SELECTION OF AN APPROPRIATE TURBULENCE MODEL TO EVALUATE PERFORMANCES OF NOVEL FUEL GEOMETRIES FOR THE 'IRIS' REACTOR

摘要

A comparative study of different turbulence models is presented to select the most appropriate one for the evaluation of thermo-hydrai;ic performances of innovative core designs. The standard k-ε and different, linear and non linear, low Reynolds k-ε models are applied to fully developed flow in a triangular lattice rod bundle. Shear stresses and velocity distributions are evaluated using the commercial code Star-CD. The relative performance of the models is assessed indicating different predictions between linear and non linear turbulence closures. The results show that the capability of non linear models to account for anisotropic effects leads to better performances in modeling turbulent flow in tight lattice rod bundles. This capability is clearly shown by the existence of a secondary flow field in the plane normal to the flow direction.