【作者】 王仕博；

【导师】 王华；

【作者基本信息】 昆明理工大学 ， 冶金能源工程， 2013， 博士

【摘要】 随着现代冶金工艺的发展,大们迫切需要了解和描述冶金过程中存在的各种流体流动现象。但冶金工业的高温环境使得直接测量存在很大困难,难以获得足够可靠的流场信息和数据。计算流体力学(Computational Fluid Dynamics)是近代流体力学、数值数学和计算机科学相结合的产物,数值模拟和计算机实验是其基本特征。随着计算机技术和相关软件的飞速发展,CFD技术为深入研究冶金过程中流体流动现象提供了一种新的方法和可能。富氧顶吹强化熔炼技术的核心是通过顶吹喷枪的浸没式搅拌实现熔池内三相间的快速传热传质过程,从而取得显著的节能减排成效。但一味强调高强化熔炼将导致熔炉炉衬寿命低、喷枪等关键设备磨损严重,不当的吹喷操作甚至会引起泡沫渣等严重事故。因此利用CFD技术对熔池熔炼喷吹搅拌的传热传质过程进行数值模拟研究,探讨喷吹速度、深度对熔池内流型的影响以及熔池喷溅对炉壁的破坏作用是十分必要的。本文以云南省A公司铜艾萨炉顶吹熔池热态搅拌过程为研究对象,主要从计算流体力学模拟仿真以及水模型实验两个方面进行了以下几方面的研究工作：首先通过在VOF理论框架中综合考虑了两相表面张力和壁而函数的影响,实现了单气泡在粘性流体中的自由上浮、单液滴自由下落冲击自由液面、多气泡在液面下的上浮及融合等非稳态三维数值模拟和水模型实验；在此基础上,利用RNG型κ-ε双方程模型和Geo-Reconstruct几何重构法实现了两相界面上的非稳态流动与传热的耦合,建立起二维顶吹熔池的多相流流动一传热耦合模型,得到顶吹气泡长大、上浮及破裂等行为对搅拌效果的影响规律；最后将以上二维顶吹模型拓展至三维空间,结合高质量的三维艾萨炉炉体网格,建立等比例艾萨炉浸没式顶吹熔池的热态数学模型,得到艾萨炉三维顶吹热态熔池的温度场、流场等计算结果,对比了流量及喷枪插入深度对熔池搅拌效果以及炉内温度场分布影响,得到对实际生产具有理论指导意义的优化操作参数。通过以上模拟及实验研究,从多相流流态角度完成水下气泡自由上升的形变机理分析,认为气泡上下表面压力差与气泡边界共同作用下产生的向上的射流是导致气泡发生底部凹陷形变并最终分裂的主要因素,从仿真模拟和水模型实验两个方面得出单气泡自由上浮的速度变化和形变规律。将本文的各工况的边界条件及计算结果进行无量纲处理,经归纳总结发现：在中等的雷诺数范围(5<Re<100)和比较高的邦德数(20<Bo<50)下,气泡底部基本是凹陷形态的;观察气泡的底部,发现雷诺数越低,底部边缘越圆,而随着雷诺数的增加,边缘变得尖锐起来。在艾萨炉堂内,顶吹气流量对熔池搅拌效果以及炉内温度场分布影响的敏感度要大于喷枪插入深度的影响。大流量对熔池的搅拌更剧烈,炉膛内温度上升得比较均匀。而喷枪插入深度加大会引起靠近壁面的温升加快,炉膛内中心与近壁面区域的温度分布相差较大,不利于延长炉衬寿命,因此大流量、较浅的插入深度有利于取得最佳的搅拌效果。考虑到本文的计算过程没有包含气泡在高温下的瞬间膨胀现象所带来的巨大搅动能,综合生产实际和理论计算结果,艾萨炉喷枪最佳气体流速应控制在12-15m/s,插入渣层深度与熔池深度的比应控制在0.03～0.08之间。对于本文所得到的三维非稳态的流动、传热耦合计算结果说,关键截而物理量的加权平均值及标准方差值同三维立体物理场结合分析的方法仃助于更准确地描述模拟过程所反映的规律性。等值面与特定截面物理量加权平均法可作为判定三维瞬态多相流混合程度的评价方法。更多还原

