Numerical simulation of the effect of centrifugal buoyancy on the turbulent mixed convection heat transfer

In order to investigate the influence of centrifugal buoyancy on the fluid flow and heat transfer in rotary machinery, studies have been carried out for a rotary radially outward developed turbulent flow by using direct numerical simulation (DNS) method. The turbulent Reynolds number, rotation number and Prandtl number of the flow are kept at 300, 1.5, 0.71, respectively, then simulations and analysis are conducted for characteristics of flow and heat transfer with Grashof number equal to 0, 9 000, 20 000, and 50 000, respectively. The results indicate that the mainstream velocity, temperature and secondary flow all increase with the centrifugal buoyancy forces. The maximum mainstream velocity and the minimum temperature appear in the side of the unstable wall. With the increase of centrifugal buoyancy forces, the velocity fluctuation is strengthened; the temperature fluctuation increases firstly then decreases in the side of the unstable wall, however it decreases firstly then increases in the side of the stable wall; the heat transfer performance on the stable wall is enhanced and becomes better firstly then worse on the unstable wall.