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

许多重要的商业过程涉及熔融金属与气体混合的湍流流动。在美国用于生产96%的钢的钢连铸中，结晶器内的多相流问题是最终轧制钢产品严重缺陷的主要原因。有害的流动模式允许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、碎屑、水泡和昂贵的废品。由于很难在熔融金属环境中进行实验测量，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，并找到安全运行条件的窗口来避免它们。GOALI学术联络机会(GOALI)计划奖支持创建一种新的计算工具，用于研究惰性气体注入的熔融金属系统中的多相流，并应用该工具来更好地了解和改进钢的连铸，以最大限度地减少气泡、夹杂物和渣粒的缠绕。这将使涉及这些现象的许多工程过程受益。特别是，这些工具在钢铁连铸中的应用将提高钢坯质量和美国钢铁行业的竞争力。该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行业团队之间的合作，这些研究人员在运营的钢铁厂进行水模型研究、测量和试验经验丰富，并对缺陷进行冶金分析。目前正在开发一个全面的模型系统，以准确地模拟喷嘴耐火材料中的气体流动、被动气体吸入进入低压区域、注射过程中气泡的形成、喷嘴和结晶器中从气泡到弹状流的非定常多相流以及有或没有电磁效应的多相流动，以及颗粒在最终产品中的传输和捕获。安赛乐米塔尔正在进行系统的测量，以量化许多铸钢板坯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，并将提出和测试改进连铸机操作的方法。这一基础项目是对大学连铸联盟正在进行的实际建模工作的补充，该联盟目前得到11家成员公司的支持。结果将通过该联盟传达给钢铁行业，并将通过短期课程传达给行业。

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.