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EXPERIMENTAL INVESTIGATION OF SEN AND MOULD FOR CONTINUOUS SLAB CASTER BY PHYSICAL MODELLING  [PDF]
PRAVEEN MISHRA,S.K.AJMANI,ARBIND KUMAR,K.K.SHRIVASTAVA
International Journal of Engineering Science and Technology , 2012,
Abstract: Steel makers, at present, are aiming for higher casting speeds of liquid steel, giving equal importance to the product quality. In a continuous slab caster, a higher casting speed leads to several problems, such as higher meniscus fluctuations and frequent vortex formation, resulting in entrainment of slag into the liquid steel. So the control of the meniscus fluctuation plays an important role in attaining a better product quality and this meniscusfluctuations are very much depend upon the flow pattern of molten metal inside the mold.The present investigation was aimed to study the dynamic performance of submerged entry nozzlebased on the water modelling studies for higher casting speed with respect to minimum surface fluctuations.The experiments were carried out to study the effect of different operating parameters on meniscus fluctuations. The performance of 00 and 150 downward rectangular ports were studied by varying the different operating parameters. The wave amplitude of the fluctuations was found to be increasing with the increase in casting speed for both 00and 150downward ports.
COUPLED NUMBERICAL SIMULATION ON SOLIDIFICATION AND SOLUTE TRANSPORT IN THIN SLAB CONTINUOUS CASTING PROCESS
平行板型薄板坯连铸结晶器中钢液流动、凝固及溶质分布的三维耦合数值模拟

LI Zhongyuan,ZHAO Jiuzhou,
李中原
,赵九洲

金属学报 , 2006,
Abstract: A 3-D comprehensively coupled model has been developed for iron-carbon binary system to describe the turbulent fluid flow, solidification and solute transport in the parallel type mold of thin slab. In order to calculate the boundary conditions at the exit of the submerge entry nozzle (SEN), a 2-D model was built according to the practice conditions of bifurcated SEN. The calculated results show that the depth of the injection flow from the SEN into the parallel type mold is much smaller than that in the conventional slab caster due to the small thickness of the thin slab. The jet flow from the SEN impinges on the wide wall strongly especially near the corner of the mold but cannot reach the narrow wall. A nearly-uniform flow field is obtained at the exit of the mold. Under the common action of the fluid flow, solidification and solute distribution, the thinnest thickness of the solid shell on the wide wall appears near the corner and the concentration of carbon changes steeply at the mold exit. This maybe the reason for the very often happened accident of out-of-corner breakout.
EFFECT OF SEN DESIGN ON SURFACE FLUCTUATION AND SOLIDIFYING SHELL IN SLAB MOLD AND ITS OPTIMIZATION

