七流连铸中间包流场的数值模拟

采用FLUENT软件对中天钢铁集团公司七流连铸中间包内型流场进行数值模拟,研究速度矢量、湍动能和流体迹线分布规律,分析中间包内有无C型挡墙加入的流场特征.模拟结果表明,加入C型挡墙使中间包的湍动能主要集中在入口区域,利于延长包内各流的平均停留时间,减小死区体积分数,包内各流流动更加均匀,有利于钢液温度和成份的均匀.     

自漩流中间包可行性初探

在离心中间包的设计思路下,提出了一种新型的名为自漩流中间包,并在相似原理的基础上进行了水模型实验.在一流板坯中间包冲击区内安放了一个漩流室,通过刺激响应实验,测量了不同漩流室尺寸(直径和高度)条件下的响应时间和停留时间分布.实验数据的分析表明中间包中漩流室的引入,改变了钢液的流动路径,延长了钢液的停留时间和响应时间,推迟了峰值时间的出现,同时降低了死区的体积,因而这种设计方案在理论上是可行的.     

CSP中间包内腔优化的数值模拟

针对CSP中间包内冶金过程,建立中间包内钢水流场、温度场、夹杂物运动的数学模型,对不同挡墙和挡坝的5种组合方案的中间包钢水,从流动、传热和去夹杂能力等方面进行分析。结果表明:不同挡墙和挡坝的组合方案中,方案5效果最佳,其结构合理,钢液停留时间有效延长,利于夹杂物的上浮;没有明显的低温区域,中间包出口与入口的温差为5℃;对50μm的夹杂物能去除98.4%,对40μm的夹杂物去除率达到92.3%。     

中间包流场数值模拟

利用大型流体计算软件Fluent,对马钢连铸中间包的流场进行数值模拟.将模拟计算结果与现有中间包存在的实际现象对比表明,中间包在现有结构条件下分流和控流装置获得的流场分布不利于中间包钢水中夹杂物的控制和去除.通过改变原有中间包挡墙结构,从而改变中间包内流场分布,彻底改变了中间包中的流型结构,延长了流体质点的运动轨迹,增加了钢液的平均停留时间,为微型夹杂物的去除提供了有利条件.     

板坯连铸中间包内钢液流场和浓度场的数值模拟

采用FLUENT软件对板坯连铸中间包内的流场和浓度场进行数值模拟,分析中间包内有无挡墙以及挡墙参数变化引起中间包内流场、浓度场的变化情况。模拟结果表明,湍流控制器与挡墙的优化配合使中间包内钢液的平均停留时间由502 s延长至573 s,死区体积分数由29.7%降为14.4%,优化挡墙与挡坝参数有利于钢液温度和成份的均匀,及夹杂物的上浮去除。     

底吹气中间包内流动与夹杂物控制

以宝钢集团梅山钢厂1台连铸中间包为原型,采用水模型的方法对底吹气中间包内的流动和夹杂物控制进行研究.结果表明,采用自行设计的装置进行底吹气,能够在中间包内形成均匀、稳定而又细小的气泡;底吹气能够在中间包内形成微气泡形式的"气幕挡墙","气幕挡墙"的形成能有效地破坏中间包内"层流"结构的流动形式,避免形成短路流动,提高平均停留时间,缩小死区体积分率;在吹气位置的选择上,采用中部位置(B2)进行吹气,效果较好;采用底吹气的方式可以实现对中间包内流动的控制,且不需要大的气体流量;底吹气有利于中间包内夹杂物的去除.     

首钢中间包优化设计(Ⅰ)

应用湍流流动数学模型研究了首钢中间包内钢液的流动与混合 ,该模型包括求解三维湍流的N -S方程和k -ε双方程模型 对首钢第二炼钢厂现有中间包的流场和钢液的停留时间做了模拟与分析 ,并预报了在不同位置加设不同高度的坝后 ,中间包内钢液的流动状态及停留时间 结果表明 ,如果坝的设置不当 ,中间包内钢液的流动状态则会更差     

