Flow and thermal behavior of the top surface flux/powder layers in continuous casting molds
Flow and thermal behavior of the top surface flux/powder layers in continuous casting molds
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DOI：
10.1007/bf02915666
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发表时间：
1996-08-01
影响因子：
3
通讯作者：
Thomas, BG
中科院分区：
文献类型：
--
作者：
McDavid, RM;Thomas, BG
建立了连铸板坯保护渣层的稳态有限元模型，研究了保护渣层的流动和热行为。三维（3-D）FIDAP模型包括由在钢水池中计算的流速施加在焊剂/钢界面上的剪切应力。它还包括不同的温度依赖性的固化和熔化的粉末性能。三维模型和实验测量之间的良好协议。由钢表面朝向浸入式入口喷嘴（SEN）的运动施加的剪切力在液体通量池中产生大的回流区。其深度随着铸造速度的增加、保护渣电导率的增加和保护渣粘度的降低而增加。对于典型条件，该区域包含几乎4kg的焊剂，这有助于约2分钟的平均停留时间。此外，由于窄面消耗产生的剪切力和钢流彼此相反，所以液态熔剂层中的流动在距窄面壁200 mm的中心位置处分离。这种流动分离耗尽了该位置处的液体通量池，酸可能导致那里的结晶器-铸坯间隙的一般不良进料。作为进一步的结果，在分离点附近的宽面模具壁处形成相对冷点。温度分布的这种不均匀性可能导致不均匀的热去除，并且可能导致弯月面区域中沿着宽面偏离角部区域的不均匀的初始壳生长。以这种方式，潜在的钢质量问题可能与液态熔剂池中的流动相关联。
Steady-state finite-element models have been formulated to investigate the coupled fluid flow and thermal behavior of the top-surface flux layers in continuous casting of steel slabs. The three-dimensional (3-D) FIDAP model includes the shear stresses imposed on the flux/steel interface by flow velocities calculated in the molten steel pool. It also includes different temperature-dependent powder properties for solidification and melting. Good agreement between the 3-D model and experimental measurements was obtained. The shear forces, imposed by the steel surface motion toward the submerged entry nozzle (SEN), create a large recirculation zone in the liquid flux pool. Its depth increases with increasing casting speed, increasing liquid flux conductivity, and decreasing flux viscosity. For typical conditions, this zone contains almost 4 kg of flux, which contributes to an average residence time of about 2 minutes. Additionally, because the shear forces produced by the narrowface consumption and the steel flow oppose each other, the flow in the liquid flux layer separates at a location centered 200 mm from the narrowface wall. This flow separation depletes the liquid flux pool at this location acid may contribute to generically poor feeding of the mold-strand gap there. As a further consequence, a relatively cold spot develops at the wideface mold wall near the separation point. This nonuniformity in the temperature distribution may result in nonuniform heat removal, and possibly nonuniform initial shell growth in the meniscus region along the wideface off-corner region. In this way, potential steel quality problems may be linked to flow in the liquid flux pool.