Numerical modelling of liquid metal magnetohydrodynamic flow in an electrically and thermally coupled annulus under reduced gravity

Abstract

For a high-precision spaceborne magnetohydrodynamic (MHD) sensor, temperature drift is troublesome for engineers. The thermal properties of liquid metal MHD (LMMHD) flow in the sensor should be considered. The thermo-fluid behaviour of LMMHD flows and its effect on the output characteristic of the sensor were numerically investigated to explore the underlying mechanism. Based on the Boussinesq approximation, a three-dimensional model of the MHD effect in an electrically and thermally coupled annulus was simplified and implemented in a finite-element framework. The visual patterns of the velocity and electric potential depended on the type of temperature boundary, the magnitude and direction of the applied force, and the angular rate of the inlet and outlet. When the magnitude of the applied force increased from microgravity to gravity, the fluid gradually transformed from a viscous flow to a convective flow. The competitive action between the magneto- and natural convection had a substantial influence on the distribution of the electric potential, as the applied force was perpendicular to the magnetic field. The result will provide a reference for space applications and ground tests of MHD sensors.