八流中间包内型优化水模实验

根据相似原理,利用水模拟钢液流动来研究中间包内流场的流动状况,通过调节中间包内挡墙位置及其开孔大小来改善和优化中间包内的流场。对比计算机采集的RTD数据及用墨汁作为示踪剂的照片寻求出最优化方案。得出经过改进的中间包各流平均停留时间增加50-90s,死区体积由25％～30％降低到14％～19％,活塞流的体积比从8％～13％增加到26％-27％,优化了中间包内的流场。     

反旋向多漩流器阵列燃烧室流场的数值研究

采用雷诺应力模型(RSTM)对于反旋向多漩流器阵列贫油直喷(LDI)燃烧室的非反应冷态流场进行了数值模拟.研究中采用了一种3×3的漩流器阵列结构,相邻漩流器的旋向交替变化.计算结果表明,所研究的燃烧室流场结构十分复杂.由于相邻漩流器之间对于漩流的强化作用,因而各回流区维持了较长的长度.流场中存在的多个回流区及强湍流表明该燃烧室有潜力实现良好的燃烧性能.通过将雷诺应力模型的模拟结果与LDV实验数据进行比较发现,计算结果与实验值符合良好,说明雷诺应力模型较好地求解了回流区和高速度梯度问题.     

首钢中间包优化设计(Ⅱ)

应用湍流流动的数学模型研究了首钢中间包内钢液的流动与混合,该模型包括求解三维湍流的N－S方程和K－ε双方程模型。对首钢第二炼钢厂现有中间包的流场和停留时间作了模拟与分析,并预报了在不同位置加设不同高度的堰坝后中间包内钢液的流动状态及停留时间。结果表明：如果二重堰的设置不当,中间包内钢液的流动状态则会更差。     

Fluid flow in large-capacity horizontal continuous casting tundishes

The configuration of the tundish for a two-strand horizontal continuous caster was designed and optimized through water modeling. Three designs of the tundish were studied: the original tundish without any flow control devices, the tundish with a turbulence inhibitor at the bottom, and the tundish with an inlet launder and an inclined dam. The residence time, the location and size of the dead zone, and the fluid field pattern were investigated. At the same time, the asymmetry flow field and wavy inlet jet in the horizontal tundish were observed and the reasons for them were discussed. The results indicate that the tundish with an inlet launder and an inclined dam is the best of the three designs.     

粘弹性流体旋转流实验研究

利用粒子图像测速仪(PIV)对圆筒形容器内有自由表面变形的粘弹性流体旋转流动进行了实验研究.旋转流动由等速旋转的容器底面来驱动.实验工质为CTAC(十六烷基三甲基氯化铵界面活性剂)水溶液.测量了水、40×10-6、60×10-6和200×10-6CTAC水溶液在弗鲁德数为2.59至16.3范围内的旋转流动.PIV用来测量子午面内的二次流场,并从PIV图像中抽取自由面高度.结果表明在相似的弗鲁德数下,相比于水流CTAC水溶液旋转流动自由表面中心处的凹陷深度降低,随着溶液浓度或粘弹性升高,子午面内右上角的惯性涡被压缩且强度变得越来越弱.通过与水流动比较并做力平衡分析,定量估算了CTAC水溶液的第一正应力差或弱粘弹性.     

Dissymmetric flow phenomenon in a multistrand tundish

The dissymmetric flow phenomenon exists in a symmetric multistrand tundish. It was studied by the physical simulation experiment. The fundamental flow characteristic of dissymmetry was analyzed. The asymmetry of the flow field, the temperature field, and the inclusions distribution without flow-control devices (FCDs) were compared with those with FCDs. It is proved that the asymmetry of the flow and temperature field along the outlets at the long range is more obvious. The symmetric FCDs installation has a slight effect on the dissymmetric temperature field, simultaneously, the symmetry of the average residence time and the fluid flow pattern has improved, and the fluid flow in the tundish has been more reasonable. In case of a symmetric multistrand tundish having a large volume, the influence of the dissymmetric phenomenon should be considered and the flow behaviors in the whole tun- dish should be studied completely.     

中间包控流装置的物理模拟研究

根据相似原理,建立1∶3的物理模拟模型,通过正交试验考察了挡渣堰、导流坝组合控流装置对中间包流场的影响。研究结果表明,堰坝间距是影响流场的主要因素,优化控流组合方案为：挡渣堰距注入流中心线距离1 200 mm,挡渣堰下沿距包底距离500 mm,导流坝高度360 mm,堰坝间距300 mm.优化后中间包流场趋于合理,钢液在中间包内的停留时间延长,活塞流体积增大,死区体积减小.     

