Numerical analysis of the pre-arcing liquid metal self-pinch effect for current-limiting applications

This paper focuses on the numerical investigation of the pre-arcing liquid metal self-pinch effect in a liquid metal current limiter (LMCL). According to the typical structure of the LMCL, an experimental setup is designed to support this study. A three-dimensional magnetohydrodynamic model, based on the volume of the fluid approach, is used to simulate the dynamic self-pinch process of the liquid metal with a free surface. The distributions of volume fraction, pressure and velocity of the two-phase flow are calculated. The simulation results indicate that the depression of the liquid metal free surface during the self-pinch process is due to the downward gas flow, which eventually leads to the rupture of the liquid metal column and arc initiation in the channel. The expansion phenomenon of the free surface depression observed by both calculation and experiment is caused by the interaction of the pressure field produced by the Lorentz force and the gas flow field. The startup of the self-pinch process depends mainly on the effect of three factors, which are the pressure gradient, flow recirculation and the detaching effect of the Lorentz force.