Water Modeling of Steel Flow, Air Entrainment and Filtration
نویسنده
چکیده
This paper presents an analysis of water modeling of steel pouring to study (1) air entrainment and (2) filter effectiveness to remove reoxidation inclusions. In the first part, a review is presented of the physical processes and parameters important in air entrainment in free-surface flows. Then, the use of a water system to model air entrainment in steel pouring is analyzed. Attention is focused on an oneto-one, full-scale model of the casting system. It is shown that the similarity requirements reduce to proper matching of the so-called Z parameter which contains only liquid properties. Large uncertainties in the value of Z for the steel system and a lack of knowledge of the dependence of the air entrainment rate on Z suggest small-scale experiments using metals. Nonetheless, if the Z parameter can be matched, the air entrainment rate in the model will be the same as during pouring of liquid steel. Additional similarity requirements regarding air transport, oxidization and detrainment are also discussed. There is little hope in water modeling of the oxidizing reactions in the steel system. The second part analyzes the usefulness of water modeling to simulate the removal of reoxidation inclusions from the molten steel using a ceramic filter. It is found that the flows of the liquid steel and the inclusions through the casting system and the filter can be well simulated by using an one-to-one, full-scale water model, the same filter, and simulated inclusions of the same size and shape as the reoxidation products. Due to the purely mechanical nature of the entrapment process for particles larger than 100 μm, it can then be expected that the filtration efficiency in the steel system and water model is the same. In addition, the similarities in the flows permit the use of a water model to study the inclusion transport and the effect of the filter on laminarizing the flow. Limitations and uncertainties in water modeling of steel filtration are also discussed.
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