Present understanding of MHD and heat transfer phenomena for liquid metal blankets

A review of experimental work on magnetohydrodynamic (MHD) and heat transfer (HT) characteristics of liquid metal flows in fusion relevant conditions is presented. Experimental data on MHD flow pressure drop in straight channels of round and rectangular cross-section with electroconducting walls in a transverse magnetic field show good agreement with theoretical predictions, and simple engineering formulas are confirmed. Less data are available on velocity distribution and HT characteristics, and even less data are available for channels with electroinsulating walls or artificially made self-healing electroinsulating coatings. Some experiments show an interesting phenomena of HT increase in the presence of a transverse or axial magnetic field. For channels of complex geometry - expansions, contractions, bends, and manifolds - few experimental data are available. Future efforts should be directed toward investigation of MHD/HT in straight channels with perfect and nonperfect electroinsulated walls, including walls with controlled imperfections, and in channels of complex geometry. International cooperation in manufacturing and operating experimental facilities with magnetic fields at, or even higher than, 5-7 T with comparatively large volumes may be of great help. (orig.)