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Prediction and control of powder entrapping at meniscus of molten steel in a continuous casting mold

连铸结晶器钢水弯月面夹粉预测与控制

基本信息

批准号：
07555519
负责人：
HATTA Natsuo
金额：
$ 2.88万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555519/
关键词：
mold powder entrapping numerical analysis multi-phase flow multi-fluid model water model free surface immersion nozzle 流動様式

项目摘要

First, we have analyzed the flow field of molten steel in a continuous casting mold, focusing upon the unsteady behavior of the free surface profile and velocity. The computation has been performed using the MAC-type solution method to a finite differencing approximation of the three-dimensional Navier-Stokes equations for incompressible fluid flow. Here, the non-steady body-fitted coordinate system has been used. According to the numerical results, the effects of the casting speed and the kind of nozzle on the flow structure of molten steel have been found to be remarkable. Also, the experiment has been undertaken to measure the surface velocity distribution, using water instead of molten steel. It has been confirmed that the numerical results are in good agreement with the experimental data.Next, we have numerically analyzed the influence of the free surface fluctuation on the movement of hypothetical spherical materials (instead of melted powder) which are placed just below meniscus. The numerical model for liquid-particles two-phase flow has been built up by incorporating the particle trajectory method into the system of equations on the basis of the two-fluid model. According to the numerical results, the large particles whose diameter are of the order of 1mm rise to the liquid surface in a short time owing to the buoyancy force. On the other hand, motion of smaller particles follows the liquid flow. The flow field is changeable depending on the outflow angle of immersion nozzle as well as the casting speed. Also, it has been found that the powder entrapping occurs owing to the shear stress on condition that two vortical structures are formed near the free surface.

首先，我们分析了连铸结晶器内钢液的流场，着重分析了自由液面形状和速度的非稳态行为。计算已进行使用MAC型解决方案的方法，以有限差分近似的三维不可压缩流体流动的Navier-Stokes方程。本文采用非定常贴体坐标系。计算结果表明，拉速和水口类型对钢液流动结构有显著影响。此外，实验已经进行了测量的表面速度分布，用水代替钢水。数值计算结果与实验数据吻合较好。其次，我们数值分析了自由表面波动对弯月面正下方假想球形材料（而非熔融粉末）运动的影响。在双流体模型的基础上，将颗粒轨道法引入到方程组中，建立了液固两相流的数值模型。根据数值计算结果，大颗粒的直径为1 mm的数量级上升到液体表面在很短的时间内由于浮力。另一方面，较小颗粒的运动跟随液体流动。流场随浸入式水口出流角和拉速的变化而变化。此外，它已被发现，粉末截留发生由于剪切应力的条件下，两个旋涡结构附近的自由表面形成。