应力腐蚀作用下汽轮机转子裂纹扩展及对故障特征影响研究

Large steam turbines are important facilities of nuclear power plants. Steam turbine rotor runs with high speed under corrosion conditions, and their crack faults can bring great pecuniary loss for nuclear power enterprises. Under the influences of light elements from corrosion procedures and applied external load, crack propagtes into the rotor, and the propagation will result in complex forms of fault features of the rotor crack. It is necessary to study the crack propagation under the influences of many factors including rotor material features, crack forms, corrosion, and rotor speed. The studies are very important to understand facult mechanism of the rotor crack and appearances of fault features, and they can improve accuracy rate and reliability of fault diagnosis. The proposal will integrate several new developed modelling and computational techniques into quasicontinuum calculations, and study regular patterns of rotor crack evolution under the multi-factors and their influences on the fault features of rotor crack. They will be revealed for the evolution mechanism of rotor crack under stress corrosion, discussed for the fault features of steam turbine rotors, and obtained for some creative results in fields of studying structures and dynamics behaviors of the rotor systems under complex environments. Hence, based on the study, it will be provided the ideas for fault prediction and identification of the rotor systems. Owing to the successful implementation of this study, the understanding will be deepen for the rotor fault of the nuclear power steam turbines, and it will be helpful in providing theoretical basis for fault diagnosis and safely running of the steam turbines.

大型汽轮发电机组是核电站的重要设备，在腐蚀环境中高速运转的汽轮机转子出现的裂纹故障给企业带来巨大的损失。在腐蚀产生的轻质元素和外加载荷作用下，裂纹向转子体系内部的扩展，导致转子裂纹故障特征呈现出复杂多样的形式。研究在转子材料特性、裂纹形式、腐蚀和转速等多种因素影响下裂纹的扩展行为，对于理解转子裂纹故障机理及出现的故障特征，从而提高转子故障诊断的准确率和可靠度具有重要意义。本项目拟结合多种新发展的建模和计算分析技术，采用准连续介质方法对多种因素作用下的转子裂纹演变规律及其对转子裂纹故障特征的影响进行详细的比较研究，揭示在应力腐蚀作用下转子裂纹演化的机理，探讨汽轮机转子系统故障特征，得到转子在复杂环境中结构与动力学行为演化研究领域的一些创新性成果，提出转子裂纹故障预示和识别的思路。项目的成功实施将深化我们对核电汽轮发电机转子故障的认知，有助于为核电汽轮发电机组的故障诊断与安全运行提供理论依据。

核电站汽轮机转子用钢铁材料的结构与性质是影响在腐蚀环境和转动条件下失效机制的重要因素。材料内的铜元素以及对氢元素等的吸放极大地影响材料的腐蚀特性。本项目从理论计算和试验研究两个方面进行。理论上进行基于经典牛顿力学的计算，实验上设计用于测试吸放氢能力的数字控制式多通道试验装置，并应用现代控制理论于袋式除尘器的设计中。基于经典牛顿力学的计算工作从微观和宏观两个尺度对材料的结构及形状变化等进行研究。对于转子材料的重要组成元素铁的晶体形成过程及其缺陷分布进行了原子尺度上的分子动力学计算，并对影响钢铁材料腐蚀性能的重要组分铜颗粒的结构热稳定性进行了计算。对于大块件，应用叶素动量理论对风力机攻角调节进行改进。在转子工作环境下，雾气、尘埃等直接影响转子的应力腐蚀行为，其中材料的吸放氢能力是影响转子材料腐蚀裂纹的重要因素。研究结果表明，温度变化对于铁基材料和铜颗粒结构的变化具有重要影响，材料内存在空位、间隙原子以及界面等多种缺陷形式。在实验工作中，应用设计的PCT多通道试验装置测试了吸放氢动力学曲线。并在试验中证实模糊温度控制方法和联合清灰机制在袋式除尘器控制中具有良好的效果。研究工作有助于理解转子用材料内缺陷类型、合金元素以及材料吸放氢能力等对材料结构与性质的影响机理，对于转子用材料内的微观结构与使用环境间多种复杂因素之间相互作用机制的认识具有理论意义。