控流装置对板坯中间包流场的数值模拟优化

Numerical simulation and optimization of flow field in tundish by flow control device

采用数值模拟的研究方法,利用ANSYS仿真软件建立三维数学模型,模拟中间包内有无控流装置及控流装置的不同组合方式下的钢液流动行为。结果表明,在中间包内设置挡墙、挡坝对钢液流动行为具有显著影响。挡墙与挡坝间距离改变主要影响挡墙与挡坝之间的钢液以及挡坝右侧区域内钢液的流动特征;挡墙高度主要影响挡墙左侧紊流钢液的回流流动,同时影响流向水口方向钢液的速度;挡坝高度的改变影响挡坝右侧钢液的流动,过低的挡坝造成了中间包内钢液的短路流动。挡墙高550 mm、挡坝高350 mm、挡墙距入口处的距离800 mm、挡墙与挡坝间距离400 mm是较为理想的优化控流组合方式。工业生产验证表明,控流装置的优化组合对于中大型夹杂物的上浮去除效果较为明显,20μm以上的中大型夹杂物总占比由23.7%降低至9.1%,且铸坯样中未检测到200μm以上的大型夹杂物。中间包控流装置参数的优化组合有望消除或减轻微合金化铸坯常有的内部夹杂、表层带渣及结瘤等一系列质量缺陷。

The numerical simulation method is adopted,and the 3D mathematical model is established by ANSYS simulation software to simulate the flow behavior of molten steel in tundish with or without flow control device and different combinations of flow control device.The results show that the diversion wall and dam in tundish have a significant effect on the flow behavior of molten steel.The change of the distance between the diversion wall and dam mainly affects the liquid steel flow between the diversion wall and dam,and the liquid steel flow in the right area of the diversion dam.The height of the diversion wall mainly affects the turbulent liquid steel re-flux flow on the left side of the diversion wall and the velocity of liquid steel flowing to the nozzle.The change of the diversion dam height affects the flow of molten steel on the right side of the dam.Too low diversion dam causes the short circuit flow of molten steel in tundish.A relatively ideal optimization flow control combination is that the height of diversion wall is 550 mm,the height of diversion dam is 350 mm,the distance of diversion wall from the entrance is 800 mm,and the distance between diversion wall and dam is 400 mm.The industrial production verification shows that the optimized combination of the flow control device has an obvious upward removal effect on medium and large inclusions.The total proportion of medium and large inclusions over 20μm is reduced from 23.7%to 9.1%,and no large inclusions over 200μm are detected in the slab.It is expected that a series of quality defects such as internal inclusion,surface slag and nodulation of microalloyed slab can be eliminated or alleviated by optimizing the parameters of flow control device.