浸入式水口倾角对宽幅连铸结晶器内流动行为的影响  

Influence of outlet angle for submerged entry nozzle on fluid flow in a wide slab casting mold

作　　者：刘文祥 任磊 LIU Wen-xiang;REN Lei(School of Materials and Metallurgy Rare Earth Institute,Inner Mongolia University of Science and Technology,Baotou 014010,Nei Mongol,China)

机构地区：[1]内蒙古科技大学材料与冶金学院稀土学院,内蒙古包头014010

出　　处：《钢铁》2022年第1期83-92,共10页Iron and Steel

基　　金：国家自然科学基金资助项目(51804171,51774190);内蒙古自然科学基金资助项目(2018LH05030)。

摘　　要：浸入式水口出口角度影响射流的动能损失,进而影响结晶器内的流动行为。建立了比例为1∶4的水模型,在模型拉速为0.425 m/min、水口浸入深度为40 mm的条件下,借助粒子图像测速技术研究了浸入式水口出口倾角为0°和+5°对宽幅连铸结晶器内流动行为的影响。结果表明,0°和+5°水口条件下,射流在模型内的流动方式有很大不同。0°水口时模型内射流在结晶器厚度方向上扩散得更慢,射流接近窄面时,才会沿厚度方向运动到宽面;而+5°时,射流会向上运动到一定高度后返回,其扩散面积更广,这会造成射流在运动到结晶器窄面之前,就对宽面产生了冲击(从水口射出后0.3 s内射流就能运动到宽面),意味着生产时钢液对宽面凝固前沿的枝晶冲刷更强,影响连铸的顺行。钢液流经+5°水口时,先向重力方向冲击水口底部,再折返+5°从水口射出,此过程钢液动能损失大于0°水口,再加上钢液在宽幅结晶器里流经的距离比普通结晶器更长,动能损失更多,这对保护渣熔化不利,容易产生结渣圈现象,影响连铸顺行。对比0°和+5°水口条件下中心截面、1/4截面、靠近宽面的截面流场,可以发现越靠近壁面整个流场流速越小。0°水口时速度由中心面的0.103降至宽面壁面的0.042 m/s,+5°水口由0.097降至0.066 m/s。对0°和+5°水口条件下结晶器内对称与非对称流态进行分析统计,水口出口角度为0°和+5°时,结晶器内对称流态分别占86%和69%,非对称流态分别占14%和31%。The outlet angle of submerged entry nozzle affects the kinetic energy loss of jet,then affects the flow behavior in the mold.A 1∶4 scale water model of slab mold was built.The influence of 0°and+5°nozzles on the flow behavior in wide slab casting mold was studied using particle image velocimetry under the condition that pulling rate was 0.425 m/min and nozzle immersion depth was 40 mm.The results show that there is a big difference in jet morphology between 0°and+5°nozzle.When the angle is 0°,the jet flow is relatively concentrated and spread slowly,it will spread to the wide surface in the direction of thickness when it reaches the narrow surface.However,at+5°,the jet has a process of upward impact and back again,and the expansion range of jet is larger than that of the 0°nozzle.This will make more jets impact the wide surface before reach the narrow front(which can reach the wide surface within 0.3 s).It means that the molten steel scours dendrite at the front of solidification for wide surface more greatly in actual production,which is not conducive to the growth of slab shell.When the liquid steel flows through+5°nozzle,it first impacts the bottom of nozzle in the direction of gravity,and then returns+5°to shoot from the nozzle.In this process,the kinetic energy loss of liquid steel is greater than 0°nozzle.In addition,the liquid steel flows through a longer distance in the wide-width mold than in the ordinary mold,so the kinetic energy is lost more.This is disadvantageous to the melting of slag and affecting the continuous casting.Comparing the flow fields of the center section,1/4 section and section close to the wide surface under 0°and+5°,the closer to the wide face the velocity of the whole flow field is smaller.At the angle of 0°,the velocity decreases from 0.103 m/s in the central plane to 0.042 m/s in the wide face,and it decreases from 0.097 m/s to 0.066 m/s in the angle of+5°.The symmetrical and asymmetric flow patterns in the mold under 0°and+5°conditions were analyzed.At 0°,86%o

关 键 词：浸入式水口倾角 流体流动 宽板坯 连铸结晶器 水模型 

分 类 号：TF777[冶金工程—钢铁冶金]