Abstract: Large eddy simulations (LES) for turbulent heat transfer at different molecular Prandtl numbers (Pr=001, 0026, 02, 04, 071) at Re=8 900 in an annulus were performed. Several statistics quantities such as time-mean temperature, temperature fluctuation, turbulent heat flux and turbulent Prandtl number were presented and analyzed. The characteristics of turbulent heat transfer of liquid metal (Pr=001,0026) were compared with those of the traditional fluids (Pr=04,071). The results show that the molecular conduction is the dominant heat transfer mechanism for the liquid metal. The linear law region extends larger while the logarithmic law region becomes shorter and even disappears compared to traditional fluids. With the decrease of Pr, the temperature fluctuation and turbulent heat flux become smaller. Beside, the turbulent Prandtl number of liquid metal is bigger than that of traditional fluids and is very sensitive to its molecular Prandtl number Pr.

Key words: large eddy simulation, liquid metal, low molecular Prandtl number, turbulent heat transfer, turbulent Prandtl number