Metallurgical aggregates are characterised by the interaction of several phases. Especially within secondary metallurgy vessels like ladles or converters comprises the liquid steel phase, the buoyant liquid slag phase, a gas phase for purging/stirring/processing, and the atmosphere atop. A similar character can also be found within the continuous casting (CC) process where in the submerged entry nozzle (SEN) gas is injected into the liquid steel. This mixture is directed into the mould which comprises the interfaces of steel-slag as well as slag-atmosphere. Furthermore, the interaction of the liquid steel flow field with magnetic fields is used to manipulate the flow to a favourable state.
Within this project the main phase of interest is represented by the liquid steel and its interactions with different phases or external magnetic fields. From a modelling point of view the interfaces of multiphase systems might be tracked by Volume of Fluid (VoF) approaches which are capable to resolve different phases based on the density ratio within the grid cells. Already this point unveils problems since the grid cells of industrial applications need to be quite coarse to achieve reasonable computational times. The requirement of sharp interfaces (e.g. to resolve small bubbles) and especially high injection gas rates need to be further investigated to include all necessary interactions like multiphase-turbulence, interfacial tension gradient triggered convective flows, etc. Moreover, the approach to not resolve the small structures but convert/map them to Lagrangian particles (and vice versa if coalescence increases their size) will be investigated to design a suitable model. Since the common models often neglect or drastically simplify effects which are observed within high temperature flows this project targets the development of applicable and suitable models for the steel industry.
The numerical investigation of metallurgical vessels of industrial size represents a complex task. The involved interactions of several phases (liquid, gas, solid) demand high resolutions concerning temporal and spatial scales to achieve a reasonable digital representation. Since these requirements would result in inadequate computational times the development of smart modelling approaches is mandatory. Each work package within this project focuses on a special part of interaction and its implication on the flow field or refractory wear. The formulation and understanding of interactions like magnetic fields, turbulence interaction, high gas injection rates, or interfacial tension gradients is of fundamental interest for further improvements of the systems.
Results and application
The overall target of this project is the development of detailed models for the interaction of multiple phases appearing within steel industry and especially secondary metallurgy. The modification and development of numerical approaches to cover various scales and enable the application to operational conditions (e.g. high gas rate injection, thermochemical and electromagnetic considerations, etc) represents the main area of investigation. Enabling the numerical analyses with a reasonable detail to computational effort ratio will enhance the understanding of industrial processes itself, their process conditions, and consequently will result in faster and even more optimized design improvements.