Characterization of LM MHD flow and pressure drop across an electroconductive inlet manifold for fusion reactor blankets

Manifolds are implemented in fusion reactor blanket designs to distribute the breeder into channels and collect it after it serves its function. For blanket concepts using liquid metal as a breeder, regions of expansion and contraction in manifolds present the challenge of high pressure drops associated with the 3D magnetohydrodynamic (MHD) effect in the flows. Previous studies have shown that a more gradual change in the geometry can help reduce the associated flow disturbance and pressure loss. In this study, a 3D computational model of LM MHD flow in an electroconductive inlet manifold featuring gradual expansion was created and solved numerically in COMSOL Multiphysics for a fixed expansion ratio of 4, fixed expansion angle θ = 45°, Hartmann numbers 100 < Ha < 1,000, Reynolds numbers 100 < Re < 1,000, and wall conductivity ratios 0.1 < c_w < 10. First, the built-in MHD module was validated and verified for 2D and 3D classic MHD problems. Then, the coupling between the LM flow, channel walls, and plasma-confining magnetic field is shown through flow velocity changes, pressure drops, electric current paths, and electric potential distributions. The relation between MHD pressure drop and Ha, Re, θ, and c_w is further explored and summarized to help optimize future blanket manifold designs.