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China Foundry 2012年第2期9卷 171-177页

作者： Li Wensheng shen houfa Liu Baicheng Key Laboratory for Advanced Materials Processing Technology Ministry of EducationDepartment of Mechanical EngineeringTsinghua University Beijing 100084China

As a necessary step toward the quantitative predictions of macro-segregation commonly found in metal castings, classical experiments and numerical benchmarks have been used to validate a simplified binary- alloy solidification model. The model consists of fully coupled conservation equations for the transport phenomena （heat transfer, solute redistribution, ~tnd melt convection） that lead to macro-segregation in a solidifying ingot with a fixed solid phase. Simulations were performed for solidification of either a Pb-48wt.%Sn or a Sn-5wt.%Pb alloy in a rectangular cavity. The present predictions were compared with experimental data and numerical reference results reported in the literature. Subsequently, the model was applied to a numerical benchmark problem described in the literature for solidification of a Sn-10wt.%Pb alloy. Simulation results for flow velocity, liquid fraction evolution, and macro-segregation maps also were compared with literature predictions, showing similar trends. It is concluded that additional comparisons to experimental results are still required to assess more complex solidification models.

关键词： benchmark solidification macro-segregation thermo-solutal convection

Numerical simulation on multiple pouring process for a 292 t steel ingot

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China Foundry 2014年第1期11卷 52-58页

作者： Tu Wutao Zhang Xiong shen houfa Liu Baicheng Key Laboratory for Advanced Materials Processing Technology Ministry of Education School of Materials Science and Engineering Tsinghua University Sinotrans Ltd.

A ladle-tundish-mould transportation model considering the entire multiple pouring(MP) process is proposed. Numerical simulation is carried out to study the carbon distribution and variation in both the tundish and the mould for making a 292 t steel ingot. Firstly, the fluid flow as well as the heat and mass transfer of the molten steel in the tundish is simulated based on the multiphase transient turbulence model. Then, the carbon mixing in the mould is calculated by using the species concentration at the tundish outlet as the inlet condition during the teeming process. The results show a high concentration of carbon at the bottom and a low concentration of carbon at the top of the mould after a MP process with carbon content high in the first ladle and low in the last ladle. Such carbon concentration distribution would help reduce the negative segregation at the bottom and the positive segregation at the top of the solidified ingot.

关键词： multiple pouring transportation numerical simulation large steel ingot

Modelling of Level Fluctuation in Continuous Casting

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Journal of Materials Science & Technology 2003年第z1期19卷 158-160页

作者： Xiao LIU Huanxin ZHANG Rongjun XU Yongquan LI houfa shen Baicheng LIU Baoshan Iron and Steel Co. LTD. Shanghai 201900 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China Baoshan Iron and Steel Co. LTD. Shanghai 201900 China Baoshan Iron and Steel Co. LTD. Shanghai 201900 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

The free surface profile and fluid flow in the mold of continuous casting have been calculated by the VOF method couplingthe SIMPLER algorithm. The SIMPLER-VOF model developed is validated by solving a classical experiment, broken damproblem. The calculated surface profile is consistent with water modelling. It is found that the free surface profile is coherentlyrelated to the position of circumfluence in the mold of continuous casting. With the increase of nozzle port inclination, thepositive vortex above the jet is near to the meniscus and the level fluctuation becomes prominent.

关键词： Level fluctuation, Fluid flow, Continuous casting, Numerical simulation

Modeling of Mold Filling and Solidification in Lost Foam Casting

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Journal of Materials Science & Technology 2003年第5期19卷 395-397页

作者： Fengjun LI, houfa shen and Baicheng LIUDepartment of Mechanical Engineering, Tsinghua University, Beijing 100084, China Dept. of Mech. Eng. Tsinghua Univ. Beijing 100084 China

Based on the characteristics of the lost foam casting (LFC) and the artificial neural network technique, a mathematical model for the simulation of the melt-pattern interface movement during the mold filling of LFC has been proposed and experimentally verified. The simulation results are consistent with the experiments in both the shapes of melt front and filling sequences. According to the calculated interface locations, the fluid flow and the temperature distributions during the mold filling and solidification processes were calculated, and the shrinkage defect of a lost foam ductile iron casting was predicted by considering the mold wall movement in LFC. The simulation method was applied to optimize the casting design of lost foam ductile iron castings. It is shown that the model can be used for the defects prediction and for casting design optimization in the practical LFC production.

