Investigation of Thermal Turbulent Flow Characteristics of Wire wrapped Fuel Pin Bundle of Sodium Cooled Fast Reactor in Lattice-Boltzmann Framework

In the presented study, thermal turbulent flow simulations of fuel pin bundles with helical spacer wires have been carried out. The lattice-Boltzmann method (LBM) is used for both fluid flow and heat transfer calculations. Hence, WALE and VLES turbulence models are implemented to the open-source LBM code and are coupled with the heat transfer modules. A 7-pin bundle geometry, flow and uniform heat flux conditions of Indian Prototype Fast Breeder Reactor (PFBR) are selected for the simulation purposes. The simulations are handled for hexagonal fuel rod bundle with two-helical-pitch-length geometry. The post processed quantities such as velocity and temperature profiles and Reynolds stresses are compared for WALE and VLES turbulence models. Additionally, the Nusselt number and friction factor obtained from WALE and VLES are compared with the experimental correlations. The comparisons show that LBM simulations are in good agreement with the experimental data. Under the coarse (for WALE simulations) Dh/50 lattice resolution, VLES model gives relatively better results. In this study, it is also pointed out that LBM can be used for the complex fast breeder reactor coolant geometry and thermal turbulent flow conditions.