Toward High Fidelity LES Simulations of 5 x 5 PWR Fuel Bundle with Mixing Vane

Journal Article · Sat Jul 01 04:00:00 EDT 2017 · Transactions of the American Nuclear Society

OSTI ID:23050420

Sarikurt, Fatih S.; Busco, Giacomo; Hassan, Yassin A. ^[1]

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1. Texas A and M University, 3133 TAMU, College Station, TX, 77843-3133 (United States)

The present work illustrates one example of a computational fluid dynamics (CFD) application in the nuclear engineering field. Since CFD is one of the most powerful tools available at the actual state of the art that could in principle help and assist the design process, a compromise should be established between the accuracy of the CFD numerical model (RANS - LES - DNS) and the computational cost of the simulations. In this spirit, this work will present the computational results from two different CFD model categories, Large Eddy Simulations (LES) and Reynolds-averaged Navier-Stokes (RANS) models. Both treat the flow turbulence issue in two separate ways, which differ mostly in the resolution of the turbulence statistics and the computational cost. The single-phase hydraulic problem presented involves the steady-state turbulent flow field modelling and resolution around a scaled PWR mixing vane grid, designed by Westinghouse and tested by Texas A and M University. The role of the mixing vane/spacer grid is to enhance the turbulent mixing and hence heat transfer of the core coolant around fuel bundles, thus increasing the departure of nucleate boiling-critical heat flux (DNB-CHF) point, as well as important structural functions for the rods bundles. The authors numerically studied the flow field characteristics at the region downstream of the spacer grids and validated their results to particle imagery velocimetry (PIV) measurements. Dominguez and Hassan performed two-dimensional time resolved PIV (TR-PIV) measurements within a 5 x 5 PWR rod bundle with spacer-grids that utilized a matching index of refraction (MIR) approach. Their averaged data showed a rather uniform direction velocity profile after the spacer grid while the downstream illustrated a no slip wall profile. The available PIV flow field experimental results from Texas A and M show complex structures of the flow field downstream the mixing vanes with the formation of secondary flows that tend to enhance the turbulent heat transfer, due to the mixing vanes geometry itself. Computational results will be validated with the available experimental data.

• OSTI ID: 23050420
• Journal Information: Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 116; ISSN 0003-018X
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
42 ENGINEERING
97 MATHEMATICS AND COMPUTING
COOLANTS
CRITICAL HEAT FLUX
DEPARTURE NUCLEATE BOILING
FUEL ELEMENT CLUSTERS
GEOMETRY
HEAT TRANSFER
HYDRAULICS
LARGE-EDDY SIMULATION
NAVIER-STOKES EQUATIONS
NUCLEAR ENGINEERING
NUCLEAR INDUSTRY
PWR TYPE REACTORS
REFRACTIVE INDEX
REYNOLDS NUMBER
SPACERS
STEADY-STATE CONDITIONS
TIME RESOLUTION
TURBULENT FLOW