关键词： Lost foam casting Numerical simulation Artificial neural network

Study and Application of Mold Filling Simulation of Shaped Castings

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Journal of Materials Science & Technology 1997年第2期13卷 107-112页

作者： Baicheng LIU Wei QIU houfa shen Zhiqiang GAO (Dept. of Mechanical Engineering, Tsinghua University Beijing 100084, China) Dept. of Mechanical Engineering Tsinghua University Beijing 100084 China

In this paper, an algorithm for simulating fluid flow and heat transfer for mold filling of shaped castings is presented. The main features of the algorithm include: 1) a simple but practical technique based on VOF method to determine free surface, 2) an explicit scheme of enthalpy to solve the energy equation more efficiently, and 3) an effective treatment to modify the flux deviation due to pressure iteration. In order to verify these methods, well controlled experiments have been repeatedly done with both water analog and gray iron pouring experiments to record the flow patterns and temperature variations. The calculated results are in accordance with the experimental ones. For the applications, the simulated initial temperature distribution right after mold filling was used to analyse subsequent solidification and to predict shrinkage defects. Actual castings were poured and tested in a foundry plant. The reuslts show that the defects predication with considering fluid flow effects is more precise than that without considering the effects.

关键词： Simulation Study and Application of Mold Filling Simulation of Shaped Castings Mold

IN718高温合金水平定向凝固和真空电弧重熔过程中“黑斑”形成的多组元数值模拟

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稀有金属材料与工程 2022年第11期51卷 4076-4084页

作者：李桐沈厚发清华大学材料学院北京100084

建立了多组元两相模型来描述IN718高温合金凝固过程中的宏观/微观传输和“黑斑”形成,并应用动态网格算法模拟真空电弧重熔(VAR)过程中的填充过程。首先,使用热力学计算方法求解液相成分随固相分数的变化,并获得多组元合金的枝晶间液相... 详细信息

建立了多组元两相模型来描述IN718高温合金凝固过程中的宏观/微观传输和“黑斑”形成,并应用动态网格算法模拟真空电弧重熔(VAR)过程中的填充过程。首先,使用热力学计算方法求解液相成分随固相分数的变化,并获得多组元合金的枝晶间液相密度。之后模拟了水平定向凝固工艺下形成的“黑斑”,并与实验结果进行对比,研究其形成机理和影响因素。最后,利用所开发的模型来研究工艺参数对工业规模VAR铸锭中“黑斑”的影响。结果表明,元素组成对凝固过程中液相的密度变化有显著影响,“黑斑”的形成伴随着高热溶质对流强度。“黑斑”的生长方向由液相密度差和凝固界面相对重力方向的角度决定。在VAR过程中,熔池形状受电极熔化速率和冷却速率影响。

关键词：黑斑宏观偏析数值模拟高温合金真空电弧重熔

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板坯连铸结晶器流场的格子法模拟

机械工程学报 2006年第9期42卷 154-159页

作者：张小军沈厚发清华大学机械工程系北京100084

给出一种与现有传统数值方法不同的计算流体动力学介观模型。在该模型中,建立描述流体微团运动及碰撞规律的格子Boltzmann方程以及平衡分布函数,并依此求解出流体微团的分布函数,而流场的速度、压力等物理量可直接根据流体微团的分布函... 详细信息

给出一种与现有传统数值方法不同的计算流体动力学介观模型。在该模型中,建立描述流体微团运动及碰撞规律的格子Boltzmann方程以及平衡分布函数,并依此求解出流体微团的分布函数,而流场的速度、压力等物理量可直接根据流体微团的分布函数统计求和而得。在此基础上计算了板坯连铸结晶器中心面内的二维流动,模拟出流场在高雷诺数条件下流动模态随时间的变化过程,得到与试验结果一致的流场结构,较真实地反映高雷诺数条件下结晶器内湍流的有漩性、非对称性及非定常性。结果表明随着流场雷诺数的提高,流动中物理量脉动成分的显著增强,打乱了原有对称性的大涡结构,使得流动呈现非对称性及非定常性。

