The main differences in the transient zone extent between the individual strands for the former industrial six-strand tundish configuration is the basis for undertaking this study. The aim this study was to improve the casting conditions by proposing the optimal equipment of the tundish working space. For economic reasons, only the variants with different baffles configurations were considered. It was also dictated by the simplicity of construction and the possibility of its implementation by the base operating steel mill. In the current study, industrial plant measurements and mathematical modeling were used. Industrial experimental data were used to diagnose the current state of the industrial tundish and then validate the numerical simulations. After this, the influence of different baffle configurations installed in the tundish on the steel flow characteristic was modeled mathematically. Residence time distribution (RTD) curves are plotted, and individual flow shares for the investigated tundish were estimated based on the curves. Finally, the industrial plant was rebuilt according to the numerical results and additional plant measurements were performed. A result of the appearance of the baffles in the tundish working space was the reduction of the transient zone extent. The results indicate the increasing share of the dispersed plug flow and a decreasing share of the dead volume flow, with a practically unchanging share of well-mixed volume flow in the modified tundish.

The paper shows the results of the research obtained by physical and mathematical modeling of steel flow and mixing in the tundish. Two‐strand continuous casting tundish was under consideration. It has been working in one of polish steel plants. The change of concast slab assortment was caused by the changeable market terms. So, the tundish with the new system of steel flow controller was needed. Up to now baffles with the notch have played this role. Their placement cause the excessive consumption of the lining of the tundish front line. As a consequence the turbulence inhibitor (TI) was applied. Four different types of this inhibitor were designed. As a result of the experimental measurements and numerical simulations, the RTD curves of F‐type were obtained. Basing on these curves time constants for examined types were determined. Additionally, the research results were complemented by the E‐type curves. The percentage participations of dead volume flow, dispersed plug flow, and well‐mixed volume flow were calculated. The research gives possibility to estimate the designed TIs and their influence on the tundish work.

The tundish plays a major role in the continuous casting process. The flow in a tundish has a very substantial effect on the quality of the final product and on efficient casting conditions. Efforts are being made worldwide to obtain the most favourable shape of tundish interior by using dams, weirs and gas curtains. The aim of these flow control devices is to reduce the dead zone areas and improve the conditions for the separation of non‐metallic inclusions. Numerous model studies are being carried out to explain the effect of the tundish working space shape and steel flow conditions on the inclusions floating processes. The presented article shows the results of investigations performed to obtain the mass exchange characteristics in the investigated tundish. The measurements were done directly at the steel plant during normal working conditions. By controlling the changing content of manganese in steel, the residence time distribution (RTD) characteristics were acquired. The RTD characteristics are also obtained with a water model of the tundish with dimensional scale of 1:3. Parallel to the water model, numerical simulation based on mathematical modelling of fluid flow, relying on the system of differential equations, is employed in the research work. Numerical simulations were carried out with the finite‐volume commercial code FLUENT using the standard k‐ε turbulence model. The primary purpose of the investigations carried out is to present the characteristics describing the transitory zone in a six‐strand tundish. It is shown that the F‐curve, describing the transitory zone, can be obtained by using different measurement techniques. Tracer concentration characteristics for the model of tundish obtained from both modelling techniques ‐ physical as well as numerical ‐ are very similar.

Modern tundishes plays an important role of refining treatments to improve the quality and purity of casted steel. Purity of steel is defined by the non-metallic inclusions in the steel product, including their size, quantity, distribution, chemical composition and mineralogy. The aim of presented studies was to investigate the number and distribution of non-metallic inclusion in individual billets casted in a six-strand tundish. The industrial measurements, performed during stable production conditions at the continuous steel casting (CSC) plant, were performed for different tundish working space configurations. Analysis of the size and number of non-metallic inclusions has been done on the metallographic samples using light microscope. Experimental studies were supported with numerical simulations using large eddy simulations (LES) method. A modified boundary condition describing inclusion separation at the liquid steel surface was implemented in commercial code AnsysFluent.Experimental results concern size distribution of inclusions in billets for current tundish configuration showed big differences between casted ingots. Numerical results shown the domination in the number of inclusions occurring in the nozzles number 3 and 4 (for basic tundish configuration) and in the nozzles number 2 and 5 (for tundish with turbulence inhibitor). The reason for that is the change in configuration tundish working space, that has an impact on the flow field inside the tundish. Experimental measurements performed for proposed modified tundish configuration (with turbulence inhibitor) shown that those differences are much smaller, which in consequence has an influence in higher quality of continuously casted ingots for individual strand of CSC.

The refining process is one of the essential stages of aluminum production. Its main aim is to remove hydrogen, that causes porosity and weakens the mechanical and physical properties of casting aluminum. The process is mainly conducted by purging inert gas through the liquid metal, using rotary impellers. The geometry of the impellers and the processing parameters, such as flow rate of gas and rotary impeller speed, influence the gas dispersion level, and therefore the efficiency of the process. Improving the process, and optimization of parameters, can be done by physical modelling. In this paper, the research was carried out with the use of a water model of batch reactor, testing three different rotary impellers. Varied methods were used: visualization, which can help to evaluate the level of dispersion of gas bubbles in liquid metal; determination of residence time distribution (RTD) curves, which was obtained by measuring the conductivity of NaCl tracer in the fluid; and indirect studies, completed by measuring the content of dissolved oxygen in water to simulate hydrogen desorption. The research was carried out for different processing parameters, such as flow rate of refining gas (5–25 L·min−1) and rotary impeller speed (3.33–8.33 s−1). The obtained results were presented graphically and discussed in detail.