Numerical investigation of the effect of transitory strand opening on mixing in a multistrand tundish

In a multistrand,the outlet near the inlet produces short circuiting flow.This leads to the formation of dead zones inside the tundish,and consequently,the mean residence time decreases.In the present study,numerical investigation of mixing inside a delta shaped tundish with sloping boundaries was carried out by solving the Navier-Stokes equation and employing the standard turbulence model.To decrease the dead zone volume inside the tundish,the effect of closing the outlet near the inlet for a small amount of time and further opening it on the mixing behavior of the tundish was studied.The outlets near the inlet were closed for varying amount of time,and the transient analysis of fluid flow and the tracer dispersion study were carried out to find the mixing parameters of the tundish,namely,mean residence time and the ratio of mixed to dead volume of the tundish.An optimum closure time of the near outlet has been found,which yields best mixing inside the tundish.The numerical code was validated against the experimental observation by performing the tracer dispersion study inside a multistrand tundish and the reasonably good match between the experimental and numerical results in terms of residence time distribution (RTD)curves.The results obtained from the present study confirm the strong role of choosing the right time for opening and closing the outlets to get improved characteristics for the fluid flow and mixing behavior of the tundish.The educational version of computational fluid dynamics(CFD)soft ware PHOENICS was used to solve the governing equations and interpret the results in different forms.     

旋流闪急干燥流场分析

在理论研究和实验分析的基础上,对旋流闪急干燥旋转流场进行了研究,通过对理论式进行无量纳化,拟合得到切向速率分布,轴向速率分布和沿程压力降的经验式。     

Optimization of flow control devices in a single-strand slab continuous casting tundish

The optimization of flow control devices in a single-slab continuous casting tundish was carried out by physical modeling, and the optimized scheme was presented. With the optimal tundish configuration, the minimum residence time of liquid steel was increased by 1.4 times, the peak concentration time was increased by 97%, and the dead volume fraction was decreased by 72%. A mathematical model for molten steel in the tundish was established by using the fluid dynamics package Fluent. The velocity field, conc...     

Design optimization of flow control device for multi-strand tundish

The fluid flow phenomena in tundish have a strong influence not only on the uniform of composition and temperature of bath, but also on the separation of non-metallic inclusions, especially for the multi-strand tundish. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of dam+weir and baffle on the uniform of composition and temperature of bath for different nozzles has been studied. The residence time distribution curves of the fluid flow were measured by SG800. Comparing the photos of the flow pattern in tundish, the optimum arrangement of baf-fle+dam was obtained. This new structure is benefit not only to uniform the temperature among different SENs (submerge entry nozzles) but also to separate the non-inclusions from the liquid steel, it can be widely used in multi-strand tundish.     

Mathematical modeling of fluid flow, heat transfer and inclusion transport in a four strand tundish

Mathematical simulation was used for trouble-shooting and optimization. By the mathematical simulation, fluid flow and beat transfer of molten-steel in a four-strand tundish of a billet caster under different conditions （bare tundish and tundish with flow control device） were analyzed, The results showed that （1） the tundish with flow control device （FCD） has an important effect on the fluid pattern and temperature distribution; （2） the unsteady, solving method was used to model the inclusion motions at different time perthds, and it showed that the FCD is advantageous to separate the nonmetallic inclusions. According to the simulation results, the main problem existing in the industry preduction was found, and some helpful rneasurements were executed. Consequently, the large nonmetallic inclusions were separated, and the content of total oxygen was reduced. The qualily of steel was greatly improved.     

Modeling study on fluid flow and inclusion motion in 6-strand bloom caster tundishes

The behavior of fluid flow and particle motion in a 6-strand bloom caster tundish was investigated by a water model and numerical simulation. Compared with a device without flow control, the tundish with flow control has an important effect on the fluid flow pattern and inclusion removal. It is revealed that by non-isothermal process, which is real production condition, the fluid flow in tundish shows a strong buoyancy pattern, which drives particles to move upwards. The particle removal was quantitatively studied by mathematical and physical simulations.