Numerical simulation and analysis of liquid metal flow characteristics for fusion related problems

Abstract

Liquid-metal magnetohydrodynamic (MHD) flow is required for proposed blanket designs in nuclear fusion systems. Tritium breeding and tritium self-sufficiency must be ensured for a functional breeding blanket, hence the effect of heating and magnetic fields on liquid-metal flow must be analysed. A study of two fluid dynamics problems related to nuclear fusion blanket and reactor design were conducted in this paper, which are mixed convection in a straight circular pipe and MHD flow in an insulting rectangular duct to simulate the effects of volumetric heating and strong magnetic field on liquid metal flow characteristics. Self-defined computational models were established for both problems using computational fluid dynamics (CFD) software COMSOL Multiphysics 5.4, in which fundamental influences of heat transfer and magnetic field on liquid metal flow were analysed. Both problems were analysed using laminar flow model. The mixed convection problem features a simulation of circular pipe flow of liquid lead-lithium (PbLi) with thermal insulation and heat section in the centre, in which Boussinesq approximation was used in the Navier-Stokes equations. Laminar flow and heat transfer physics are coupled in this case. The MHD flow problem features flow in a rectangular duct with a transverse magnetic field, in which inductionless approximation was used and a self-defined coupling between electric currents and laminar flow physics was established. COMSOL Multiphysics 5.4 was examined to be an efficient and viable numerical tool for the two problems mentioned in the fusion applications.