The article presents results of the research that was carried out taking into account the influence of the (impact pads) turbulence inhibitor geometry and its equipment of the working space on the hydrodynamic conditions occurring in T-type tundish. Four different turbulence inhibitors were discussed. They differ in shape and configuration of external walls. The research was conducted basing on the numerical simulations as well as on tests performed on physical water model. As a result of calculations the velocity field distribution, turbulence field and marker concentration distribution in the liquid steel for the tested geometrical variants of turbulence inhibitors were obtained. Worked out RTD curves (Residence Time Distribution) allowed to determine the kinetics of steel mixing (the range of transient zone was estimated), and the percentage participation of the particular flow zones. The test carried out on the water model concerned one of the tested turbulence inhibitors. Research was done to verify the parameter settings of the numerical model applied in calculations.Obtained results gave valuable information about the work of the object after applying different turbulence inhibitors. Keywords: tundish, continuous casting, numerical modeling, Residence Time DistributionArtykuł przedstawia wyniki badań wpływu geometrii i sposobu zabudowy inhibitora turbulencji na warunki hydrodynamiczne panujące w przestrzeni roboczej kadzi pośredniej typu T. Rozpatrywano cztery warianty geometryczne inhibitora turbulencji. Inhibitory turbulencji różniły się kształtem i ukształtowaniem ścian wewnętrznych. Badania zrealizowano w oparciu o technikę modelowania numerycznego, oraz eksperyment na fizycznym modelu wodnym. W wyniku obliczeń uzyskano pola prędkości, turbulencji oraz rozkładu stężeń znacznika wprowadzonego do ciekłej stali w przestrzeni kadzi pośredniej dla rozpatrywanych wariantów geometrycznych inhibitora turbulencji. Opracowane charakterystyki RTD (Residence Time Distribution) umożliwiły określenie kinetyki mieszania stali (oszacowano zakres strefy przejściowej), oraz udziały procentowe poszczególnych stref przepływu. Badania uzupełniono o eksperyment na fizycznym modelu wodnym. Dotyczył on jednego z proponowanych wariantów inhibitora turbulencji. Wykonano je w celu weryfikacji doboru parametrów modelu numerycznego w przyjętych w obliczeniach.Uzyskane wyniki dostarczyły cennych informacji o pracy obiektu po zastosowaniu różnych inhibitorów turbulencji.

The liquid steel flow structure in the tundish has a very substantial effect on the quality of the final product and on efficient casting conditions. Numerous model studies are being carried out to explain the effect of the tundish working conditions on casting processes.It is necessary to analyze the structure of liquid steel flow, which is strongly supported with numerical modeling. In numerical modeling, a choice of a proper turbulence model is crucial as it has a great impact on the flow structure of the fluid in the analyzed test facility. So far most numerical simulations has been done using RANS method (Reynolds-averaged Navier-Stokes equations) but in that case one get information about the averaged values of the turbulent flow. In presented study, numerical simulations using large eddy simulations (LES) method were used and compared to RANS results. In both cases, numerical simulations are carried out with the finite-volume commercial code AnsysFluent.Keywords: tundish, continuous casting, numerical modeling Struktura przepływu ciekłej stali w kadzi pośredniej ma bardzo istotny wpływ na warunki odlewania, a tym samym na jakość wyrobu końcowego. W celu określenia struktury przepływu w kadzi oraz analizy jej wpływu na warunki pracy urządzenia do ciągłego odlewania stali (COS) prowadzone są liczne badania modelowe: fizykalne i numeryczne.W modelowaniu numerycznym, wybór odpowiedniego modelu turbulencji jest kluczowy, ponieważ ma ogromny wpływ na strukturę przepływu płynu w analizowanym obiekcie badawczym. Do tej pory, największą ilość symulacji numerycznych przeprowadzono z wykorzystaniem metody RANS (Reynolds-averaged Navier-Stokes equations). W przypadku tej metody dostajemy jednak jedynie informacje o uśrednionych wartościach przepływu turbulentnego, z jakim mamy do czynienia w kadziach pośrednich. W prezentowanej pracy natomiast, przedstawiono wyniki symulacji numerycznych przeprowadzonych z wykorzystaniem metody wielkich wirów (Large Eddy Simulation, LES) i porównano je z wynikami RANS. W obu przypadkach, symulacje numeryczne zostały przeprowadzone z wykorzystaniem komercyjnego kodu AnsysFluent.

Obtaining high-quality aluminum is associated with the use of an effective method of refining, which is argon-purging, in which gas bubbles are introduced into the liquid metal by means of rotary impellers. Various rotary impellers are used in the industry; however, if a newly designed impeller is constructed, it should be tested prior to industrial use. For this purpose, physical modeling is used, which enables the investigation of the phenomena occurring during refining and the selection of optimal processing parameters without costly research carried out in the industry. The newly designed rotary impeller was tested on the physical model of a URO-200 batch reactor. The flow rate of refining gas was: 10, 15 and 20 dm3·min−1, whereas rotary impeller speed was 300, 400 and 500 rpm. The research consists of a visualization test showing the schemes of the gas bubbles’ dispersion level in the liquid metal and experiments for removing oxygen from water, which is an analogue of removing hydrogen from aluminum.