GOALI: Turbulent Flow Modeling of Gas Injection to Minimize Surface Defects in Continuous-Cast Steel

许多重要的商业过程都涉及到熔融金属与气体混合的湍流。在美国，96%的钢材都是用连铸来生产的。在连铸过程中，模具中多相流的问题是导致最终轧钢产品中大部分严重缺陷的原因。有害的流动模式使颗粒被困在凝固的钢壳中，在那里它们形成永久性缺陷，导致表面针孔、条子、水泡和昂贵的废品。由于在熔融金属环境中进行实验测量的困难，计算模型是一个重要的工具，可以从根本上了解这些缺陷是如何形成的，并找到安全操作条件的窗口来避免它们。这项学术联络与工业（GOALI）计划的资助机会支持创建一种新的计算工具，用于研究惰性气体注入熔融金属系统中的多相流动，并应用该工具更好地理解和改进钢的连铸，以最大限度地减少气泡、夹杂物和渣颗粒的夹带。这将使涉及这些现象的许多工程过程受益。特别是，将这些工具应用于连铸钢将提高钢板质量和美国钢铁工业的竞争力。该GOALI奖项支持在计算建模方面经验丰富的大学研究人员与安赛乐米塔尔的一个行业团队之间的合作，该团队在进行水建模研究、在运营钢铁厂进行测量和试验以及对缺陷进行冶金分析方面经验丰富。目前正在开发一个全面的模型系统，以精确模拟气体通过喷嘴耐火材料的流动、被动气体吸入低压区域、注射过程中的气泡形成、喷嘴和模具中的非定常多相流动（包括有或没有电磁效应的气泡流和段塞流），以及颗粒在最终产品中的传输和夹带。ArcelorMittal正在进行系统测量，以量化许多铸钢板中与气泡有关的缺陷的大小和位置，以验证模型系统。经过验证的模型将为缺陷形成提供新的见解，并提出和测试改进铸机操作的方法。这个基础项目补充了大学连铸联盟正在进行的实际建模工作，该联盟目前由11家成员公司支持。结果将通过联合会传达给钢铁工业，并向工业提供短期课程。

Many important commercial processes involve turbulent flow of molten metal mixed with gas. In steel continuous casting, used to manufacture 96% of steel in the US, problems with multiphase flow in the mold are responsible for most of the serious defects in final rolled steel products. Detrimental flow patterns allow particles to become entrapped in the solidifying steel shell, where they form permanent defects, leading to surface pinholes, slivers, blisters, and expensive rejects. With the difficulty of experimental measurements in the molten metal environment, computational models are an important tool to enable fundamental understanding of how these defects form, and to find windows of safe operating conditions to avoid them. This Grant Opportunity for Academic Liaison with Industry (GOALI) Program award supports creation of a new computational tool to study multiphase flow in molten metal systems with inert gas injection, and to apply this tool to better understand and improve steel continuous casting, in order to minimize the entrapment of gas bubbles, inclusions, and slag particles. This will benefit many engineering processes which involve these phenomena. In particular, the application of these tools to steel continuous casting will improve the quality of steel slabs and competitiveness of the US steel industry. This GOALI award supports a collaboration between University researchers experienced in computational modeling with an industry team at ArcelorMittal, experienced in conducting water modeling studies, measurements and trials in the operating steel plant, and metallurgical analysis of defects. A comprehensive model system is being developed to accurately simulate gas flow through the nozzle refractories, passive gas aspiration into low pressure regions, bubble formation during injection, unsteady multiphase flow in the nozzle and mold that ranges from bubbly to slug flow with and without electromagnetic effects, and particle transport and entrapment into the final product. Systematic measurements are being conducted at ArcelorMittal to quantify the size and location of entrapped bubble-related defects in many cast steel slabs, in order to validate the model system. The validated models will provide new insights into defect formation, and ways to improve caster operations will be proposed and tested. This fundamental project complements ongoing practical modeling efforts at the University Continuous Casting Consortium, which is currently supported by eleven member companies. Results will be conveyed to the steel industry via the Consortium and short courses to industry.