G. I. Orosz, S. Tóth, A. Aszódi

29th Symposium of AER on VVER Reactor Physics and Reactor Safety (2019, Energoland, Mochovce NPP, Slovakia)
nuclear applications of computational fluid dynamics (CFD)


Turbulent heat transfer through gas cooled systems is a key factor for the improvements of the Gas cooled Fast Reactors (GFR). Within the FP7 European project THINS (Thermal Hydraulics of Innovative Nuclear Systems), experimental and numerical tools for investigations of the thermal hydraulics of next generation rector systems were developed, applied and validated for innovative coolants. One of the tools is the L-STAR facility, which has been designed and erected at the Karlsruhe Institute of Technology (KIT) to study turbulent flow behaviour and heat transfer enhancement characteristics in gas cooled annular channels under a wide range of conditions. The test section consists of an annular hexagonal cross section channel with an inner electrical heater rod element, placed concentrically within the test section. This design represents the flow domain around a single fuel rod in a future GFR.
In this paper simulation results for the fluid flow at uniform heat release conditions for the smooth heater rod are presented. Application of the facility allows using various values of heating power of the heated rod and fluid mass flow depending on the chosen scenario. The purpose of this study is to create CFD (Computational Fluid Dynamics) models for the L-STAR that are capable of reproducing the results of reference measurements.
The calculations were carried out with ANSYS CFX 17 code. All simulations were performed as steady-state calculations. Mesh, structural element and turbulence model sensitivity studies were also performed during this work. With these model results it becomes possible to validate other CFD models to be applied for the ALLEGRO experimental gas cooled reactor fuel assemblies.

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