This paper presents the results of laboratory experiments with the usage of water model of continuous steel casting mold for slabs casting. In laboratory experiments, the liquid slag layer is replaced by silicone oil, whereas mold powder layer is replaced by polypropylene particles. The obtained results has been analyzed using a statistical method based on Taguchi assumptions. Critical casting speeds are determined depending on the viscosity of liquid mold slag. Possible mechanisms of slag entrainment are also specified. It is explained, whether taking into account in laboratory experiment the presence of mold powder layer change the entrainment conditions. Based on the obtained results and their discussion it is concluded, that the presence of mold powder should not be ignored in laboratory experiments of continuous steel casting in mold, because to a certain extent it changes the behavior and entrainment conditions of the oil layer.

The paper reports the results of numerical simulation of the flow of liquid steel with the use of a multiphase model. The facility under study was a mould designed for continuous casting of steel slabs. The geometry of the facility, along with the computational grid, was generated within the program Ansys-Meshing R . Numerical computations were performed in the programs: COMSOL Multiphysics R and Ansys-Fluent R . The use of the multiphase model enabled the determination of the behavior of the liquid slag layer on the metal bath surface. From the performed computer simulations, the fields of liquid steel motion and liquid steel turbulence kinetic energy distribution in the mould's symmetry plane have been presented. Based on the values recorded at selected measurement points located on the slag surface, a diagram illustrating the variation of the slag layer position during continuous steel casting has been plotted.Keywords:continuous casting mould, liquid steel, slag, multiphase fluid flow model W niniejszej pracy przedstawiono wyniki symulacji numerycznej przepływu ciekłej stali z wykorzystaniem modelu wielofazowego. Badanym obiektem był krystalizator przeznaczony do ciągłego odlewania stalowych wlewków płaskich. Geometrię obiektu wraz z siatkę obliczeniową wygenerowano w programie Ansys-Meshing R . Obliczenia numeryczne wykonano w programach: COMSOL Multiphysics R i Ansys-Fluent R . Zastosowanie modelu wielofazowego pozwoliło na określenie zachowania się warstwy ciekłego żużla na powierzchni kąpieli metalowej. Na podstawie wykonanych symulacji komputerowych zaprezentowano pola ruchu ciekłej stali oraz rozkładu kinetycznej energii turbulencji ciekłej stali w płaszczyźnie symetrii krystalizatora. Bazując na wartościach zarejestrowanych w wybranych punktach pomiarowych, znajdujących się na powierzchni żużla, sporządzono wykres obrazujący zmianę położenia warstwy żużla podczas ciągłego odlewania stali.

This paper presents results of model tests, performed in order to analyze phenomenon of slag droplets entrainment into steel in mould, during continuous casting process. The carried out studies took the form of laboratory experiments using physical model, in which -using similarity criteria -the behaviour of interfacial boundary liquid steel-liquid slag has been simulated using water and silicon oils, differing in physicochemical properties. Additionally, based on PIV (Particle Image Velocimetry) measurements and numerical simulations, vector flow field and values of critical velocities, at which observed the occurrence of interfacial boundary silicon oil-water instability have been identified. Based on the carried out investigations, results, that illustrate relationship between critical entrainment velocity and physicochemical properties of oils have been presented.

NumerIcal modellINg of metal/flux INterface IN a coNtINuous castINg mouldModelowanie nuMeryczne powierzchni Międzyfazowej Metal/ciekły żużel w krystalizatorze do ciągłego odlewania staliThe behaviour of liquid slag in the mould is one of the key research areas of the continuous steel casting process. Numerical simulations of steel casting in the mould equipped with submerged entry nozzle, intended for slab casting, have been carried out within the study. For modelling the behaviour of the interfaces of the liquid steel -liquid slag -air system, the VOF method was employed. In the conducted simulations, seven different procedures for the discretization of the interface of individual phases were tested. The computation results have revealed that the "entrapment" of fine slag portions into liquid steel occurs in the system under investigation; the cause of this phenomenon is explicated by the Kelvin-Helmholtz theory.Keywords: continuous casting, numerical simulation, Volume of Fluid method, interface tracking schemes, mould flux entrainment.Badania zachowania się ciekłego żużla w krystalizatorze mają istotne znaczenie dla procesu ciągłego odlewania stali. w pracy przeprowadzono symulacje numeryczne odlewania stali w krystalizatorze z wylewem zanurzeniowym, przeznaczonym do odlewania wlewków płaskich. do modelowania zachowania się granic międzyfazowych układu: ciekła stal -ciekły żużel -powietrze zastosowano metodę Volume of Fluid (VOF). Podczas prowadzonych symulacji weryfikowano siedem różnych procedur dla dyskretyzacji granicy rozdziału poszczególnych faz. wyniki obliczeń wykazały, że w badanym układzie dochodzi do "zaciągania" drobnych porcji żużla do ciekłej stali, przyczynę tego zjawiska tłumaczy teoria kelvina-Helmholtza.

The paper presents results of physical and numerical modeling of liquid slag entrainment during continuous casting of steel slabs process. The main aim of this work was to determine the critical casting speed and also to specify, which entrainment mechanism is most responsible for transport of slag droplets into steel volume. Physical modeling was based on water-oil model of mould, made on reduced linear scale of Sl = 0.4. In mathematical modeling, Realizable k-ε and LES WALE models were used to describe turbulent motion of water and oil, whereas Volume of Fluid model was used to take into account interactions between phases. It was found, that the main cause of slag entrainment is the formation of von Karman vortex in the vicinity of submerged entry nozzle. The results of laboratory experiments and numerical simulations were compared each other. Both method are a useful tools for modeling of slag entrainment. Great agreement was found between laboratory experiments and numerical simulation carried out using LES WALE model, regarding the shape of the oil and oil entrainment as a result of vortex structures formation. However, in the simulation case using Realizable k-ε model, the oil entrainment hasn’t been modeled for the conditions under consideration.