【Abstract】 With the development of modern metallurgical craft, people need to understand and describe all kinds of fluids flow’s phenomenon during the metallurgical course urgenly. But it is difficult to measure directly for high-temperature environment in metallurgical industry, and get enough information and data about flowing field reliably. Computational Fluid Dynamics is the product which combine with Modern Hydrodynamics、Value Mathematics and Computer Science, its essential feature is numerical simulation and computer experiment. With the rapid development of computer technology and relevant software, CFD technology have offered a new method and possibility for research fluid flow phenomenon in metallurgy process thoroughly.Core strengthening smelting technology of TSL is the rapid process of heat and mass transfer through immersion top blown lance stirring bath three phases, so as to achieve significant energy-saving effect. But blindly emphasizes high intensified smelting will lead smelting furnace lining life of low, spray gun and other key equipment wear, improper injection operation even serious accidents caused by the slag foaming. Numerical simulation study on heat and mass transfer process and the use of CFD technology to the molten pool smelting blowing stirring, to investigate the effect of injection speed, depth of the bath flow and bath splash damage to the furnace wall is very necessary. In this paper, taking A company of Yunnan copper lsasmelt furnace top blown bath hot mixing process as the research object, mainly from the two aspects of computational fluid dynamics simulation and water model experiment was carried out to study the work of the following aspects:First, through in the VOF theory framework of two phase surface tension and wall function is considered, to achieve a single bubble in a viscous fluid, free floating single droplet free falling impact free surface, three dimensional numerical simulation of unsteady multi bubble floatation and fusion in the liquid, and the results are verified with the classical literature and the water model experiment phenomenon, for further study of bubble laid solid foundation in the process of strengthening stirring strong nonlinear behavior rules. After completing the above simulation behavior of single bubble and single of droplet, using the RNG κ-ε model and Geo-Reconstruct geometry reconstruction method to achieve the coupling unsteady flow and heat transfer of two-phase interface， establish two-dimensional top blown bath of multiphase flow and heat transfer coupled model, and compare the results with the classic paper and water model experiment phenomenon was verified, and obtains the influence law of top blowing bubbles, floating and fracture behavior of the stirring effect; The above two top model is extended to3D space, combined with3D ISA furnace body mesh with high quality, building thermal model top blown bath ratio ISA submerged, using the QUICK discretization scheme and based on the pressure implicit splitting operator (Pressure Implicit with Splitting of Operators) pressure velocity coupling scheme to ensure stable and convergence process, get ISA3D blown hot bath temperature field, flow field calculation results, compared to the flow rate and nozzle depth mixing effect and the temperature field in the furnace the effect of the distribution of the bath, get the optimization of operating parameters with theoretical guidance for practical production;From the angle of multiphase flow deformation mechanism of bubble free finish rising water, that the difference between the upper and lower surface of bubbles and bubble boundary under the action of the upward jet is the main factor leading to bubble bottom sag deformation and eventually split, the changes of velocity and deformation rule of the single bubble free floating from the two aspects of the simulation simulation and water model experiment. The condition of the boundary conditions and calculation results into the corresponding dimensionless number, the summary of findings:in the middle range of Reynolds number (5<Re<100) and relatively high Bond number (20<Bo<50), the bottom is the basic form of the depression of the bubble; bubble bottom observation, found that the Reynolds number is low, the bottom edge of the circle, and increases with Reynolds number, edge sharpened up.The effects that the quantity of flow affects the temperature distribution are more sensitive than gun insertion depth. Large flow stirring on the bath is more intense, the temperature rise was more uniform way in bore. While the nozzle depth increase can cause the near wall temperature rise speed, road bore center and near wall region of the temperature difference between the larger, is not conducive to prolong the life of furnace lining.For the calculation of unsteady three-dimensional flow, heat transfer, the key section of physical quantity weighted average value and standard deviation of the same three-dimensional physical field combining with the analysis method helps to more accurately describe the regularity reflected simulation process. The equivalent surface and the specific section physical quantity weighted average method can be used to determine the three-dimensional transient multiphase flow evaluation method of mixing degree.更多还原