连铸结晶器内氢气/钢液两相非稳态湍流特性的大涡模拟研究

提出了一种连铸结晶器内氩气/钢液两相非稳态湍流流动的大涡模拟模型,采用非齐次Euler-Euler双流体模型描述氩气/钢液两相流运动方程,采用大涡模拟模型对湍流黏性力进行求解.利用板坯探伤缺陷检测结果间接地验证了氩气/钢液两相非稳态湍流运动特征,利用水模型实验结果验证了两相的非对称流动特征.结果表明,氩气泡的行为将直接影响结晶器内钢液的流动行为.气泡在结晶器内的运动行为主要受吹Ar量和钢流量的影响,其平均直径随着吹Ar量的增大而增大,随着钢流量的增大而减小.结晶器内的不对称流场具有不稳定性,偏流是绝对的,对称是暂时的、偶然的,偏流的周期性不明显.结晶器二冷区弯曲段的弧形形状对结晶器内部流场的影响较大,偏流发生在弯曲段附近.     

板坯连铸结晶器电磁控制流动技术

板坯连铸实践表明,结晶器内钢水流动对铸坯质量和产品质量产生重大影响,控制结晶器内钢水流动已成为生产高质量产品和提高生产率的重要技术手段.综述了三类板坯连铸结晶器电磁控制流动(控流)技术的基本内容,对每类电磁控流技术,着重介绍了其配置和电磁力特征、冶金机理和冶金效果及其对最终产品质量的影响等.     

电磁制动下板坯结晶器内金属流动的物理模拟

以水银为实验工质,通过物理模拟考察板坯连铸电磁制动时,电磁场对结晶器内液态金属流动的影响规律。采用超声波多普勒测速仪测量了结晶器上部磁场B1=0、0.18、0.36 T和0.5 T,结晶器下部磁场B2=0.5 T情况下,板坯结晶器(模型)内水银的流速分布,考察了磁场强度对结晶器内及液面处金属流动,及其对结晶器窄壁的冲刷作用等的影响。实验结果表明,板坯连铸时,对于抑制液面波动的结晶器上部磁场应选择较低的磁场强度,而用于实现钢水稳定和形成活塞流的结晶器下部磁场,则应选择高的磁场强度。在本文实验条件下,磁场匹配关系B1=0.18 T、B2=0.5 T时,结晶器内的金属流场较为理想,表现为届时既可控制液面波动,又能使结晶器下部的金属流动基本实现活塞流。     

板坯连铸结晶器内非对称流动对渣钢界面的影响

结晶器渣钢界面的控制是板坯连铸操作中的重要环节。为研究渣钢界面的流体动力学行为,建立了“空气保护渣钢液”三相流模型,运用雷诺应力模型和非均相混合模型对结晶器三相流场进行模拟研究,采用等体积分数法确定渣钢界面的形状及位置。浸入式水口对中不良时会导致结晶器内产生非对称流场,研究发现该流场的渣钢界面波动比相同操作参数下对称流场的界面波动要剧烈得多,且非对称流场的渣钢界面会有偏流甚至旋涡出现,对结晶器操作危害很大。     

电磁制动技术的发展及在板坯连铸结晶器中的应用

总结了板坯连铸结晶器中电磁制动技术的发展、研究状况以及冶金效果。电磁制动技术可以控制结晶器内钢液的流动、稳定弯月面、减少卷渣现象,有利于结晶器内夹杂物的上浮及去除,从而提高铸坯的质量,且为提高铸坯拉速创造了条件。结果表明电磁制动的影响因素有板坯宽度、浇注速度、浸入式水口（SEN）的形状等。     

板坯连铸机结晶器主要参数及结构的优化

在板坯连铸机结晶器设计过程中,选择合适的参数和结构形式,可以改善结晶器的传热效果和受力情况,提高设备性能和使用寿命。从理论和实践的结合上就板坯结晶器主要参数及相关设备结构的优化作了阐述,为板坯连铸机结晶器的设计、研究及生产操作提供了依据。     

板坯连铸结晶器电磁搅拌参数优化数值模拟研究

摘 要：采用数值模拟的方法,对电磁搅拌下板坯结晶器内的流场进行了计算,考察了不同连铸工艺和搅拌电流作用下的流场结构和分布特征,提出了自由液面的卷渣指数（MFEI）和结晶器内流场均匀性指数（VUI）,介绍了上述指数对板坯结晶器内流场电磁搅拌效果的判定方法,进而提出了搅拌参数的综合优化方法。     