DFWu,SSCheng,

金属学报(英文版) , 2008,
Abstract: Turbulent flow and heat transfer coupled with solidification in slab continuous casting mold was studied by numerical simulation method. Volume of fluid (VOF) model is used to solve steel-air two-phase flow problem and enthalpy-porosity scheme is introduced to solve the fluid flow problem involving solidification. Contributions of various nozzle port angles and port widths and heights on the free surface fluctuation and the thickness of solidifying shell in slab mold were particularly investigated, based on which the structure of submerged entry nozzle was optimized. Flow inside the common nozzle port cannot fill the entire ouaet area, having a recireulation in the upper portion of the port, which is enlarged for the nozzle port with both larger height and width. Results show that the flow in mold cavity is mainly controlled by the nozzle port angle. The increase of the angle of upper face of the port to shape a roughly streamlined inner-wall improves the effective area fraction of the nozzle, resulting in less jet impingement, weaker free surface turbulence and thicker solidifying steel shell.
浸入式水口对结晶器钢水流动与液面波动的影响 Effect of SEN on fluid flow and surface fluctuation in a continuous casting slab mold  [PDF]
张开天,刘建华,崔衡,钱学海,邓深
- , 2018,
Abstract: 以国内某钢厂220 mm×1800 mm板坯连铸结晶器为原型,根据相似性原理建立相似比为0.6的水模型,利用粒子图像测速技术(PIV)对比不同浸入式水口(SEN)的出口角度、浸入深度及水口底部结构条件下的结晶器内流场流速特征,同时使用波高仪对液面波动振幅进行实时监测,并结合F数分析各SEN条件对结晶器内钢液流动特征.研究发现,在各浸入式水口条件下,位于结晶器液面1/4宽面处附近出现矢量流速向下的剪切流,同时在水口附近发现不规则漩涡.试验结果表明:浸入式水口的出口角度、浸入深度的增加能够强化上回旋区缓冲作用,降低结晶器液面表面流速;尽管凹底结构SEN能减弱钢液湍动能,但其对1/4宽面处剪切流速度的影响不大.另外,液面波动幅度和F数变化规律一致,且当浸入式水口出口角度15°、20°,浸入深度135 mm、145 mm条件下波幅与F数最为合理,从而减小或避免液面卷渣,提高连铸坯质量.
REVIEW ARTICLE ON PHYSICAL AND NUMERICAL MODELLING OF SEN AND MOULD FOR CONTINUOUS SLAB CASTING
PRAVEEN MISHRA,S.K. AJMANI,ARBIND KUMAR,K.K.SHRIVASTAVA
International Journal of Engineering Science and Technology , 2012,
Abstract: Over the years, considerable efforts have been made to study the performance of Submerged Entry Nozzle (SEN) and mould of continuous slab caster. Numerous physical and numerical modelling studies have already been carried out and reported in the literature to study the fluid flow behaviour inside the mould. Based on the extensive literature search, a summary of these is presented here. For the sake of convenience, the studies have been categorized into two major groups, e.g., physical modelling and numerical modelling. In each of these categories, a large number of publications on various aspects have been reported. Sufficiently reliable numerical models are also currently available and these also allow one to carry out full scale predictions and useful engineering design calculations.
CFD Model Study of a New Four-Port Submerged Entry Nozzle for Decreasing the Turbulence in Slab Casting Mold  [PDF]
Debasish Chatterjee
ISRN Metallurgy , 2013, DOI: 10.1155/2013/981597
Abstract: In recent years, the continuous casting process in which molten metal is constantly cast into semifinished shapes has been widely adopted in the steel and nonferrous metal producing industry, mainly due to its economic advantages associated with increased yields and the elimination of intermediate processing steps. Turbulent flow in submerged entrance nozzle and mold of continuous casting is associated with costly failure such as the entrainment of slag inclusions and the formation of surface defects. A number of previously studies have analyzed the flow. A CFD model study has done to decrease the turbulence within the mold by developing a 4-port submerged entry nozzle in comparison with conventional 2-port submerged entry nozzle. VOF (volume of fluid) simulation study has been done to find out the effect of turbulence within mold on slag metal interaction, level fluctuation, and risk of breakout. In all the cases the performance of new 4-port SEN over 2-port SEN has been compared by plotting graph. 1. Introduction Steel maker around the world is emphasized to increase the production rate to cope with the global demand of steel in coming decade. Simultaneously the supply of quality steel is demanding by customer. But to meet this stringent demand is very difficult as production machine has certain drawbacks and limitations. One of these drawbacks is creation of turbulence within mold during casting of steel at high casting speed. The submerged entry nozzle (SEN) with two bifurcated ports is commonly applied in slab continuous casting. As the source of the flow, the SEN decides on the steel flow pattern in the mold. For unreasonable nozzle design, impingement of hot liquid metal with high momentum against the solidifying shell can contribute to shell thinning and costly breakout as well as large surface fluctuation [1]. Scientists have been interested in the fluid flow that is observed in the mold during continuous casting because the flow pattern affects the inner and the surface quality of the steel slab to a great extent. Figure 1(a) shows the basic phenomenon produced in the mold during the continuous casting. The flow pattern depends on the structure of the submerged entry nozzle (SEN) and other relative parameters. On the one hand, a calm and smooth mold level assists the uniform formation of the strand shell in circumferential direction and reduces the thermomechanical stresses in the strand shell. It also allows the homogeneous intake of casting powder into the lubrication gap between the strand shell and the mold wall and this, in turn, is
The Condition for Formation of a Double-Recirculation Flow Pattern in a Slab Continuous Casting Mold with Argon Gas
吹氩板坯连铸结晶器内双循环流的形成条件

