Magnetohydrodynamic flow in the European SCLL blanket concept

The pressure drop and flow patterns of fully developed liquid metal flow in a typical geometry of the European SCLL blanket exposed to a uniform magnetic field has been evaluated. The calculations for an outboard blanket in a field of B0 = 4 T show that the pressure gradient in ducts made by electrically insulating walls is about ∇p = 0.0567 MPa/m at maximum velocities of v0 = 4.5 m/s in the annular gap, which seems to be acceptable. The pressure drop in the central duct is very small so that the total pressure drop is mainly created in the annular gap flow. Values for the top and inboard blanket are estimated by extrapolation. It is found that the core velocity profiles along the first wall exhibit a decrease when approaching the walls, which divide the annular gap into a number of sub channels. This ''periodic'' velocity distribution creates non-uniform temperature distributions along the first wall, a fact that has to be considered in future stress analyses. (orig.)