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与气体混合的熔融金属的湍流。 在美国96%的钢都是由钢连铸生产的，结晶器中的多相流问题是最终轧制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、裂片、气泡和昂贵的废品。 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，可以从根本上理解这些缺陷是如何形成的，并找到安全操作条件的窗口以避免它们。 这个赠款机会学术联络与工业（GOALI）计划奖支持创建一个新的计算工具，研究多相流在熔融金属系统与惰性气体注入，并应用此工具，以更好地了解和改善钢连铸，以尽量减少气泡，夹杂物和渣粒的截留。 这将有利于许多涉及这些现象的工程过程。 特别是，这些工具在钢铁连铸中的应用将提高钢坯的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ArcelorMittal的行业团队之间的合作，在进行水模型研究，在运营的钢铁厂中进行测量和试验以及缺陷的冶金分析方面经验丰富。 一个全面的模型系统正在开发，以准确地模拟通过喷嘴耐火材料的气体流动，被动气体吸入低压区域，注射过程中的气泡形成，喷嘴和模具中的不稳定多相流，范围从气泡到段塞流，有和没有电磁效应，颗粒运输和截留到最终产品。 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相关的缺陷的尺寸和位置，以验证模型系统。 经过验证的模型将为缺陷的形成提供新的见解，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。结果将通过联合会和短期课程传达给钢铁行业。

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.