电磁制动对薄板坯连铸结晶器涡流的影响

开发了数学模型,以研究电磁制动(EMBR)对薄板坯连铸结晶器涡流的影响。结晶器内熔融钢水由结晶器浸入式水口(SEN)的两个侧孔流出。采用低雷诺数k-ε紊流模型计算有效粘度。数学模拟表明,即使在水口外形对称和注流稳定的条件下也能产生非对称的涡流。模拟中的非对称流动由数据冗余引起,数据冗余代替了实际生产中的水口堵塞、水口不对中和随机湍流等。涡流强度取决于由水口出流角和拉速决定的结晶器表面流速。施加静态磁场可以显著抑制涡流和改变涡流形态,但不能将其彻底消除。表面流速随线圈电流的减小而显著降低,同时结晶器内的波高明显变小。此外,浸入式水口附近由涡流引起的失稳区逐渐变得稳定。结晶器下部的下降流流速受到抑制并形成活塞流。

Implementation and validation of a volume-of-fluid and discrete-element-method combined solver in OpenFOAM

Numerous gas-liquid-solid flows exist in chemical engineering and metallurgical processes. Numerical modeling is an important topic that can be used to improve the design and investigate the operating conditions of these processes. The complicated interphase interaction within such three-phase systems, which include free surfaces and discrete phases, poses challenges in the existing methods. We imple- mented a volume-of-fluid （VOF） and discrete-element-method （DEM） combined solver, which should be useful for modeling the gas-liquid-solid systems, within the OpenFOAM framework. The Du Plessis and Masliyah drag force, added mass force, and capillary force were considered for fluid-particle coupling. The VOF-DEM solver was tested in three different cases, namely, particles in pure gas, particle collision in water, and gas-liquid-solid three-phase dam break. The results were validated against previous experi- ments and good agreement was obtained between the simulations and the experiments, which indicates the accuracy and suitability of this VOF-DEM solver for gas-liquid-solid systems.

电渣重熔H13模具钢过程碳偏析的模拟研究

宏观偏析现象普遍存在于电渣重熔钢锭中,严重影响钢锭的均质性和凝固质量。建立了电渣重熔H13模具钢的三维瞬态耦合模型,对碳偏析现象进行模拟研究,并考虑合金元素间的相互影响。采用各向异性多孔介质模型模拟糊状区的动量衰减,Lever算法计算溶质再分配行为。模拟结果表明,碳元素富集在熔池底部,且随钢锭凝固而增多。重熔钢锭底部和边缘呈负偏析,中心和上部呈正偏析。在其他初始元素一定时,硅初始质量分数由0.8wt%增大至1.2wt%,碳元素正偏析指数增大了8.57%;钼初始质量分数由1.1wt%增大至1.75wt%,碳元素正偏析指数下降了1.89%,并且增加硅、钼元素初始质量分数可以使碳元素分布变得更为均匀;工作电流由3700 A降低至3100 A,重熔钢锭碳含量正偏析指数由0.0856降到0.0837,下降2.22%。