关键词：格子法连铸结晶器 Navier-Stokes 方程湍流

Analysis of solute redistribution and centerline segregation in continuously cast thin slab

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China Foundry 2004年第2期1卷 94-98页

作者： Changwen MA houfa shen Tianyou HUANG Baicheng LIU Department of Mechanical Engineering Tsinghua UniversityBeijing iooo84P.R.China

A model has been built to calculate the solute redistribution in continuously cast thin slab and the effect of the fluid flow in mush on the centerline segregation was analyzed. The corresponding simulation program was developed by applying the SIMPLER algorithm. The momentum, energy and species conservation equations were solved simultaneously. The macro-segregation of a 3-D thin slab with 900 mm × 50 mm cross section was simulated. The obtained results show that negative segregation forms near the slab surface and severe centerline segregation forms in the mid-thickness plane. The species concentration in the centerline of the slab increases obviously at the final solidification stage.

关键词： centerline segregation continuous casting solidification numerical simulation

薄板坯连铸工艺因素对结晶器非稳定流场特征参数的影响

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北京科技大学学报 2008年第7期30卷 800-804页

作者：沈丙振沈厚发清华大学机械工程系先进成形制造教育部重点实验室北京100084

利用波高仪和粒子示踪法在1∶1的水力学模型中研究了薄板坯连铸工艺参数对结晶器内非稳定流场特征参数的影响.结果表明:流场特征参数随时间变化具有一定的周期性.随着拉坯速度增加,平均射流撞击位置下降,平均回流区中心深度下降,平均波... 详细信息

利用波高仪和粒子示踪法在1∶1的水力学模型中研究了薄板坯连铸工艺参数对结晶器内非稳定流场特征参数的影响.结果表明:流场特征参数随时间变化具有一定的周期性.随着拉坯速度增加,平均射流撞击位置下降,平均回流区中心深度下降,平均波高增加;同时,撞击点、回流区中心深度和波高的变化范围增大,周期减小,结晶器内流动不稳定程度增大.随着水口浸入深度增加,平均射流撞击位置下降,平均回流区中心深度下降,平均波高减小;同时,撞击点、回流区中心深度和波高的变化范围减小,周期增加,流场不稳定程度减小.随着水口出口角度增加,平均射流撞击位置下降,平均回流区中心深度下降,平均波高减小;对于较大的水口出口角,尽管结晶器内流场非稳定流动范围较大,但是流场的运动周期较大,液面波动的非稳定程度却较小.

关键词：薄板坯连铸结晶器水力学模拟流场液面波动

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钢锭铸造过程宏观偏析数值模拟

金属学报 2018年第2期54卷 151-160页

作者：沈厚发陈康欣柳百成清华大学材料学院先进成形制造教育部重点实验室北京100084

本文以宏观偏析数学模型在钢锭铸造过程中的应用为主,阐明了宏观偏析的机理及影响因素,归纳了已有的几类宏观偏析模型,介绍了近年来宏观偏析模型的新发展。还介绍了本课题组进行的大型钢锭宏观偏析数值模拟研究工作,包括开发的多元多相... 详细信息

本文以宏观偏析数学模型在钢锭铸造过程中的应用为主,阐明了宏观偏析的机理及影响因素,归纳了已有的几类宏观偏析模型,介绍了近年来宏观偏析模型的新发展。还介绍了本课题组进行的大型钢锭宏观偏析数值模拟研究工作,包括开发的多元多相宏观偏析数学模型在36 t钢锭铸造中的应用,以及多包变成分合浇工艺的数值模拟。对36 t钢锭进行全截面解剖,结果表明,模拟结果与实测吻合较好,进而说明所开发的多元多相宏观偏析模型能够较准确地预测钢锭中产生的宏观偏析。此外,模拟结果显示,多包变成分合浇工艺可得到与凝固后实际偏析形式相反的初始溶质分布,这也证明了多包变成分合浇工艺在宏观偏析控制上的应用能力。

关键词：钢锭凝固宏观偏析数值模拟