间隙型自带冠叶片转子系统的跨尺度碰撞减振机理与动力学耦合效应研究

As the turbine generator unit toward the direction of high performance, large capacity, its rotor system is used in supercritical and ultra-supercritical high flexible mode. Compared with other types of blade, the vibration coupling effects between integral shrouded blades with clearance and rotor are more evident, and some nonlinear factors such as bearing oil film properties, air exciting vibration, sealing fluid exciting on the dynamic performance of the system are also increasingly significant. Therefore, the blade, wheel disk, shaft and bearing should be considered as a whole, and the vibration coupling effects between blade and rotor should be analyzed comprehensively, and the dynamic characteristics of the system should be studied in the whole. Based on the system structure and application, theoretical analysis, numerical calculation and experimental research methods are taken to study all the problems. The interaction mechanism considering the contact parameters both on the macro and micro scales, the contact interface behavior and interaction mechanism of the flexible structure is analyzed and the practical dynamic model including oblique collision between friction surfaces is put forward. And then the blade root contact algorithm considering blade geometric nonlinear deformation, blade root-wheel rim nonlinear contact friction is designed, the nonlinear dynamic model of the blade-rotor system under multifactors is established, and the impact vibration behaviors of the whole circle blades, the nonlinear motion and its evolution and the effects of nonlinear fluid factors on the blade-rotor coupling system are research comprehensively and thoroughly. Finally, a set of methods and technique modes are summarized, which is demonstrated for a certain steam turbine design and manufacturing.

现代汽轮机转子系统常处于超（超）临界的高柔性状态下运转，与其它类型叶片相比间隙型自带冠叶片与转子之间的振动耦合效应更加突出，油膜力、间隙气流力、密封激振力等非线性因素对系统动力学特性的影响也愈发显著。因此应将叶片、轮盘、转轴和轴承看成一个整体,全面地分析叶片与转子之间的振动耦合效应，从整体上研究系统的动态特性。本项目拟综合利用理论分析、数值计算和试验研究手段，跨尺度分析考虑叶片冠间接触面参数、接触面运动情况和结构柔性的相互作用机理，提出接近工程实际的含摩擦平面斜碰撞的动力学计算模型，设计考虑叶片变形几何非线性、叶根和轮缘接触摩擦非线性的叶根接触算法，构建多因素耦合作用下的系统非线性动力学模型，研究整圈叶片碰撞振动过程、系统非线性运动模式和演化过程、非线性流体因素对叶片转子耦合系统的影响规律等，最终总结出一套支持间隙型自带冠叶片转子系统设计与优化的有效方法，并面向某型汽轮机进行示范应用。

现代汽轮机转子系统常处于超（超）临界的高柔性状态下运转，与其它类型叶片相比间隙型自带冠叶片与转子之间的振动耦合效应更加突出，油膜力、间隙气流力、密封激振力等非线性因素对系统动力学特性的影响也愈发显著。因此应将叶片、轮盘、转轴和轴承看成一个整体，全面地分析叶片与转子之间的振动耦合效应，从整体上研究系统的动态特性，对于深入自带冠叶片的振动特性，进而提高汽轮机整体的安全性具有重要作用。本项目拟综合利用理论分析、数值计算和试验研究手段，首先基于相似理论，搭建了能够模拟汽轮机实际工况的叶片-转子系统碰撞振动试验台；同时，通过建立自带冠扭转叶片斜碰撞动力学模型，分析叶冠间隙、冠间摩擦系数等不同因素对于叶片振动特性的影响；最后，基于有限元方法，分别建立的叶盘以及叶片-转子系统的动力学模型，进而分析叶盘以及叶片-转子系统在多非线性因素耦合作用下的动力学特性。通过理论分析与仿真计算，本研究提出了基于叶尖定时法的数据预处理算法，提高了叶片振动特性参数的辨识精度；同时，通过所建立叶片碰撞动力学模型，发现冠间摩擦系数对于自带冠叶片振动特性影响不大，叶冠的冠间间隙存在一个最佳区间，以使得叶片振动响应幅值达到最小；通过所建立的叶盘以及叶片-转子系统有限元模型，模拟了不同故障类型下叶盘以及叶片-转子系统的动力学特性，同时利用实验与仿真信号对比结合的方式进行验证，突破了实验缺乏多种故障数据的困难，并且利用监督式自编码器与深度置信网络结合的方式，用于对不同工况环境下不同故障类型的叶片进行分类，解决了叶盘-转子系统故障诊断样本不足的问题，为汽轮机转子系统故障诊断建立基础。通过本课题的研究，更深入的了解了自带冠叶片在多种非线性耦合作用下的动力学特性，同时基于人工智能算法的故障诊断，可有效提高对于自带冠叶片振动异常的监测与故障的诊断。