CAO Na,ZHU Miaoyong,
曹娜
,朱苗勇

金属学报 , 2008,
Abstract: The formation of a double-recirculation flow pattern(DRFP) in continuous casting mold will be helpful for the improvement of slab quality. In the present study, the condition for the formation of the DRFP in a slab continuous casting mold with blowing argon gas was quantitively described using the Lagrange multi-phase flow model, and the prediction was validated by the water model. The influences of argon gas volume flowrate, fluid steel mass flowrate, mold width, submergence depth of SEN (Submerged Entry Nozzle) and port downward angle on the DRFP were numerically investigated. The results show that it is important for ensuring the DRFP that the argon gas flowrate matchs the other casting conditions. The critical argon gas flowrate increases with the increasing fluid steel mass flowrate, and the range of argon gas flowrate for keeping the DRFP will be enlarged by decreasing the mold width and increasing the submergence depth of SEN as the fluid steel mass flowrate is more than 2.486 ton/min, nevertheless, the port downward angle of SEN has little effect on it. However, the operation parameters have no significant influence on it as the fluid steel mass flowrate is below 2.486 ton/min.
Numerical Simulation for the Interfacial Behavior of Steel and Slag in a Slab Continuous Casting Mold with Blowing Argon Gas
吹氩板坯连铸结晶器内钢/渣界面行为的数值模拟

CAO Na,ZHU Miaoyong,
曹娜
,朱苗勇

金属学报 , 2008,
Abstract: A mathematical model to describe the interfacial behavior between fluid steel and molten slag layer in a slab continuous casting mold with blowing argon gas was developed, and the prediction was validated by the water model. The influences of casting speed, argon gas volume flowrate, mold width, submergence depth of SEN (Submerged Entry Nozzle) and bubble size on interfacial behavior were numerically investigated. The results show that given a casting speed 1.8m/min, the upper circulating flow in the mold gradually disappears and the interfacial uneven disturbed by argon bubbles is gradually evident with the increasing argon gas flowrate. Raising the casting speed from 1.2m/min to 2.2m/min leads to the deeper penetration of bubbles and less influence of argon bubbles on the flow pattern and interfacial profile with a given argon gas flowrate. Increasing the submergence depth of SEN can effectively restrain interfacial oscillations in mold, while mold width has little effect on it. Bubble size has a remarkable influence on the interfacial behavior of molten steel and slag in mold.
NUMERICAL SIMULATION OF LIQUID STEEL SUPERHEAT REMOVAL IN SLAB CONTINUOUS CASTING MOLD
板坯连铸结晶器内钢液过热消除过程的数值模拟

YU Haiqi,ZHU Miaoyong,
于海岐
,朱苗勇

金属学报 , 2009,
Abstract: Mathematical model was developed to study the 3D temperature distribution and heat transfer from superheated liquid steel to the inside of the solidifying shell in the slab continuous casting mold. The effects of some factors, such as submergence depth and port angle of submerged entry nozzle (SEN), mold width, casting speed, superheat temperature, argon gas injection, electromagnetic brake (EMBr) and also including the argon gas flow rate and current intensity etc., on the temperature distribution and heat transfer of superheated liquid steel in the mold were analyzed. The results indicate that the maximum heat input to the solidifying shell forefront occurs near the impingement point of liquid steel on the narrow face of mold, and the most superheat of superheated liquid steel is dissipated near the impingement zone. Heat flux of superheated liquid steel delivered to the shell surface increases in direct proportion to the casting speed and superheat temperature, respectively. Argon gas injection leads to a substantial increase in superheat flux to the impingement zone of narrow face and the upper region of wide face. EMBr is beneficial in increasing the temperature of upper region of the mold, but has no obvious effect on the heat flux distribution. The double action of argon gas injection and EMBr also produces an increase in heat flux to the upper region of wide face, which has no visible influence for the hat flux distribution of impingement zone.
Numerical Simulation for the Interfacial Behavior of Steel and Slag in a Slab Continuous Casting Mold with High Casting Speed
高拉速板坯连铸结晶器内钢/渣界面行为的数值模拟

CAO Na,ZHU Miaoyong,
曹娜
,朱苗勇

金属学报 , 2007,
Abstract: The entrainment of steel and slag interface has a great effect on casting process and the product quality. The research described the interfacial behavior between fluid steel and molten slag layer in a slab continuous casting mold with high casting speed by numerical simulation method. Good agreement between the mathematical model and experimental observation was obtained. The influences of casting speed, mold width, port angle, submergence depth of SEN and molten slag viscosity on interfacial behavior were investigated. For a given casting speed, increasing the penetration depth and downward port degree can effectively restrain interfacial oscillations. Molten slag viscosity has hardly influence on interfacial profile of steel and slag. Steel-slag interface velocity decreases with increasing molten slag viscosity.
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