Boundary-Layer Loss in Two-Phase Liquid-Metal MHD Channel Flows

Abstract

Viscous homogeneous two-phase liquid-metal flow in an open circuit MHD channel is solved by the method of matched asymptotic expansions with respect to the reciprocal of Hartmann number, in order to make clear the mechanism of the boundary-layer loss, to estimate its order, and to find some methods to reduce it. It is shown that the flow velocity in the core region is effectively controled by the Hartmann boundary-layer on the insulating walls. The solution of the Hartmann boundary-layer shows clearly how the distribution of the void fraction, the wetness of the liquid-metal against the wall and the aspect ratio of the channel cross-section influence the boundary-layer loss. The order of the boundary-layer loss is estimated by the equivalent external load resistance of the closed circuit MHD channel for invisid homogeneous two-phase liquid-metal flow.