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Open access

J. Pieprzyca and J. Jowsa

Abstract

A common method used in identification of hydrodynamics phenomena occurring in Continuous Casting (CC) device's tundish is to determine the RTD curves of time. These curves allows to determine the way of the liquid steel flowing and mixing in the tundish. These can be identified either as the result of numerical simulation or by the experiments - as the result of researching the physical models. Special problem is to objectify it while conducting physical research. It is necessary to precisely determine the time constants which characterize researched phenomena basing on the data acquired in the measured change of the concentration of the tracer in model liquid's volume. The mathematical description of determined curves is based on the approximate differential equations formulated in the theory of fluid mechanics. Solving these equations to calculate the time constants requires a special software and it is very time-consuming. To improve the process a method was created to calculate the time constants with use of automation elements. It allows to solve problems using algebraic method, which improves interpretation of the research results of physical modeling.

Open access

J. Jowsa and A. Cwudziński

Thermodynamics Analysis of Non-Metallic Inclusions Formation in the Liquid Steel Flow Through Continuous Casting Tundish

Experiments were conducted at industrial plant to determine the free and total oxygen contents in molten steel in the tundish during continuous casting blooms of sizes 280×280 mm. On the basis of industrial experiment results a thermodynamic evaluation of non metallic inclusion formation in liquid steel was performed. Software FactSage® with thermodynamic base packages were tested and applied to calculate equilibrium formation of oxides and sulphides. The results showed the effect of oxygen contents and temperature on the formation inclusion in liquid steel. Calculation results was presented in the form of suitable characteristics which were illustrated graphically.

Open access

A. Cwudziński and J. Jowsa

Numerical Analysis of Liquid Steel Flow Structure in the One Strand Slab Tundish with Subflux Turbulence Controller and Dam

The paper present the results of computational calculation showing liquid steel flow in the tundish. The one-strand slab tundish is used to casting slabs. The internal work space of tundish was modified by two flow control devices (FCDs). The first device is subflux turbulence controller situated in the pouring tundish zone. The second FCD is a dam with two holes. The dam presently using in the industrial conditions was modified by changing a height. Adapted to internal work space new flow control devices were located in the tundish virtual model. Numerical model and computational grid of tundish was performed in the Gambit application. The visualization of interaction of flow control devices on hydrodynamic conditions was received from numerical simulation. As a results of the computations carried out, liquid steel flow fields, turbulence intensity maps, steel temperature maps and RTD curves (E and F) were obtained. On the distribution of RTD characteristics, percentage contributions of stagnant, plug, ideal mixing flow type, and transition grade zone were calculated.

Open access

J. Jowsa, M. Bielnicki and A. Cwudziński

The 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.

Open access

J. Jowsa, M. Bielnicki and A. Cwudziński

Abstract

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.

Open access

M. Bielnicki, J. Jowsa and A. Cwudziński

Abstract

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-MeshingR. Numerical computations were performed in the programs: COMSOL Multiphysics¯ and Ansys-Fluent¯. 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.

Open access

A. Cwudziński, J. Jowsa and P. Przegrałek

Abstract

The device under examination is a mould of a capacity of 0.5 Mg and with inner cross-section of 280×400 mm. The virtual model of the facility under investigation was made using Gambit, DesignModeler and Meshing programs. Computer simulation of the liquid steel flow and mould flux behaviour in turbulent motion conditions was done using the Ansys-Fluent® computer program. On the basis of earlier researches the volume of fluid (VOF) model was applied. Based on computer simulations carried out, steel flow and flux behaviour fields and curves of flux mould entrainment concentration were obtained. The results obtained from numerical simulation were compared with the data obtained during bloom casting under industrial conditions. Based on the obtained information on the interaction of steel with mould flux, the region was determined, in which conditions likely to favour the entrainment of slag portions into the forming bloom exist.