钢中不同形状夹杂物在超重力场中上浮模拟研究

Numerical simulation study on the floating of inclusions of different shapes in steel in a supergravity field

  • 摘要: 超重力可促使夹杂物快速上浮,缩短其在钢液中的上浮时间. 为研究夹杂物形状对其在钢液中的上浮行为的影响,本文使用流固耦合方法跟踪计算流体与固体界面状态,在二维纵切面中构建了三种具有不同形态比的夹杂物并在超重力场中进行上浮行为模拟研究. 结果表明,夹杂物的上浮速度与自身形状和上浮角度有关,形态比越趋近1或上浮角度越接近垂直,上浮速度越快. 在重力系数G=1000的超重力场中,长度为1 μm的夹杂物未发生旋转. 长度为10、20 μm的夹杂物会自初始角度(45°、90°)旋转至水平后稳定上浮. 超重力系数会影响夹杂物的旋转状态,随着重力系数的降低,夹杂物的旋转速度逐渐降低. 当G=50时,长度为20 μm的夹杂物(初始角度90°)未能完全旋转;同时也证明相较于垂直角度,初始即倾斜的夹杂物更易发生旋转. 最后,指出通过模型预估离心处理时间应以水平状态下夹杂物的上浮速度为准,并基于该结论给出了夹杂物上浮去除的大致时间.

     

    Abstract: Supergravity is a noncontact volumetric force; when there is a density difference between the two phases, supergravity can strengthen their separation. The removal of nonmetallic inclusions in steel by supergravity technology not only does not cause molten steel to stir back to the mixing but also promotes the rapid floating of inclusions and shortens their floating time in the molten steel. Small inclusions that are difficult to remove can be removed using a supergravity field. The shape of the inclusions affects their floating behavior in molten steel. To study this effect, this study uses the fluid–structure interaction method to track the computational fluid–solid interface state, constructs three inclusions with different aspect ratios in a two-dimensional longitudinal section, and performs simulation studies of the floating behavior of the inclusions in a supergravity field. The effects of the different initial angles of the inclusions on their floating behavior were also compared. The simulation results show that the floating velocity of the inclusions is related to their shape and floating angle, and the faster the floating velocity, the closer the aspect ratio is to 1, or the floating angle is too vertical. For a given length, inclusions with a larger equivalent diameter float faster. In the supergravity field of G = 1000, the inclusions with a length of 1 μm did not undergo rotation; the inclusions with lengths of 10 and 20 μm rotated from the initial angle (45°, 90°) to the horizontal and then floated steadily. The floating velocity of inclusions is related to the real-time angle of inclusions. The rotational state of the inclusions gradually decreases as the gravity coefficient decreases. When G = 50, the inclusions with a length of 20 μm (initial angle of 90°) fail to rotate completely, which also proves that the inclusions are more likely to rotate when initially inclined instead of vertically. In addition, it was concluded that supergravity does not cause anisotropy in steel properties and that the method of removing inclusions from steel by supergravity does not have a substantial negative effect on steel properties. Finally, this study noted that the prediction of the supergravity treatment time using this model should be based on the floating velocity of the inclusions in the horizontal state, and an approximate time for the floating removal of the inclusions is provided based on this conclusion.

     

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