The development and experimental validation of a numerical model of an induction skull melting furnace

Abstract

Induction skull melting (ISM) is a widely used process for melting certain alloys that are very reactive in the molten condition, such as those based on Ti, TiAl, and Zr, prior to casting components such as turbine blades, engine valves, turbocharger rotors, and medical prostheses. A major research project has been undertaken with the specific target of developing improved techniques for casting TiAl components. The aims include increasing the superheat in the molten metal to allow thin section components to be cast, improving the quality of the cast components and increasing the energy efficiency of the process. As part of this, the University of Greenwich (United Kingdom) has developed a dynamic, spectral-method-based computer model of the ISM process in close collaboration with the University of Birmingham (United Kingdom), where extensive melting trials have been undertaken. This article describes in detail the numerical model that encompasses the coupled influences of turbulent flow, heat transfer with phase change, and AC and DC magneto-hydrodynamics (MHD) in a time-varying liquid metal envelope. Associated experimental measurements on Al, Ni, and TiAl alloys have been used to obtain data to validate the model. Measured data include the true root-meansquare (RMS) current applied to the induction coil, the heat transfer from the molten metal to the crucible cooling water, and the shape of the semi-levitated molten metal. Examples are given of the use of the model in optimizing the design of ISM furnaces by investigating the effects of geometric and operational parameter changes.

Contactless Ultrasound Generation in a Crucible

“…[9,10] Time accurate information is extracted within each AC cycle once a pseudo-steady condition is reached, to enable the driving sound source evaluation for the compressible acoustic simulation.…”

“…The boundary conditions are the no-slip condition at the solid walls (v = 0) or the free surface dynamic and kinematic conditions when the liquid metal is detached from the solid wall (see [9,10] for details). Energy conservation…”

Numerical model of electrode induction melting for gas atomization

“…The numerical simulation technique previously used for magnetic levitation and cold crucible modelling (Bojarevics et al, 2004(Bojarevics et al, , 2000 is applied to the study of electrode induction melting. The numerical code SPHINX has been modified to permit time dependent modelling of the electromagnetic, thermal and fluid flows coupled with the changing free surface.…”

“…We consider an axisymmetric approximation of the ingot and molten film flow with the detailed model representation given in previous publications (Bojarevics et al, 2004(Bojarevics et al, , 2000. The boundary conditions at the external free surface of the viscous turbulent fluid flow are stated for the stress tensor P on the surface:…”

Development, verification and application of numerical model for coupled free surface and liquid metal flow calculation in EM field

“…Free surface dynamics of EM levitated melt, flow and energy transfer in 2D consideration, as well as crystallization processes with free surface behaviour in EM induction furnaces were successfully simulated using simplified twoparameter turbulence models [2].…”