A coupled systems code - CMHD solver for fusion blanket design

Abstract

Fusion blankets are required to operate in a harsh environment under the influence of a number of synergistic physical phenomena, working across several length scales. The ability to model the thermal-hydraulics of a blanket effectively is key for analysis and design purposes. For magnetic confinement reactor blanket designs using a conducting fluid as a coolant and tritium breeder, the difficulties in flow modelling are particularly challenging due to interactions with the large magnetic field. Blanket analysis is an ideal candidate for the application of a code coupling methodology, with a thermal-hydraulic systems code modelling portions of the blanket amenable to 1D analysis, and a CFD or rather CMHD (Computational Magnetohydrodynamics) solver providing detail where necessary. It is the aim of this study to develop a coupled systems code - CMHD based approach to the modelling of fusion blanket thermal-hydraulics. In particular, it addresses some of the problems associated with the flow of electrically conducting fluids in a high magnetic field. This will enable extensive thermal-hydraulic simulations of the blanket and associated systems to be performed, accounting for MHD effects in a computationally efficient manner that lends itself to the design process. Novel analytical solutions have been developed to address the problem of the electromagnetic coupling of flows between adjacent conducting walled ducts, and for the related heat transfer problem. The resulting correlations have been used in the development of a one dimensional thermal-hydraulic systems code, MHD-SYS. The code has been coupled via TCP socket communications to a CMHD solver (mhdFoam) and the resulting coupled solver has been validated for several test cases. Studies have been performed on simple blanket relevant geometries, comprised of a manifold and several ducts, in order to demonstrate the potential of the coupled solver to capture MHD effects such as modified velocity profiles, increased pressure drops and flow redistribution.