电动缸在线热调宽在板坯连铸机上的应用

分析了板坯连铸结晶器在线热调宽装置现有技术产品状况,自主开发了 “板坯连铸结晶器电动缸在线热调宽技术”,并将此技术应用到某钢厂板坯连铸机结晶器上。介绍了该新技术产品的系统组成、工作原理、技术指标、主要优点、动作规则、控制模式,及取得的效果。     

连铸结晶器用铜板的现状与发展

综述了连铸结晶器用铜板材的性能要求及其强化类型。重点分析了各类结晶器铜板的物理性能、力学性能和耐磨性。指出了采用内氧化法制备的氧化铝弥散强化铜合金具有高强度、高导热率和良好的耐磨性等特性,是各种连铸板坯连铸机结晶器铜板材理想的更新换代产品。     

板坯连铸结晶器流场及液面波动水模研究

以我国实际生产的某结晶器为原型,建立1∶1有机玻璃水模型,模拟研究了结晶器断面和中间包液位对板坯连铸结晶器流场形态和结晶器液面波动的影响。中间包液位改变了水口出口的压力从而使结晶器流场和液面波动发生变化。通过实验研究进一步认识了板坯连铸结晶器液面波动及其影响因素,并用以指导高质量连铸坯的生产。     

Optimization of operating conditions and structure parameters of zinc electrolytic cell based on numerical simulation for electrolyte flow

The physical and mathematical model of an operating electrowinning cell was established, and the flow of electrolyte was numerically simulated by the commercial software Fluent. The results indicate that there are two circulations at the surface flow where part of electrolyte backflows to the inlet from the side of cell, and the rest flows directly to the outlet, and the separation of two circulations with opposite direction occurs at the 20th pair of anode-cathode. This phenomenon was observed in the real operation. The electrolyte flows into the space between anode and cathode from the side portion of the cell. Meanwhile, the interelectrode effective flow rate (IEFR) is put forward to describe quantitively the flow field characteristics and is defined as the ratio of electrolyte flow between the anode and cathode to the total flow area. The influences of structure parameters and operating conditions on IEFR, such as the inlet angle, the volumetric flow rate, the inlet position and the height of steel baffles were simulated. The inlet position has a significant influence on the IEFR and its optimal value is 0.9 m below free surface. The inlet angle should be in the range from ?10° to 10°. IEFR is in linear proportion with the volumetric flow rate, and the height of the steel baffle has little influence on the flow field.     

连铸结晶器内钢液涡流现象的大涡模拟及控制

采用大涡模拟方法对结晶器内钢液涡流现象进行模拟,研究了水口插入深度、出流角度等与“湍动涡”在液面停留时间的关系,分析了“湍动涡”和“偏流涡”的形成机理。提出了消除“湍动涡”的平板式涡阻止器结构,对涡阻止器作用下“湍动涡”和“偏流涡”的运动规律进行模拟。数值模拟结果表明：“湍动涡”是由于流体本身的脉动所形成的,随着水口出流角度的增大及水口插入深度的增加,“湍动涡”在液面的停留时间延长;“偏流涡”是由于水口不对中导致的液面的不对称流动以及流体本身的脉动综合作用形成的。平板式涡阻止器能有效消除“湍动涡”,并对“偏流涡”有一定的减弱作用。     

Water hammer in coarse grained solid liquid flows in hydraulic hoisting for ocean mining

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基于CFD的旋流器内流速特征的数值模拟(英文)

为了查清旋流器内流速分布特征及其影响机理,在不同的结构参数和操作参数条件下,对旋流器内流速进行基于CFD方法的数值模拟。结果表明,在旋流器的内旋流和外旋流中均存在非对称的等轴向速度面,而且旋流器锥角和底流口直径对零轴向速度面锥底点的轴向空间位置具有显著的影响。另外,在旋流器有效分离区域内的水平面上存在切向速度的等值线。入口压强对轴向速度分布特征和切向速度分布特征的影响不显著,但可使切向速度及梯度明显增大,致使高密度颗粒向边壁的运动速度加快,从而使旋流分选的作用加强。     

