Geometric Optimization of Electrically Coupled Liquid Metal Manifolds for WCLL Blankets

A number of previous theoretical and experimental studies for helium-cooled or water-cooled lead lithium (WCLL) blankets show that the major fraction of magnetohydrodynamic (MHD) pressure drop in the breeder flow originates from manifolds that distribute and collect the liquid metal into and from the breeder units (BUs). Moreover, those studies revealed that without a proper design of the manifolds, the flow partitioning among breeder units would be strongly nonuniform along the poloidal direction. In the present work, MHD flows in electrically coupled liquid metal manifolds are studied by using an efficient hybrid model that has been developed for prediction of MHD pressure drop in such geometries and for determining flow distribution in BUs. The tool combines global mass conservation and pressure drop correlations with detailed 3-D simulations. From the experience gained when applying the model to the geometry of a test blanket module (TBM), it is concluded that the design of the manifolds requires optimization for achieving a balanced flow partitioning among BUs. In the second step, the hybrid model is applied to determine the optimum position of the baffle plates that separate the feeding and collecting ducts in manifolds in order to guarantee comparable flow rates in all BUs.