Bernardo Martins Braga

Similarity Criteria for the Study of Removal of Spherical Non-metallic Inclusions in Physical Models of Continuous Casting Tundishes: A More Fundamental Approach

Physical modeling is widely used for studying steelmaking processes. The accuracy of this technique depends on the use of appropriate similarity criteria during experimental design. The present work deduced rigorously the similarity criteria for the study of spherical non-metallic inclusions in isothermal physical models of tundishes. Initially, macroscopic quantities were used to simplify the multiphase problem. Then, the similarity criteria were obtained from the dimensionless form of the exact equation of motion for an inclusion in Stokes regime. The validity range of these criteria was discussed and they were compared with common literature practice. Some practical considerations were also presented. This work clarifies various implicit assumptions usually adopted in literature. Additionally, a restrictive criterion to choose the density of the inclusion simulating particles was obtained, which can be satisfied, for example, by hollow glass particles in water models. This criterion is necessary to adequately describe the inclusion motion in regions where fluid elements suffer strong acceleration (e.g., inside nozzles, near flow controllers or in the entering fluid jet). Moreover, it was established an upper limit for the concentration of particles injected in the inlet nozzle of physical models, which do not simulate the phenomenon of inclusion aggregation.

Description of a New Tundish Model for Treating RTD Data and Discussion of the Communication “New Insight into Combined Model and Revised Model for RTD Curves in a Multi-strand Tundish” by Lei

A new tundish model was proposed for analyzing data of the residence time distributions. It was based on an approximated analytical solution for the model of Sahai and Ahuja, which is described elsewhere. Subsequently, it was applied along with some analytical results for well-mixed tanks in a comprehensive discussion of Lei’s work. This discussion contributed to a better understanding of the RTD theory applied to the analysis of fluid flow in continuous casting tundishes. Consider a one-strand tundish of volume V (m) and fluid flow rate Q (m/s). The theoretical residence time of this tundish, s (s), is: s 1⁄4 V Q 1⁄21

MODELO MATEMÁTICO DA DISTRIBUIÇÃO DE TEMPERATURAS PARA O RESFRIAMENTO DE UM TUBO DE AÇO SUBMETIDO A TEMPERA POR ANÉIS DE RESFRIAMENTO

* Contribuição técnica ao 72o Congresso Anual da ABM – Internacional e ao 17o ENEMET Encontro Nacional de Estudantes de Engenharia Metalúrgica, de Materiais e de Minas, parte integrante da ABM Week, realizada de 02 a 06 de outubro de 2017, São Paulo, SP, Brasil. MODELO MATEMÁTICO DA DISTRIBUIÇÃO DE TEMPERATURAS PARA O RESFRIAMENTO DE UM TUBO DE AÇO SUBMETIDO A TEMPERA POR ANÉIS DE RESFRIAMENTO *