【作者】 周英；

【导师】 钟掘；

【作者基本信息】 中南大学 ， 机械设计及理论， 2007， 博士

【摘要】 铸嘴型腔是形成铸轧铝熔体流场温度场的决定因素。形态好的流场和温度场,是生产高质量铸轧板、提高生产效率的必要条件。本文根据铸轧板几何形状结构要求推导了相应的铸嘴流场和温度场应当具备的形态为:板宽方向上流速应几乎相同,考虑到宽展,两个边部流量可略多一些;中、边部的温度差异刚好使得液穴区的最前沿在保证轧制量的波动范围以内,根据轧辊两侧的冷却能力优于中部,所以铸轧板两侧的温度可以略高于中部。本文根据现场实验数据,用计算机辅助工程分析软件ANSYS建立了铝铸轧型腔的模型,模拟各种常见的实际应用过的铸嘴型腔形态,进行了流热耦合分析,使用MATLAB软件对提取的数据进行精确后处理,选取前箱及铸嘴的中间平面、铸嘴的出口平面和出口中线位置作为重点分析部位。通过分析两次现场实验的单分流块与双分流块铸嘴模型以及历次实验的累积数据,推导出了流场与温度场的量化设计参考指标,首次提出了用速度和温度相乘的tv值作为新的流热耦合评价体系的评价指标,并应用到本论文的所有模型中。通过分析空腔铸嘴结构与出口场的关系,揭示了影响出口场状态的几何因素依其影响排序为:在相同尺寸前箱与液面高度的条件下,型腔出口开口度对流场和温度场的影响最大,其次是出口宽度(沿板宽方向度量),再次是进口开口度。通过分析四种常见铸嘴型腔中分流块的作用——水滴型、3C型、偃月型和九块型,在常规到快速的三种出板速度下进行运算,结果显示速度越高,由分流块造成的出口速度温度的突变点附近的不均匀趋势也越明显,说明在常规速度下能满足条件的型腔,到了快速时却不合格,是因为常规时本就存在的不均匀状态,只是到了快速时才凸显出来,因此快速铸轧对流场的温度和速度的设计要求应更加严格。优化设计针对3C型铸轧机的铸嘴型腔进行,分析表明:3C型腔应有居中布置的分流块,其尾端距离出口位置越远,对出口流场的不均匀程度改善越好,分流块其他几何参数需要进行匹配,才可得到优化结果。更多还原

【Abstract】 Shaped nozzle cavity is main element to form the fluid and thermal field. Good fluid and thermal field are necessary to produce high quality the aluminium roll casting strip and to improve production efficiency. This issue derivates the best form of fluid and thermal field: the flow speed at outlet of nozzle distributing along the latitude direction of roll casting strip should be almost the same; the temperature of the two sides and the middle of outlet should differ between the two limits of, and temperature of the middle should be a little lower than that of either side.According to data of reality experiments, the fluid fields of the front-box and the nozzle cavity of aluminum roll-casting are performed by using coupled fluid-thermal FEM simulation of the FLOTRAN module of the general finite element analysis software, ANSYS. Based on the post-processing function of ANSYS and MATLAB, the advanced result analysis was conducted. The mid-plane, outlet plane and midline of outlet are chosen to be the emphases of analysis.This study infers quantified design reference standard for fluid field and thermal field by analyzing the nozzle models of single and double spacers conducted in two on-the-site experiments and data accumulated in past experiments, and further initially claimed that the "tv" value which is resulted from velocity multiple temperature as a new evaluation indicator for the coupled fluid-thermal analysis evaluation system. These indicators have also been used in all models in this study.By analyzing nozzles without spacer, we can make sure the effect degree of the geometrical factors constructing the nozzle cavity are: under the same size of front-box and the level of liquid, aperture width of nozzle outlet has the most effect to fluid and thermal field of model, and length of outlet (along the latitude direction) and aperture width of nozzle entrance are the second and third respectively.Experiments were conducted using four ordinary kinds of nozzle cavity, such as water-drop-spacer shape, 3C shape, crescent-spacer shape and nine-spacer shape respectively, calculating under three drawing-sheet speeds varied from the low to high. The uneven distribution exists in regular status outstands in higher speed. So it is recommended a stricter requirement to the design of temperature and velocity of fluid field.The analysis of furthur optimization design of the nozzle cavity of 3C shape indicated that an improved result would be attained by using middle spacer with it’s tip getting farther from outlet, and good match of geometric parameter of spacers.更多还原