Abstract It is of great importance to accurately evaluate the stability margin of a turbomachine both in shop tests and in operation. The damping ratio of the first forward whirl mode is the key indicator of rotordynamic stability. In this paper, a fast operational modal analysis (OMA) technique based on the singular value of the directional power spectra density function (dPSDF) matrix was developed to estimate the damping ratios of the first forward and backward whirl modes. Numerical simulations and experiments were carried out to verify the accuracy of this method on a high-speed test rig. Moreover, the dPSDF-based method was compared to two conventional OMA methods - data-driven and covariance-driven stochastic subspace identification (SSI) methods - resulting in more stable and accurate estimates for the damping ratio along with a much faster identification time (less than 0.5 s). This study provides an accurate and fast method for performing stability shop tests for turbo machines and stability online monitoring.

中文翻译：

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基于方向功率谱密度函数矩阵奇异值的旋转机械阻尼比快速辨识方法

摘要 在车间试验和运行中准确评估涡轮机的稳定性裕度具有重要意义。第一前向涡流模式的阻尼比是转子动力稳定性的关键指标。在本文中，开发了一种基于方向功率谱密度函数 (dPSDF) 矩阵奇异值的快速操作模态分析 (OMA) 技术来估计第一向前和向后涡流模式的阻尼比。进行了数值模拟和实验，以验证该方法在高速试验台上的准确性。而且，基于 dPSDF 的方法与两种传统的 OMA 方法——数据驱动和协方差驱动的随机子空间识别 (SSI) 方法进行了比较——导致对阻尼比的更稳定和准确的估计以及更快的识别时间（小于 0.5 s)。本研究为涡轮机稳定性车间测试和稳定性在线监测提供了一种准确、快速的方法。