Electromagnetic Control of Flow Distribution Between Parallel Ducts of Liquid-Metal-Cooled Blankets

Abstract

The three-dimensional magnetohydrodynamic (MHD) flow in a pair of finite-length, parallel, equal-area square ducts, connected to single rectangular ducts upstream and downstream is examined. Each duct has a different liner with a thin sheet of metal that is in contact with the coolant and that is electrically insulated from structural walls and from other duct liners, except at the junctions. The objective is to concentrate most of the flow in one of the two parallel ducts by making its metal wall much thinner than that of its neighbor, so that its MHD resistance to flow is smaller. Flow ratios approaching ten are obtained with typical values of the wall conductance ratios, which are proportional to the wall thicknesses. The flow at the entrance is complex, with some flow entering the low-velocity duct and then returning to the entrance, where it swirls around the upstream edge of the common wall to enter the high-velocity duct. The balance between three-dimensional and fully developed pressure drops is investigated as a function of the distance between the entrance and the exit of the parallel ducts.