转子涡动对涡轮叶片非接触式应力测量精度的影响研究

利用叶尖计时（BTT）技术进行涡轮叶片健康监测时,为了获得叶片的真实应力状态和保证测量的高精度要求,本文考虑了转子涡动对叶片非接触式应力测量（NSMS）精度的影响。首先推导了考虑转子涡动的叶片振动提取算法;并通过建立叶片振动有限元模型,模拟了转子不平衡作用下叶片-转子系统的动力学性能。通过对比考虑涡动和不考虑涡动两种算法提取的叶片振动,得到：不考虑转子涡动时,叶尖振动位移幅值为10μm,速度幅值为1.5 m/s考虑涡动时,叶尖振动位移幅值为6μm,速度幅值为1 m/s。结果表明：不考虑转子涡动时,得到的叶尖振动将会偏大,进而使得计算应力大于实际值,不能表达叶片运转过程中的真实应力状态。本文的研究可为提高涡轮叶片NSMS精度提供依据。

The effect of a rotor whirl orbit on the accuracy of non-intrusive stress measurements for a turbo fan

This paper considers the effect of rotor whirl on the accuracy of non-intrusive stress measurements (NSMS) in turbine blade health monitoring,in order to acquire the actual blade stress and ensure the high precision of the measurements. We first deduced the blade vibration algorithm by considering the effect of rotor whirl on the expected arrival time. Then, the dynamic characteristics of a blade-rotor system with rotor imbalance were simulated by establishing a 3D finite element model. Based on the proposed algorithm, the blade vibration was acquired and was compared with that in the absence of whirl. When considering the whirl, the vibration displacement amplitude is 10μm and the velocity amplitude is 1.5 m/s, while without considering the whirl, the vibration displacement and velocity amplitudes are 6μm and 1 m/s respectively. The results demonstrate that without considering the effect of rotor whirl, the blade vibration displacement and stress were more than the true value, and thus cannot reflect the dynamic stress state of the blade during rotation. This work provides a significant foundation for improving the accuracy of NSMS.