Thermal convection studies in liquid metal flow inside a horizontal duct under the influence of transverse magnetic field

Abstract

An experiment is conducted to study the effect of magnetic field on heat transfer in a magnetohydrodynamic flow of molten lead–lithium, in a stainless steel thin-wall duct, with a uniform surface heat flux at its bottom wall. A novel technique of measuring fluid temperature inside the duct is applied to map the temperature profile in a flow cross section, at both ends of the heated section, using a 4 × 4 array of 16 equidistantly placed thermocouples. Surface temperature, as well as electric potential, is measured at seven different locations along the heated section. Based on the temperature profiles obtained at the outlet of the heated section, various flow regimes have been identified over the experimentally investigated flow parameters. Distinctively, three flow regimes have been recognized depending on the dominance of buoyancy force, electromagnetic force, and inertial force. In order to better understand the experimental data, numerical simulations are performed using COMSOL. In the buoyancy force dominated flow regime, a quasi-two-dimensional turbulence flow is predominant, determining the overall heat transfer mechanism. In the electromagnetic force dominated regime, the perturbation due to buoyancy force is suppressed by the magnetic field. Finally, in the inertial force dominated regime, the electromagnetic force and buoyancy force do not play a significant role in determining the heat transfer mechanism. The transition between observed flow regimes has been identified in terms of Grashof, Reynolds, and Hartmann numbers, and the Nusselt number has been calculated for quantitative comparison of heat transfer in these flow regimes.