Numerical simulation of MHD effects on convective heat transfer characteristics of flow of liquid metal in annular tube

A numerical study is conducted in an annular duct formed by a SS316 circular tube with electrically conducting walls and a coaxial heater pin, with liquid Lithium as the working fluid for magnetic field ranging from 0 to 1 T. The Hartmann and Stuart number of the study ranges from 0 to 700 and 0 to 50 respectively. The Reynolds number of the study is 104. shown that the convective heat transfer and hence the Nusselt number decreases near the walls perpendicular to the magnetic field due to reduction in turbulent fluctuations with increase of magnetic field. It was observed that the Nusselt number value increases near the walls parallel to the magnetic field as the mean velocity increase near the walls. A singular rise was observed near both the walls near Stuart number ∼10 which is due to the increase of turbulence levels in the process of changing from turbulent to electromagnetically laminarized flow. very low Reynolds number ∼300 is used, the reduction in Nusselt number near the perpendicular walls is less. This shows that the reduction in Nusselt number near the perpendicular walls for the high Reynolds number study is due to the reduction in turbulent fluctuations. The Nusselt number was found to increase near the parallel walls as the mean velocity increases near the walls. n insulating duct is used the Nusselt number near the parallel walls did not increase for the case with insulating walls as in the case with conducting walls showing the contribution of the ‘M’ shaped velocity profile in the Nusselt number increase near the parallel walls. The Nusselt number near the perpendicular walls was found to decrease at a higher rate in case of insulating walls than that of the study with conducting walls.