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1、上海交通大学 硕士学位论文 热轧钢板层流冷却过程的实验研究与数值模拟 姓名：王永鲲 申请学位级别：硕士 专业：航空宇航推进理论与工程 指导教师：王平阳 20080201 上海交通大学硕士学位论文 热轧钢板层流冷却过程的实验研究与数值模拟 I 热轧钢板层流冷却过程的实验研究与数值模拟 热轧钢板层流冷却过程的实验研究与数值模拟 摘 要 目前，全世界每年生产的钢材中约有 30%需要经过热轧形成板材， 而热轧板材的性能取决于热轧后的冷却过程，即冷却速率和钢板温度的 均匀性。因此，轧后控冷技术是钢铁工业中最重要的流程之一。虽然上 世纪 80 年代开始应用的轧后控冷技术，尤其是近 10 年来才大量应用的
2、层流冷却技术，已经大大提高了生产效率、降低了能源消耗，但其冷却 能力的适应性、钢板内外温度的均匀性以及卷曲温度的准确性都远未达 到人们的预期，并在实际生产过程中经常出现钢板翘曲、应力不均等问 题，尤其对于中厚钢板更为严重。改善轧后控冷技术的关键在于深入理 解过程参数对冷却过程的影响，从而根据钢板材料和所要求的性能等， 准确控制过程参数。然而，由于层流冷却过程中的瞬态冲击沸腾换热相 当复杂，钢板表面温度变化速率高达 2100C/s，并且影响因素众多，对 其开展深入而系统的研究显然具有一定难度。 本文针对轧后控冷中的层流冷却过程，设计并搭建了较为通用可行 的实验台。要想准确获得高温（800C）高冷
3、却速率（1200C/s）条件下 的测点温度，首先需要对热电偶的选取和埋置方法进行详细研究。这里 选用镍镉-镍硅热电偶，利用“通孔/沉孔/盖片”方式埋置热电偶，结合 NI 的高速数据采集系统及 Labview 平台获得冷却过程中钢板内部距离上 表面 0.8mm 处的温度瞬变特性。 针对多种关键影响因素， 如冷却水流量、 管嘴直径、管嘴数量以及管嘴距离钢板表面的距离等，进行了较详细的 实验。之后，建立了导热反问题模型以及三维非稳态有内热源的导热正 问题模型，采用 Fortran 语言编制了相应的计算代码。反问题的计算结果 上海交通大学硕士学位论文 热轧钢板层流冷却过程的实验研究与数值模拟 II 采
4、用简化的理论解进行验证，反问题则采用给定对流换热系数的正问题 计算所的温度作为输入，而反演得到的对流换热系数与前面给定的数值 进行比较。验证结果表明本文所建理论模型和编制的计算程序具有一定 的可信度。利用导热反问题程序结合实验测量结果反演测点所对应壁面 点的温度瞬变特性、对流换热系数以及壁面点的热流密度。从而为分析 所考察参数对冷却过程的影响提供了完整的技术路线和平台。进而，利 用正问题程序结合反演的对流换热系数以及钢板表面的分区技术，获得 钢板内部所有位置的温度瞬变特性。研究结果表明，钢板表面不同位置 的温度瞬变特性差别很大；随着撞击速度和撞击区域的增大，钢板内部 温降增快，但多股水流的交会
5、区域以及撞击区内的对流换热系数变化不 大。本文的计算路线和研究结果可以为实际生产中层流冷却过程控制提 供参考依据。 关键词：中厚板，热轧，层流冷却，实验，数值模拟 上海交通大学硕士学位论文 热轧钢板层流冷却过程的实验研究与数值模拟 III EXPERIMENTAL STUDY AND NUMERICAL SIMULATION OF HOT STEEL PLATE LAMINAR COOLING ON THE RUNOUT TABLE ABSTRACT Approximately 30% of steel are hot-rolled to flat products annually in t
6、he world. The properties of hot-rolled flat steel is decided by the subsequent cooling process, these are the cooling rate and the uniformity of the temperature. Therefore, controlled cooling on the runout table is one of the most important processes in the steel industry. The controlled cooling aft
7、er hot-roll which is began to be used in the last 80s, especially widely used laminar flow cooling technology in recent decade, have greatly improved the efficiency of production and reduced consumption of energy resource, but the adjustability of the cooling capability, the uniformity of the temper
8、ature distribution in the plate and the veracity coiling temperature are far from the expectation. Plate warp and poor stress uniformity are often encountered in actual production, and even worse for middle and heavy steel plate. The key to improve controlled cooling technique understands the affect
9、ion that process factor to cooling, according to the material of steel plate and the properties desired, control the process factors veraciously. However, the instantaneous impingement boiling heat transfer in laminar cooling is rather complicated, the temperature rate at the plate surface reaches a
10、s high as 2100C/s, and it is influenced by many factors, it is difficult to develop a deep and systemic research. In this article, a universal experiment table is designed and built to study the laminar cooling process. In order to obtain accurate temperature data of high temperature and high coolin
11、g rate, it is the first step to choose thermocouple and fix the thermocouples. In this article, K type thermocouple was selected and they are fixed by a through 上海交通大学硕士学位论文 热轧钢板层流冷却过程的实验研究与数值模拟 IV aperture-groove-cover method. A set of NI high speed data system and Labview are employed to obtain th
12、e temperature 0.8mm under surface. Detailed experiments are carried out to study some key factors such as water rate, nozzle diameter, number of nozzles and the distance from the nozzle to plate. An inverse heat conduction model and a 3-d unsteady heat conduction model with inner heat source were de
13、veloped, and corresponding code was programmed by FORTRAN. The results of computing program are checked. Surface temperature of test points and heat transfer coefficient(HTC) as well as heat flux at surface are worked out by inverse heat transfer program align with experiment data, which provides in
14、tegrated information for the study of the affection of factors to the cooling process. Further, at the base of 3-d unsteady heat conduction program and heat transfer coefficient, it is easy to get the temperature field of the whole plate. The result shows that the temperature change is quite differe
15、nt in different location. The temperature drop in the plate rises with the increase of impingement velocity and size. But the HTC in the cross zone of several jets and impingement zone hardly changes. The computing route and research result provide reference to the control of laminar cooling in actu
16、al production. KEY WORDS: heavy steel plate，hot rolling, laminar cooling, experiment, numerical simulation 上海交通大学上海交通大学 学位论文原创性声明学位论文原创性声明 本人郑重声明：所呈交的学位论文，是本人在导师的指导下， 独立进行研究工作所取得的成果。除文中已经注明引用的内容外，本 论文不包含任何其他个人或集体已经发表或撰写过的作品成果。 对本 文的研究做出重要贡献的个人和集体，均已在文中以明确方式标明。 本人完全意识到本声明的法律结果由本人承担。 学位论文作者签名：王永鲲 日期：2008 年 3 月 17 日
