【作者】 任庆民；

【导师】 徐鸿；

【作者基本信息】 华北电力大学（北京） ， 热能工程， 2003， 硕士

【摘要】 汽轮机组动静间的轴向碰磨问题是制约机组快速启动和安全运行的一个重要因素。如果能比较准确地计算出汽缸和转子各级处的膨胀量，就可以在线监测动静间隙，这对加快机组启动和提高机组运行的安全性都有重要意义。由于汽缸形状的复杂性，过去常采用质面比[1]或汽缸及法兰刚度系数方法[2]对汽缸轴向膨胀进行估算，这些方法不仅计算繁琐，而且精度较差。比较客观地反映汽缸膨胀，还可采用有限元软件进行离线分析，但通过传热和变形分析建立蒸汽温度变化和轴向变形的理论模型进行数学模拟还未见到相关报道。本文提出了一种汽缸膨胀的近似算法，为实现汽缸动静间隙的在线监测提供了一种较为准确计算模型。为了计算汽缸热膨胀，本文在大平板非稳态导热基本理论的基础上，提出了已知初始温度分布，环境温度不断变化时，大平板导热规律的一种近似算法，作为汽缸热膨胀计算的理论基础。在计算汽缸膨胀时，先将汽缸沿轴向分成若干段，分别计算各段膨胀量，然后累加。计算各段膨胀量时，定义了膨胀特征温度，用以表征其热膨胀能力。整个理论分析的结果都用有限元进行了验证，结果吻合较好。为了将该理论应用于实践，并在实践中接受检验，笔者在理论基础上设计了一套汽缸各级膨胀监测系统。通过与热力计算模块和转子膨胀计算模块的连接后，构成了一套机组胀差在线监测系统。该系统通过一段时间运行，结果比较满意。这说明该理论成功的经受了实践检验，有实际应用价值。针对有限元法使用复杂，可移植性差的特点，本文提出了可视化热分析的思想，即在保证一定精度的前提下，尽可能使分析过程直观、简便。所谓可视化热分析，是指用户通过输入参数，构建基本的形状模块，通过将若干模块连接在一起构成一个实体，然后在实体上施加各种边界条件，最后通过计算，将结果以图形、表格的形式显示出来。<WP=3>根据这一思想，笔者设计了一套汽缸温度场，热应力，热膨胀的可视化分析软件包。该软件包界面友好，操作简单，分析结果精度较高更多还原

【Abstract】 The friction between dynamic and stationary parts of steam turbine unit is an important factor that restricts the fast start up and safe operation of turbine. If expansion at different stages of turbine casing and rotor can be calculated accurately, the cleft between dynamic and stationary parts can be monitored online. It is useful to speed up start up of the unit and it helps improve the security of the unit operation.As a result of the complexity of turbine casing shape , it used to estimate the axial expansion according to the ratio between weight and area of turbine. Those kinds of methods are complex but the result is not very precise. Off-line analysis using finite element software is used to reflect heat expansion of turbine casing precisely. So far, it has not been reported that mathematical simulation is used to analyze the connection between temperature change and axial deformation based on heat transfer and heat deformation theory. In this paper a proximate method is invented to calculate heat expansion of turbine casing, which makes it possible to monitor the cleft between dynamic and stationary part of turbine precisely.To estimate heat expansion of turbine casing, this paper presents a new method to calculate temperature distribution of flat when initial temperature distribution is available and environmental temperature is constantly changing, which is based on classic transient heat conduction. Based on different geometrical shape the casing is divided into several parts, heat expansion of which is calculated respectively. Expansion reference temperature (ERT) is defined to describe the capability of each part. A good coincidence comparing the theoretical result calculated according to the new method presented in this paper with finite element calculation can be observed.<WP=5>A system of monitoring stage expansion is designed to put the theory into practice. So it can be tested by practice. Through combination with thermodynamic and rotor model, a online monitoring system is formulated to calculate expansion difference of the unit. After a period of trial operation it proved to be satisfactory. So the theory is correct and valuable.In the paper a new concept, visual thermal analysis ,is created to solve the problem that finite element analysis is complex and can’t be transplanted easily. In other words the analysis process is intuitivism and simple to the most degree so long as precision of the analysis can be assured.So called visual thermal analysis means that users can set up an entity by linking different models which are established based the parameters input by users. And boundary conditions are added to the entity. After the calculation the final result is displayed in form of diagram and table. Based on the theory above a software package is designed to calculate casing temperature field, thermal stress and thermal expansion. The interface of the software is friendly. It is easy to operate and the result of the analysis is accurate更多还原