基于热-结构耦合分析的盘式拉杆组合转子动力学特性研究

Gas turbine is honoured as the jewel on royal crown of advanced manufacturing industry and also is a symbol to evaluate the advanced manufacturing level of a country. Because the demand of quickly start-up and shut-down decides the structural feature of rotor in gas turbine, at present, the disk-rod-fastening combined rotor systems are adopted in most heavy-duty gas turbines. The particular structure of this rotor system makes their structural integrity and dynamical performances are easily affected by many factors such as vibrations, impact, noise, friction, fatigue induced by severe working conditions of high temperature, complex flow, heavy load, et al. For this type of rotor system，the nonuniform temperature distribution during operation will result in severe vibration and threat the safety operation of whole gas turbine. Because of the structural complexity of combined rotor system and the foreign blockade on new techniques to us, our country has not gotten hold of the systematical theory and method of design on heavy-duty gas turbine. .Aiming at the independent design of disk-rod-fastening rotor and avoidance the thermal vibration of heavy-duty gas turbine, this project studies the effects of nonuniform temperature distribution and the modes of start-up, shut down, slow roll, cooling etc. on the thermal deformation and dynamic performances. The relationships among heat effect, preload of rods and contact effect between interfaces and even their effects on the structural integration and vibration response of combined rotor are revealed. By applying the basic solutions of segment-combined rotor, considering the thermal effects, rod preload and contact interfaces, the thermal-structure coupling dynamic analysis theory and method of composite rotor system are presented. The thermal vibration mechanism of combined rotor system is deeply revealed combining the theoretical and experimental studies. Aiming at reducing the thermal vibration and probability of crash and rub between rotor and motionless parts, the design criterions are proposed. It will help the autonomously research and development of heavy-duty gas turbine in our country. Moreover, the study of this project is very important to provide the supports of basic theory, method and application technology for fault forecasting and independent design of heavy-duty gas turbine of our country.

盘式拉杆组合转子作为现代重型燃气轮机的重要部件，工作中因温度分布不均衡，会导致系统振动加剧，威胁到整个机组的安全运行。由于此类转子系统结构的复杂性和国外的技术封锁，我国尚没有掌握系统的燃机设计理论和技术。本项目从重型燃机周向拉杆转子的自主设计出发，以避免机组热振动故障为目的，研究不均匀温度分布和启停机、盘车、冷却方式等对组合转子热变形及动力特性的普遍影响规律；揭示热变形、拉杆预紧力、界面接触刚度间的相互关系以及它们总体对组合转子结构完整性及振动响应的影响规律，提出综合考虑热效应、 拉杆预紧力和界面接触效应的组合转子热-结构耦合动力学分析方法；结合实验验证，深入揭示盘式拉杆组合转子系统的热动力特性。从减小热振动和碰磨概率层面考虑，提出机组结构和工作方式的设计准则，为机组故障预测及我国重型燃气轮机的自主设计提供基础理论、方法和应用技术支持。

组合转子是重型燃气轮机和航空发动机转子常用的结构形式，通常服役于高温严酷环境。对具有非连续性结构和复杂热场环境的组合转子，研究其结构强度和动力学特性是保证燃气轮机稳定运行的关键内容之一。本项目以我国自主研发的重型燃气轮机实证机组为背景，研究了温度场对组合转子结构强度和系统动力学行为的影响。. 本项目研究工作进展顺利，按计划完成了研究任务。主要研究成果有：.1. 建立了考虑接触的重型燃气轮机周向拉杆组合转子的热-结构耦合三维有限元分析模型，对组合转子在稳态-停机-盘车-启动-稳态的一个典型工作循环及静置自然冷却过程进行了三维热分析，得到了对应工作方式下组合转子的温度场。.2. 揭示了温度场对拉杆组的最大等效应力、拉力分布和组合转子盘间接触应力分布的影响规律。结果表明拉杆与轮盘或轮盘间的相对热膨胀在组合转子中产生附加轴向力和附加弯矩，其中稳态和静置温度场使拉杆发生松弛、盘间接触应力降低且分布不均匀性加剧，冷启动温度场引起的拉杆拉力、最大等效应力及盘间接触应力分布不均匀性增幅最大。给出了对盘间接触界面和拉杆预紧力的安全裕度设计有益的结果。.3. 综合考虑接触局部分离、粗糙度及拉杆附加刚度等因素影响，提出了一种基于轴向刚度系数的接触刚度计算方法，研究了温度场引起的附加轴向力和附加弯矩对接触刚度的影响。根据温度场引起的附加轴向力、附加弯矩以及弹性模量退化，建立考虑盘间接触效应的组合转子运动方程，分别对组合转子进行了固有频率分析。结果表明：热附加弯矩引起轮盘接触面分离时，组合转子的固有频率大幅降低且振型出现不光滑拐点。.4. 通过有限元仿真验证了理论推导的转子热弯曲变形表达式，并应用该解析表达式研究了静置自然冷却过程中重型燃机组合转子热弯曲变形规律，给出了最小允许盘车时间和最大允许轮盘温度与热弯曲变形值的关系式。结果表明热弯曲变形解析解是研究组合转子盘车策略及热弯曲振动响应的一种高效方法且为实际工程盘车提供了重要理论参考。.5. 搭建了组合转子热振动测试实验台，开展了组合转子稳态及自然冷却实验，分别测得了组合转子在室温、稳态、自然冷却等不同温度条件下的振动响应与轴心轨迹，验证了组合转子热振动相关计算方法的有效性。