Magnetohydrodynamic considerations for the design of self-cooled liquid-metal fusion reactor blankets

During the course of the Blanket Comparison and Selection Study, magnetohydrodynamic effects were shown to prevent not only an efficiency but also a feasibility issue for self-cooled liquid-metal blankets, especially for tokamak machines. Based on state-of-the art MHD analyses and understanding of related phenomena, designs for both mirror and tokamak machines were developed. Although details of the designs depend on specific reactor parameters, MHD related considerations were the main driver in the development of the designs. This paper presents, in a unified way, these considerations, as well as effective strategies to minimize adverse MHD effects so that they can be used as guidelines by others in future design efforts

ALEX results: A comparison of measurements from a round and a rectangular duct with 3-D code predictions

Recent results of liquid-metal magnetohydrodynamic (MHD) measurements from a rectangular duct and earlier measurements from a round duct are reported. A fully three-dimensional numerical analysis of each test section in the fringing region of an applied magnetic field is briefly described. The results of the experiments and the 3-D code predictions are compared and discussed. Excellent agreement is obtained in both test section geometries for interaction parameters ranging from 500 less than or equal to N less than or equal to 1.25 x 10/sup 5/. 9 refs., 7 figs., 1 tab

MHD (magnetohydrodynamic) thermal hydraulic analysis of three-dimensional liquid metal flows in fusion blanket ducts

Magnetohydrodynamic flows of liquid metals in thin conducting ducts of various geometries in the presence of strong nonuniform transverse magnetic fields are examined. The interaction parameter and Hartmann number are assumed to be large, whereas the magnetic Reynolds number is assumed to be small. Under these assumptions, viscous and inertial effects are confined in very thin boundary layers adjacent to the walls. At walls parallel to the magnetic field lines, as at the side walls of a rectangular duct, the boundary layers (side layers) carry a significant fraction of the volumetric flow rate in the form of high velocity jets. The presence of these jets strongly enhances heat transfer performance. In addition, heat transfer can be further improved by guiding the flow toward a heated wall by proper variation of wall thicknesses, duct cross sectional dimensions and/or shape. Flows in nonconducting circular ducts are also examined. Experimental results obtained from the ALEX experiments at the Argonne National Laboratory are used to validate the numerical predictions. 6 refs., 7 figs

MHD (magnetohydrodynamic) flow tailoring in first wall coolant channels of self-cooled blankets

MHD flow tailoring, the use of salient features of MHD flows in strong magnetic fields to create desirable velocity profiles in single ducts, presents the possibility of significant reduction in blanket complexity and cost, and enhancement of thermal hydraulic performance. A particular form of flow tailoring, involving ducts with alternating expansions and contractions lends itself to the design of first wall coolant ducts. The potential benefits of this configuration and its immediate applicability to blanket design have made it the choice as the first joint Argonne National Laboratory (ANL)/Kernforschungszentrum Karlsruhe (KfK) test on liquid metal MHD. Testing is being carried out at ANL's ALEX facility on a test article fabricated at KfK. A description of the test article, its important features, and the associated instrumentation are presented. A fully 3-D code capable of treating MHD flows in ducts of complex geometry has been developed and used in the flow tailoring experiements. The features and capabilities of the code are discussed and a sample of the code predictions for the geometry and conditions of the experiments are presented. A sample of the preliminary test results from the ongoing testing is also given. 9 refs., 9 figs