Interaction between alternating current arcs and Titanium slag pools and its effect on flow and heat transfer

Abstract

The characteristics of the alternating current (AC) arc in the titanium slag electric arc furnace and its interaction with the titanium slag molten pool have significant effects on the material melting and chemical reaction processes. This study, based on fluid dynamics, established a numerical model for the direct coupling of the AC arc and the titanium slag molten pool by considering the electromagnetic field effects and using the volume of fluid method to characterise the interaction between the arc and the molten pool. The accuracy of the model was validated by comparing the simulation results with previous experimental data. Subsequently, the study analysed the effects of different AC current amplitudes and arc lengths on the molten pool flow and heat transfer. The results showed that increasing the current amplitude from 20 kA to 40 kA increased the radius of the molten pool surface pit from 0.093 m to 0.12 m and deepened the depth from 0.031 m to 0.057 m at 0.06 s, indicating enhanced impact and heat transfer from the AC arc to the molten pool. Increasing the arc length from 200 mm to 400 mm increased the radius of the pit on the molten pool surface from 0.11 m to 0.125 m, but shallowed the depth from 0.09 m to 0.051 m. With an increasing arc length, the longitudinal effect of the AC arc on the molten pool weakened, and the lateral effect intensified. Too short arc length may make excessive downward heat hinder the melting of the material on the molten pool surface. Finally, we compared the effects between the AC arc and the direct current (DC) arc on the molten pool flow and heat transfer. It was found that when the 40 kA AC arc (with an effective value of 28.3 kA) was converted to a DC arc with the same effective current value, the radius of the molten pool pit increases from 0.12 m to 0.126 m and the depth deepens from 0.057 m to 0.067 m. The DC arc exerts a stronger impact and more concentrated heat transfer on the molten pool, while the AC arc is more dispersed, potentially favouring more uniform melting of the titanium slag.