共查询到20条相似文献,搜索用时 390 毫秒
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针对连铸结晶器内钢液的流动、传热、凝固耦合变化问题,应用连续介质力学和能量守恒理论,建立了板坯连铸结晶器内钢液流动、传热和凝固的三维非稳态数学模型。在此基础上,应用COMSOL软件进行数值模拟和分析。将耦合模型计算得到的凝固坯壳厚度与经验公式进行对比验证,总体符合较好。结果表明,结晶器内钢液流动的基本特征与单流场模型相比并没有发生变化。但是,钢液的上、下回流涡心到自由面的距离及流股冲击深度均有所减小。在靠近结晶器窄面的部分区域由于凝固坯壳的形成,不会出现钢液流动现象。由于凝固坯壳的存在,自由面钢液流速变大,自由面钢流波动更加剧烈。由于钢液的强制对流传热,结晶器内部钢液温度并不是由内到外逐渐降低的,而是出现了小幅度的波动。在结晶器出口处钢液温度较低,且分布不均匀,部分区域温度梯度较大。由于钢液的对流作用促进了钢液的热量传递,结晶器出口处窄面、宽面及角部凝固坯壳更厚。 相似文献
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日本及中国的学者研究表明,在连铸过程中浸入式水口内的旋转流动可以有效改善结晶器内的流体流动状态并提高钢坯的表面和内部质量。笔者提出一种新的旋流连铸技术,即利用水口外的旋转电磁场对钢液的洛伦兹力,使水口内钢液形成旋转流动。对圆形电磁旋流装置作用下圆坯及方坯连铸过程结晶器内钢液流场进行了三维数值模拟,分析了350 A电磁旋流作用下圆坯及方坯结晶器内钢液流场。结果表明:①水口电磁旋流使得圆坯结晶器内的钢液都处于旋转状态。②有旋流时,在方坯结晶器角部的附近可以观察到水平流动;钢液的冲击深度更小,上返流增强。 相似文献
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《上海金属》2020,(5)
为消除电磁偏心搅拌给φ380 mm断面圆坯质量造成的不利影响,采用数值模拟方法研究了水口位置对大圆坯连铸结晶器和足辊区内钢液流动和传热的影响。结果表明:在电磁偏心搅拌作用下,大圆坯外弧侧更大的电磁力使从水口进入结晶器的钢液流向外弧侧,并使外弧侧钢液温度升高。将水口向内弧侧偏移后,水口内钢液流向内弧侧,碰到结晶器壁后形成一个较大的回流区,结晶器上部回流区缩小;钢液温度尤其是弯月面处钢液温度明显降低,同时内、外弧侧钢液温差增大。虽然改变水口位置有利于消散钢液热量,但不利于保护渣熔化且增加内、外弧钢液温差,所以改变水口位置的方法不宜用于消除电磁偏心搅拌的不利影响。 相似文献
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连铸钢坯过程中,结晶器处于高温钢液和高速冷却水的综合作用下,结晶器温度场的合理分布是保证连铸正常进行的关键.为得到结晶器内壁界面温度分布规律,设计了模拟结晶器工作过程的试验装置,进行了动态水流和静态水流对结晶器壁温度影响的测试试验.结果表明,结晶器内壁温度趋近于冷却水温度.结合试验数据推导了结晶器界面等效导热系数,用等效导热系数处理钢液与结晶器内壁的边界传热,对连铸钢坯结晶器温度场进行数值模拟,模拟结果与有关研究结果符合. 相似文献
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Diffusion coefficients and mobilities were determined as functions of concentration in the a phase of the Cu-Zn system. Use was made of incremental diffusion couples to determine the Kirkendall effect at various concentrations. Darken’s analysis was used to calculate the individual diffusion coefficients and mobilities from these data. The general diffusion coefficient is a single-valued function of the concentration in this system to within the limits of accuracy of the experimental methods used. The form of the various functions (diffusion coefficients and mobilities) of concentration is the same in every case: it is essentially the same as the usual D vs c curve. 相似文献
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为了在竞争中获胜,欧洲造船业必须提高生产速度和效率,同时降低成本。因此,他们投入了巨大的人力和财力来研发激光焊接并将其应用到造船生产实践中,以达到维持和重建欧洲船厂在全球高附加值船舶市场的优势地位。 相似文献
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This article presents a paradigm for the mechanical properties of a metal that result from the plastic deformation that occurs
in forming processes, including multiple-step or cyclic processes. Some of the new concepts included are a new strength designation
that includes the sense (tensile or compressive), the direction (longitudinal, transverse, etc.), the specific type of deformation
(tensile, compressive, etc.); a concept of an equivalent strain; and the apparent rules of strain strengthening. Examples
of strength 相似文献
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《Acta Materialia》2008,56(6):1243-1256
The Soret effect, as it occurs in the diffusion of solutes in crystals, is analyzed using the principle of microscopic reversibility whereby an approach is developed for interpreting and computing Q1, the heat of transport. To compute the transport of energy during the diffusion jump process, and then Q1, the processes of thermal activation to the transition state and the decay from the transition state are considered to be inverses; thus the net process is reduced to the analysis of the purely mechanical decay process. Molecular statics and dynamics are then suggested as the means to simulate the decay process and the case of carbon diffusion in body-centered cubic α-iron is so analyzed as an example. Our results show that, for the case Q1 ≈ −Qm, where Qm is the activation energy for carbon diffusion, this is in agreement with experimental evidence reported in the literature. Thus both the sign and magnitude of Q1 are correctly predicted. Various cases, such as the diffusion of substitutional solutes and vacancies, are also considered within our approach along with implications for future study. 相似文献