Simulation of turbulent flow and heat transfer in channels between rod bundles

The turbulent flow and heat transfer in triangular rod bundles are investigated theoretically with CFD code FLUENT. The unsteady Reynolds Stress Model is adopted as turbulence modeling. The wall function is used for near wall boundary layer. The calculation results were in agreement with experimental data. The effects of the Reynolds number and pitch to diameter ratio on the flow and heat transfer in the lattice are significant. The traditional theoretical models could not predict the flow and heat transfer in the lattice. The P/D = 1.03 is a critical point. In this case, the flow and heat transfer in the lattice is the most desirable and most efficient, and the nuclear power could also reach its maximum. The variation of large scale coherent structure with pitch to diameter ratio is consistent with the variation of the Nusselt number with pitch to diameter ratio.