Numerical Simulation of the Plasma Arc Melting Cold Hearth Refining Process (PAMCHR)

In order to improve our understanding of the PAMCHR process applied to the processing of Ti alloys, a 3D numerical simulation of the thermal and hydrodynamic behavior of the metal flowing in the refining hearth has been set up, based on Ansys-Fluent CFD software. The solid and liquid phases are governed by a set of transport equations expressing the conservation of mass, momentum, heat, and solutes. The turbulence of the liquid flow is modeled through the standard k–ε model. Heat input and tangential shear stress caused by the plasma jet originating from the torches, as well as the themocapillary effect, are accounted for as boundary conditions. Their effects on the turbulent liquid metal flow have been modeled together with the displacement of the torches. Simulation results are presented for a pilot furnace and representative operating conditions. Turbulent fluid flow in the Ti64 molten pool is analyzed in detail and the role of each momentum source is examined. Comparison between the measured and calculated pool profiles is also reported and reveals a satisfactory agreement.