A Mathematical Modeling Study of Tracer Mixing in a Continuous Casting Tundish
A Mathematical Modeling Study of Tracer Mixing in a Continuous Casting Tundish
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DOI：
10.1007/s11663-014-0190-0
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发表时间：
2015-02-01
影响因子：
3
通讯作者：
Jonsson, Par Goran
中科院分区：
文献类型：
--
作者：
Chen, Chao;Jonsson, Lage Tord Ingemar;Jonsson, Par Goran
建立了一个基于水模型的数学模型，用于研究单股连铸机中示踪剂的混合。采用混合组分流体模型模拟了黑色油墨与KCl溶液的混合行为，并与水模型结果进行了验证。此外，一个模型，解决了标量输运方程（STE）没有任何物理性质的示踪剂进行了研究，并将结果进行了比较，使用密度耦合模型的预测。此外，还研究了不同量KCl示踪剂的混合行为。在模型建立之前，KCl示踪剂的性质，如KCl分子扩散（KMD），水分子在KCl溶液中的自扩散（WSD），和KCl溶液的粘度（KV）进行了评估。KMD情况下250 mL KCl的RTD曲线比仅用密度实现的情况更接近水模拟结果。KMD+ WSD、KMD+ KV和KMD+ WSD+ KV三种方案的RTD曲线与KMD方案的总体平均偏差小于0.7%。因此，水的自扩散和KV被忽略，而KCl密度和KMD在本研究中实施。黑色油墨的流动模式与STE结果i相似。例如，流体向上流向顶面并在出口喷嘴处形成大的循环流。100、150和250 mL KCl情况下的流动行为表现出强烈的倾向，即下沉到底部，随后流过坝中的孔。之后，它向出口喷嘴传播。关于KCl示踪剂量，对于较大量的情况，示踪剂浓度传播到出口喷嘴的速度比对于较小量的情况快得多。然而，50 mL KCl情况下的流型略有不同。流体传播到顶部表面，其在初始注射期间表现得像黑色墨水，随后流体以慢得多的速度流过孔。对于100、150和250 mL KCl的情况，模型预测和水模型结果的RTD曲线的突破时间和峰值浓度显示出良好的一致性（所有差异均在12.5%以内）。
A mathematical model based on a water model was developed to study the tracer mixing in a single strand tundish. The mixing behavior of black ink and KCl solution was simulated by a mixed composition fluid model, and the data were validated by water modeling results. In addition, a model that solves the scalar transport equation (STE) without any physical properties of the tracer was studied and the results were compared to predictions using the density-coupled model. Furthermore, the mixing behaviors of different amounts of KCl tracers were investigated. Before the model was established, KCl tracer properties such as the KCl molecule diffusion (KMD), the water molecule self-diffusion (WSD) in KCl solution, and the KCl solution viscosity (KV) were evaluated. The RTD curve of 250 mL KCl for the KMD case was closer to the water modeling results than that of the case implemented with only density. Moreover, the ensemble average deviation of the RTD curves of the cases implemented with KMD+ WSD, KMD+ KV, and KMD+ WSD+ KV to the KMD case is less than 0.7 pct. Thus, the water self-diffusion and KV were neglected, while the KCl density and KMD were implemented in the current study. The flow pattern of black ink was similar to the STE result i. e., the fluid flowed upwards toward the top surface and formed a large circulating flow at the outlet nozzle. The flow behavior of the 100, 150, and 250 mL KCl cases exhibited a strong tendency to sink to the tundish bottom, and subsequently flow through the holes in the dam. Thereafter, it propagated toward the outlet nozzle. Regarding the KCl tracer amount, the tracer concentration propagated to the outlet nozzle much faster for the larger amount case than for the smaller amount cases. However, the flow pattern for the 50 mL KCl case was somewhat different. The fluid propagated to the top surface which acted like black ink during the initial injection, and subsequently the fluid flowed throughout the holes at a much slower pace. The breakthrough time and peak concentration of RTD curves of model predictions and water modeling results showed a good agreement (all difference within 12.5 pct) for the 100, 150, and 250 mL KCl cases.