漩流中间包流场的数值模拟

采用CFD软件Fluent对漩流中间包内的流场进行了数值模拟,分析了漩流中间包内的流场特征,以及漩流室的加入,中间包内的流动形态.模拟结果表明,由于漩流室的加入使湍动能耗散主要集中在漩流室内部,有利于夹杂物的聚合长大;漩流室的加入可改善钢液的流动状态,利于夹杂物的上浮.由于入口位置的非对称布置,造成了漩流中间包内的流场在入口区呈明显的非对称分布,这些结果为进一步优化漩流中间包内漩流室的位置和中间包挡墙参数提供了理论依据.     

漩流中间包漩流室内流动状态的研究

分别通过以相似原理为基础,考虑弗劳德数和雷诺数相等,对漩流中间包漩流室内湍流状况的水模型实验研究,以商业软件包为基础,对建立在正交网格上的漩流室内流动进行的以k-ε双方程模型为湍流模型的数值模拟研究,得到了漩流室内的流动状态和旋转速度的分布规律,并系统地研究了漩流室直径、漩流室高度及注人流量对漩流室内的旋转速度的影响。用因次分析的方法分析了水模型和实际中间包内旋转速度之间的相似关系,得到了描述相似规律的准数Rt。为针对不同结构中间包的漩流室优化设计和开发漩流中间包技术提供了理论基础。     

漩流中间包的夹杂物模拟试验研究

根据相似原理,模拟漩流中间包及漩流室内钢液的流动,研究不同漩流室直径、高度对夹杂物在漩流室内向心聚集上浮的影响,验证漩流室对夹杂物的去除效果。结果表明,漩流室的引入有利于夹杂物的上浮去除,夹杂物的上浮率平均由原来的92．35％提高到97％以上。     

漩流中间包中夹杂物去除效率研究

根据相似原理,模拟漩流中间包及漩流室内钢液的流动,研究了不同漩流室直径、高度对夹杂物在漩流室内向心聚集上浮的影响,验证漩流室对夹杂物的去除效果。结果表明,漩流室的引入有利于夹杂物的上浮去除,夹杂物的上浮率平均由原来的92.35%提高到97%以上。     

IFIX软件在连铸机漩流池系统中的应用

以炼钢漩流池系统为背景,介绍了IFIX数据采集与过程监控软件,以及它在漩流池系统中的应用。IFIX软件实现了对生产过程数据实时显示、采集、报警。     

CSP连铸中间包不同控流装置对钢水流动行为影响模拟研究

基于有限元方法,研究了酒钢CSP薄板连铸中间包采用不同的控制流装置布置对中间包流场的影响,结果表明,仅有挡渣墙无挡坝的控流装置钢水在中间包内停留时间最短,流场分布最不合理,第一道挡坝与挡渣墙的距离200 mm,高度200 mm的工况下,中间包流场分布较为合理,研究结果为中间包流场进一步优化改善提供了理论上的指导。     

衡管水平连铸中间包流场分析

根据衡阳钢管水平连铸中间包的实际情况,采用1：1．5的相似比例建立水模拟系统,对水平连铸中间包内钢液流场进行研究．得出水平连铸中间包内钢水流场与弧形连铸中间包内钢水流场的主要区别,提出了优化水平连铸中间包钢水流动的方向。     

非对称5流中间包流场研究及应用

通过水力学模型试验确定了非对称5流中间包最佳挡墙方案,并使用数值模拟研究了中间包内流场及温度场分布规律。研究表明,优化后中间包内温度场及流场稳定均匀,各流水口处钢水平均温差由原4流包的2．5℃降低到1．3℃;投入使用后,各流铸坯夹杂物评级小于2．0级,各流内部组织一致,铸坯质量良好,满足了生产需要和产品质量的要求。     

有限元数值模拟在连铸中间包操作中的应用

建立了三维湍流数学模型,应用有限元软件对连铸中间包内的流场进行了数值模拟,研究了中间包液面深度对中间包流场的影响.计算结果表明,中间包的液面应保持适当高度,过低容易引起中间包液面不稳,不利于夹杂物上浮;过高则容易引起溢钢.     

五流连铸中间包结构优化的水模型实验

以国内某钢厂五流连铸中间包为研究对象,根据相似原理建立了1：3的中间包水模拟系统,考察不同内部结构对中间包流体流动特性的影响．研究结果表明：原型中间包内部结构不合理,各流水口之间的流体流动特性差异很大,存在较大死区．通过内部结构优化设计,使中间包流场得到明显改善,其中方案Ⅵ效果最佳,平均停留时间离散度最小,活塞区体积达23．84％,死区体积为10％,比原型下降了71．70％．     

阳极气泡运动对制钠电解槽内熔盐流场的影响

模拟电解熔盐制钠过程中阳极气泡的运动,测量气泡周围流场的变化,分析阳极气泡运动对电解槽内熔盐流场的影响。利用粒子成像测速仪(PIV)测量得到平行和垂直阳极方向的流体运动,并研究液面高度及气体流量对流场的影响。     

板坯连铸中间包流场模拟分析

针对鞍钢板坯连铸中间包,采用ANSYS系列软件对不同拉速下及增容后的中间包内的钢液流场进行了数值模拟计算.采用水模实验并利用粒子图像测速系统(PIV)对该中间包流场进行测试,其结果和数值模拟结果一致.     

