| Liquid metal has used as coolant in fast reactor and accelerator driven system (ADS). This paper will mainly focus on the turbulent heat transfer of liquid metal. In order to obtain the turbulent statistics quantities such as time-mean temperature, temperature fluctuation, turbulent heat flux and turbulent Prandtl number, Large Eddy Simulation (LES) for liquid metal in an annulus is performed. Compared with the turbulent heat transfer of traditional fluid (the molecular Prandtl number will be Pr=1.0and Pr=0.4in this paper), the turbulent heat transfer of liquid metal is studied.Due to the low molecular Prandtl number of liquid metal, the molecular conduction is dominat heat transfer mechanism for the heat transfer of liquid metal flow and the turbulent heat transfer is small. And the linear law region extend in the dimensionless temperature profile, while the logarithmic law region disappears. Compared with traditional fluid, the temperature fluctuation and turbulent heat flux become smaller and flatten. With the decreasing Reynolds number in the turbulent heat transfer of liquid metal, the linear law region of dimensionless temperature will be extended and the temperature fluctuation will be smaller while the peak’s location of the temperature fluctuation is invariant. Besides, with the decreasing Reynolds number, the turbulent heat transfer of liquid metal will become smaller and flatten.The turbulent Prandtl number of traditional fluid arounds1. However, the turbulent Prandtl number of liquid metal is very different with that of traditional fluid. The turbulent Prandtl number of liquid metal is bigger than1, and it’s very sensitive to the change of the molecular Prandtl number, with the decreasing Pec let number, the turbulent Prandtl number of liquid metal become bigger. Also, the turbulent Prandtl number of liquid metal is dependent on the ratio of annulus. With the decreasing Peclet number, the Nusselt number of liquid metal in an annulus will become smaller.Based on the LES data, this paper will present the effect of the Reynolds Averaged Navier-Stokes (RANS) on the simulation of turbulent heat transfer for liquid metal. Among the four turbulent models, the prediction of the standard k-ω model on the turbulent heat transfer of liquid metal is realtively accuracy. The turbulent Prandtl number which is adopted in the RANS simulation, has a significant effects on the result of RANS simulation. There are some errors when the turbulent Prandtl number Prt=1.0and the Kay’s turbulent Prandtl model are applied in the RANS modelling the turbulent heat transfer of liquid metal in an annulus. And new turbulent Prandtl number is necessary. |
