上水口环形吹氩对中间包内渣眼形成的影响

 中间包上水口环形吹氩可以在塞棒周围形成清洗钢液的环形气幕，同时部分氩气泡随钢液进入上水口内，可以减少非金属夹杂物在水口内壁的黏附，起到防止水口堵塞的作用。然而，不合理的吹氩量会导致中间包内液面渣层受过强的气液羽流冲击而形成渣眼，使得钢液裸露并发生二次氧化，严重影响铸坯质量。采用标准 k ε 湍流模型研究中间包内流体流动，采用DPM模型和VOF模型耦合方法，研究上水口环形吹氩条件下渣眼的形成及演化规律。结果表明，上水口环形吹氩在塞棒周围形成较强的上升流，塞棒上部邻近区域存在多个涡流区；在钢液涡流的影响下，中间包液渣下层远离塞棒区域，上层向塞棒区域迁移；随着吹氩量的增大，平均湍动能增大，塞棒附近钢液速度逐渐增大，钢渣界面钢液速度先增大后减小，渣眼边缘钢液速度先增大后减小然后再增大，速度与垂直方向夹角逐渐减小；增大吹氩量，中间包熔池液面形成以塞棒为中心的渣眼，渣眼面积逐渐增大。试验条件下不产生渣眼的临界吹氩量为4.2 L/min，对应的钢渣界面最大速度为0.247 m/s，与垂直方向夹角为70°。

Effect of annular argon blowing at upper nozzle on #br# formation of slag eye in tundish

The annular argon blowing at the upper nozzle of tundish can form an annular gas curtain around the stopper rod to clean the molten steel. At the same time, part of argon bubbles enter the upper nozzle with the molten steel, which can reduce the adhesion of non metallic inclusions on the inner wall of the nozzle and prevent the clogging of the nozzle. However, the unreasonable argon flow rate could cause the upper slag layer to be impacted by the excessive gas liquid bubble plumes to form a slag eye, which makes the molten steel exposed and re oxidized, reducing the slab quality. In the present work, the standard k ε turbulence model is used to solve the fluid flow in the tundish. The DPM model and the VOF model coupling method are used to study the formation and evolution of the slag eye with the annular argon blowing at the upper nozzle of tundish. The results show that a strong upwelling flow is formed around the stopper rod, and there are multiple vortex flows in the vicinity of the upper part of the stopper rod. Under the influence of the vortex flow, the lower layer of liquid slag move away from the stopper rod and the upper layer flows from the periphery to the stopper rod. With increased argon flow rate, the average turbulent kinetic energy and velocity of molten steel around stopper rod increases gradually, and the molten steel velocity at the interface of steel slag increases first and then decreases. The molten steel velocity at the edge of slag eye increases initially, followed by a decrease, but then again increases, accompanied by the decrease of velocity angle with the vertical direction. With the further increase of the argon flow rate, a donut shaped slag eye centered on stopper rod is formed on the tundish liquid level, and the area of slag eye gradually increase. The critical argon flow rate of slag eye free is 4.2 L/min in this study, at which the liquid steel velocity of steel slag interface reaches 0.247 m/s, and the dip angle with vertical direction is 70°.