HEAT-TRANSFER IN LAMINAR AND TURBULENT LIQUID-METAL MHD FLOWS IN SQUARE DUCTS WITH THIN CONDUCTING OR INSULATING WALLS

The heat transfer in fully-developed liquid-metal flows in a square du ct with a uniform, transverse magnetic field is analyzed. Velocity pro files obtained for laminar; and turbulent regimes [Cuevas, S., Picolog lou, B. F., Walker, J. S. and Talmage, G., Int. J. Engng Sci, 1997, 35 , 485] are employed to solve the heat transfer equation through finite differences, in a duct with one side wall (parallel to the magnetic f ield) uniformly heated and three adiabatic walls. Turbulent effects ar e introduced through eddy viscous and thermal diffusivity models from the renormalization group theory of turbulence [Yakhot, V. and Orszag, S. A., J. Sci. Comput., 1986, 1(1), 3]. Analysis focuses in determini ng how the structure of the side-layer flow, influenced by the wall co nductance ratio and Hartmann and Peclet numbers in the ranges of inter est of fusion blanket applications, affects the heat transfer processe s. Numerical calculations for liquid lithium show that for thin conduc ting wall duct cases, the laminar MI-ID heat transfer mechanism, chara cterized by high-velocity side-wall jets, appears to be more efficient than turbulent mixing in the boundary layer for a given Peclet number . (C) 1997 Elsevier Science Ltd.