., et al., Experimental Investigation on Repeatability of CHF in Rod bundle with non-uniform Axial Heat Flux Distribution, Progress in Nuclear Energy, 90 (2016), pp.151-154.
  28. Mao, H., et al., Modeling of Spacer Grid Mixing Effects through Mixing Vane Crossflow Model in Subchannel Analysis, Nuclear Engineering and Design, 320 (2017), 141-152.
  29. Chen, X., et al., Validation of CFD Analysis for Rod Bundle Flow Test with Vaned Spacer Grids., Annals of Nuclear Energy, 109 (2017): 370-379.
  30. Shashi Kant, V. et al., Experimental Investigation of Effect of Spacer on Single Phase Turbulent Mixing Rate on Simulated Subchannel of Advanced Heavy Water Reactor, Annals of Nuclear Energy, 110 (2017), pp. 186-195.
  31. Wu, J. M. , et al., CFD Analysis of the Impact of a Novel Spacer Grid with Longitudinal Vortex Generators on the Sub-Channel Flow and Heat Transfer of a Rod Bundle, Nuclear Engineering and Design, 324 (2017), 78-92.
  32. Launder, B.E., Spalding, D.B., The Numerical Computation of Turbulent Flows, Computer Methods in Applied Mechanics and Engineering, 3 (1974), 269-289.