大圆坯连铸用新型旋流水口的数值模拟

通过调整多侧孔水口侧孔射流方向来实现结晶器内钢流的旋转,并设计了一种易于加工、使用寿命长的多侧孔新型旋流水口。建立了圆坯结晶器内三维流动、传热数学模型,计算分析了直筒形水口和新型旋流水口条件下结晶器内的流场和温度场。结果表明：通过调整多孔水口侧孔射流方向可以实现结晶器内钢流的旋转,新型旋流水口能显著降低钢水的冲击深度,促进夹杂物上浮,使热中心上移,提高弯月面的温度。     

Particle image velocimetry in the investigation of flow past artificial heart valves

Full-field measurement of instantaneous velocities in the flow field of artificial heart valves is vital as the flow is unsteady and turbulent. Particle image velocimetry (PIV) provides us the ability to do this as compared to other point measurement devices where the velocity is measured at a single point in space over time. In the development of a PIV system to investigate the flow field of artificial heart valves, many problems associated with the project arose and were subsequently resolved. Experience gained in the setting up of an environment conducive for PIV studies of artificial heart valves; from seed particle selection to refractive index matching, and the evolution of computer algorithms to satisfy the varied flow conditions in artificial heart valves are presented here. Velocity profiles and distributions are computed and drawn for a porcine tissue heart valve based on measurements with the PIV system developed.     

Water Modeling of a Swirling Flow Tundish for Steel Continuous Casting

 A conventional turbulence inhibitor is compared with a swirling chamber from the points of view of fluid flow and removal rate of inclusion in the tundish. Comparing the RTD curves, inclusion removals, and the streamlines in water model experiments, it can be found that the tundish equipped with a swirling chamber has a great effect on improving the flow field, and the floatation rate of inclusion is higher than the tundish with a turbulence inhibitor. Because of the introduction of the swirling chamber, the flow field and inclusion removal in a two-strand swirling flow tundish is asymmetrical. Rotating the inlet direction of swirling chamber 60 degree is a good strategy to improve the asymmetrical flow field.     

Water Modeling of Swirling Flow Tundish for Steel Continuous Casting

A conventional turbulence inhibitor is compared with a swirling chamber from the points of view of fluid flow and removal rate of inclusion in the tundish. Comparing the RTD curves, inclusion removals, and the stream-lines in water model experiments, it can be found that the tundish equipped with a swirling chamber has a great effect on improving the flow field, and the floatation rate of inclusion is higher than the tundish with a turbulence inhibitor. Because of the introduction of the swirling chamber, the flow field and inclusion removal in a two-strand swirling flow tundish are asymmetrical. Rotating the inlet direction of swirling chamber 60 degree is a good strategy to improve the asymmetrical flow field.     

全水口自旋流连铸水口钢水流动行为

摘要： 全水口自旋流连铸是从源头上优化结晶器流场的重要技术,利用数值模拟手段,研究了拉坯速度和旋流发生装置入口尺寸对自旋流连铸钢水流动行为的影响。研究表明,拉坯速度和入口尺寸对水口内钢水旋流具有重要影响,旋流强度随拉速增大而增大,随入口面积增大而减小,且随钢水向下流动近似呈线性减小;当旋流装置入口流速为1.1m/s时,水口内钢水旋转速度达4.10m/s,受旋流影响水口中心钢水反重力向上流动;水口流场沿径向可分为湍流各向同性区、各向异性区和近壁区,随入口速度增加湍流各向异性区范围增大。研究明确了全水口自旋流连铸过程钢水旋流行为的关键控制因素,为旋流连铸的参数优化提供了支撑。     

Flow behavior of molten steel in SEN during full nozzle self swirling flow continuous casting

Full nozzle self swirling flow continuous casting is an important technology to optimize the mold flow field from the source. Numerical simulations were carried out to investigate the influence of casting speed and inlet area of the swirling flow generator on steel flow behavior in SEN (submerged entry nozzle). The results show that the casting speed and the inlet area have important effects on the swirling steel flow in SEN. The swirl intensity increases with the increase of casting speed, decreases with the increase of inlet area, and decreases approximately linearly with the downward flow of molten steel in SEN. The swirling flow velocity can reach 410m/s with the generator inlet velocity of 11m/s. Due to the effect of swirling flow, molten steel at the nozzle center moves upwards. The flow field in SEN along the radial direction can be divided into three regions, namely, the isotropic turbulent fluctuation region, the anisotropic turbulent fluctuation region, and the near wall region. With the increase of inlet velocity, the anisotropic turbulent fluctuation region increases. This study reveals the key control factors on steel flow behavior in a full nozzle self swirling flow continuous casting process, which provides a good support for the parameter optimization of the swirling flow continuous casting process.     

Mathematical Modelling of Water Sampler Filling

Steel samples taken from ladles or tundishes during the steel making process can be of significant importance when monitoring the inclusion size and distribution. In order to preserve the original size and distributions of inclusions in the extracted samples, it is important to avoid their collisions and coagulations inside samplers during filling. Thus, it is necessary to investigate the flow during a sampling process to make sure that this is minimized. In addition, it is important to study the turbulence characteristics, since it is known to influence the inclusion growth. This study presents mathematical modelling of sampler filling using water as a media and experimental results for verification. The study focuses on a lollipop‐shaped sampler since it is one of the most common in the industry. The sampler is filled from an inlet pin located at the bottom centre of the main body. In addition, two different turbulence models, the realizable k‐ε model and Wilcox k‐ω model, were used to study the flow pattern in the sampler. The predictions were compared to experimental results obtained by Particle Image Velocimetry (PIV) measurements. It was found that the flow field predictions using the Wilcox k‐ω model agreed best with the flow field obtained by PIV measurements. Furthermore, it was illustrated that the Wilcox k‐ω model can be used for predictions of the different flow regions as well as the positions of the centres of vortexes which are located near the free surface. Thus, it is concluded that the Wilcox k‐ω model can be used in the future to predict the filling of steel samplers.