Numerical investigation and analytical modelling of MHD effects in Lead-Lithium flows within inclined circular ducts of DCLL breeding blankets

The breeding blanket is a key component of nuclear fusion reactors, ensuring heat extraction and tritium breeding. In breeding blankets concepts based on liquid metals, like the Dual-Cooled Lead-Lithium (DCLL) blanket, the exposition to strong magnetic fields leads to magnetohydrodynamics (MHD) effects acting on the flow. Due to the fluid motion, eddy currents are induced inside the fluid and interact with the magnetic field, giving rise to opposing Lorentz forces. They cause significant pressure drop, also reducing the heat transfer efficiency.The present study investigates the impact of the inclination of the duct with respect to the magnetic field on the MHD-induced pressure losses in PbLi flows within DCLL blanket - like geometries. For different values of the inclination angle and keeping constant the boundary conditions, numerical simulations were carried out through the commercial finite element code COMSOL Multiphysics. The numerical results are then compared with two analytical models, introduced in this manuscript, for predicting the MHD pressure drop. The comparison showed consistent trends as the inclination angle varies and highlighted the difference between the two analytical models, given that the first model neglects the conduction currents and the second one is much more based on the expected current path on the section. This comparison allowed us to better understand the role of eddy and conduction currents in the pressure losses besides the impact of geometric parameters. These findings and the analytical modelling can contribute to the optimization of the hydraulic efficiency of the blanket and provide practical tools to facilitate and support the preliminary design of future breeding blankets.