Mixed convection in a downward flow in a vertical duct with strong transverse magnetic field

TL;DR

This study numerically investigates mixed convection in a downward liquid metal flow within a vertical duct under a strong transverse magnetic field, revealing flow stability and oscillation behaviors relevant to nuclear fusion reactor design.

Contribution

It introduces a two-dimensional model for analyzing flow and heat transfer in magnetically influenced ducts, highlighting the conditions for flow instability and oscillations in fusion reactor applications.

Findings

Flow can be steady or oscillatory depending on heating and magnetic field strength.

Flow becomes unstable and exhibits high-amplitude temperature oscillations under reactor-like conditions.

The model provides insights into the stability of liquid metal blankets in fusion reactors.

Abstract

The downward flow in a vertical duct with one heated and three thermally insulated walls is analyzed numerically using the two-dimensional approximation valid in the asymptotic limit of an imposed strong transverse magnetic field. The work is motivated by the design of liquid metal blankets with poloidal ducts for future nuclear fusion reactors, in which the main component of the magnetic field is perpendicular to the flow direction and very strong heating is applied at the wall facing the reaction chamber. The flow is found to be steady-state or oscillating depending on the strengths of the heating and magnetic field. A parametric study of the instability leading to the oscillations is performed. It is found among other results that the flow is unstable and develops high-amplitude temperature oscillations at the conditions typical for a fusion reactor blanket.