环境激励下的旋转机械工作模态参数辨识

伴随着高速透平机械向大跨度、柔性结构方向发展，转子-轴承系统的稳定性将面临着严峻考验。在出厂测试阶段，确保机组转子系统具有足够稳定性裕度是降低生产现场机组发生失稳故障风险的重要手段。采用适用于随机平稳环境激励下的随机子空间法，对机组的模态参数进行辨识，可规避在转子非驱动端增设电磁激振器的传统测试方法。通过分析转子振型进动方向，区分一阶正反进动的模态参数。结合3-σ统计聚类算法，剔除非稳定的噪声或物理极点，形成了区分转子系统的正反进动的稳态图。数值仿真表明，随机子空间法可以有效地辨识系统的模态参数，利用旋转机械的振型进动方向分析方法可以区分正反进动。此外，通过传统扫频激励模态参数辨识试验，验证了随机子空间方法的辨识精度和工程测试可行性。研究结果可为透平机组的稳定性测试提供技术和理论支撑。

Operational Modal Identification for Rotating Machinery under Environment Excitation

With the development of high-speed turbo machinery with the large span and flexible structure, the rotordynamic stability of the rotor-bearing system faces server challenges. The shop test to ensure the unit with an enough rotordynamic stability margin is an important process to reduce the risk of the instability fault of field units. Using the stochastic subspace identification (SSI) method, which is suitable for the random stationary environment excitations, to identify the modal parameters of units can avoid the traditional method that needs an additional electromagnetic exciter installed at the none-drive end of the rotor. The first forward and backward modal parameters are distinguished by analyzing the whirl directions of modal shapes. The unstable noise and physical poles are eliminated by combining the 3-σ clustering algorithm, and the stabilization diagram that can distinguish the forward and backward whirl modes of rotor system is also obtained. The numerical simulation results indicate that the SSI method can effectively identify the system modal parameters, and forward and backward whirl modes can be distinguished with the whirl direction analysis method of modal shapes in rotating machinery. Moreover, the traditional modal parameters identification method with sine-swept excitations is used to experimentally validate the identification accuracy of SSI method and its feasibility for industrial tests. The study result can provide technical and theoretical support for the stability test for turbo machinery units.