Nonlinear effects of FCI electrical conductivity on the MHD flow in DCLL blanket

Abstract

In a Dual Coolant Lead Lithium (DCLL) blanket, flow channel insert (FCI) with low electrical conductivity and low thermal conductivity is introduced to reduce the MHD pressure drop and improve the heat transfer efficiency. In the present work, we aim at performing a direct simulation of the magneto-thermal-fluid-structure multi-physical fields in a typical poloidal duct with different electrical conductivities of FCI, using a coupled computing platform including CFD and the finite element method (FEM), to study the pressure field, velocity field, temperature field, as well as the deformation and stresses of FCI. A consistent and conservative scheme and PISO method on an unstructured collocated mesh are employed to solve the incompressible Navier–Stokes equations with the Lorentz force included. The results show that: with the increasing of FCI's electrical conductivity (σFCI), the pressure reduction efficiency becomes lower; the pressure difference between the FCI's inside patches and the corresponding outside patches increases after an initial reducing; two jets appear in the side gap and the one near FCI develops to a reverse flow; the variation of the temperature difference across FCI and the interface temperature of first wall (FW) is non-monotonic; the cause of nonlinear variation of thermal deformations and stresses of FCI with electrical conductivity results from the nonlinear effect of Lorentz force on the liquid metal velocity. This work is the theoretical basis of blanket design.