Elucidation of the effect of welding speed on melt flows in high-brightness and high-power laser welding of stainless steel on basis of three-dimensional X-ray transmission in situ observation

This research was performed with the objective of clarifying the effect of welding speed on melt flows during melt-run welding of SUS304 stainless steel plates with a 6-kW power laser beam on the basis of three-dimensional X-ray transmission in situ observation. As welding speed increased from 25 to 250 mm/s, three kinds of welds characterized by porosity formation and no defects or underfilling due to spatters were produced. The average and the maximum values of measured melt flow velocity were 3 and 10 times higher than the welding speed, respectively. Two kinds of circulation flows at the inlet or the tip of a keyhole were confirmed to control heat transfer in a molten pool. It was found that the circulation flows were so sensitive to the welding speed that bubbles resulting in porosity or spatters were often formed. According to X-ray observation of the formation of spatters with tungsten carbide (WC) tracers, as the melt flow rose along the keyhole wall, the velocity was accelerated from 0.24–0.54 m/s near the keyhole inlet. Consequently, the melt flows made the convex surface behind the keyhole grow higher, resulting in spattering.     

Steel pipe corrosion under flow conditions-III. Effect of sulphate ion

Data are presented on the corrosion of commercial iron piping in flowing aerated water containing sodium sulphate (26–470 ppm SO₄^2?) at 125°F as weight loss-time curves for flows, corresponding to Reynolds numbers in the range 21,000–63,000. It was observed that sulphated water produced uniform attack with no pitting corrosion. Increased corrosion always resulted with increased sulphate ion concentration over the flow range considered. Although the sulphate ion was not detectable in the corrosion product layer, its presence in solution significantly altered the physical form and nature, such as roughness, porosity and adhesion, of the corrosion product layer. The double resistance model recently proposed provided a useful basis for assessing the relative resistances afforded by the corrosion product layer and the liquid film or damped turbulence layer. It was found that the mass transfer coefficient in the damped turbulence layer controls the overall mass transfer process for the exposure time, flow rates, and sulphate ion concentration ranges examined.     

湘西山区典型高坡降小流域泥石流特征及其防治措施

高坡降小流域泥石流在湘西山区分布较为广泛,具有高隐蔽性、暴发突然、摧毁能力强等特点.本文以吉首市云华泥石流为例,从泥石流的形成角度,对该流域的地形分区特征、物源条件进行了研究,分析了泥石流的成因机制和引发因素,并根据泥石流的活动特性提出了包括岩土工程和生物工程的"固源+分级拦挡+排导+监测"的综合治理体系.该方案可达到...     

Flow equation and similarity criterion during centrifugal casting in micro-channel

Liquid metal filling flow process in the microscale during the centrifugal casting process was studied by means of similar physical simulation. The research was focused on derived similarity criterion. Based on the traditional flow equations, the flow equation and the Bernoulli's equation for liquid metal flows in micro-scale space were derived, which provides a mathematical model for numerical simulation of micro-scale flow. In the meanwhile, according to the micro-flow equation and the similarity theory, the similarity criterion for the physical simulation of the mold filling behaviors was presented under centrifugal force field, so as to achieve the visual observation and quantitative analysis of micro-flow process.     

电磁驱动熔体流动与枝晶变形断裂模拟

建立了电磁离心凝固过程熔体动量传递、传热和传质耦合数学模型，模拟计算了熔体在不同感应强度下的流动速度。计算结果表明，熔体在电磁力的作用下产生与铸模转动方向相反的流动，流动速度呈周期性分布，并且在凝固前沿达到最大，随着磁感应强度的增加，熔体流动速度达到的最大值也愈大，使用有限元软件ANSYS，把熔体流动计算结果作为参数，计算了枝品的受力状态，通过计算表明，熔体流过枝晶会在枝晶周围产生很大的速度变化，流体对枝晶的冲刷可使枝晶产生机械折断，电磁搅拌通过增加断裂枝晶数量促进柱状晶-等轴晶转变。     

现代机械系统设计中的信息流设计研究

分析了机械系统中的信息、信息流特点以及信息流结构模型,从单机机械系统、生产线机械系统以及机械系统的组成等方面分析丁现代机械系统没计中的信息和信息流,说明了信息流设计在现代机械系统设计的重要地位。