YE De-chao, DUAN Fa-jie, ZHOU Qi, CHENG Zhong-hai, LI Xu, NIU Guang-yue
（State Key Lab of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China）
Abstract：With the development of power plants towards high power and intelligent operation direction, the vibrations or failures of blades, especially the last stage blades in steam turbines, happen more frequently due to the unstable operating conditions brought by flexible operation. A vibration measuring method for the shrouded blades of a steam turbine based on eddy current sensors with high frequency response is proposed, meeting the requirements of non-contact heath monitoring. The eddy current sensors produce the signals which are related to the area changing of every blade’s shroud resulting from the rotation of stator. Then an improved blade tip timing (BTT) technique is proposed to detect the vibrations of shrouded blades by measuring the arrival time of each area changing signal. A structure of eddy current sensors is developed in steam turbines and an amplitude modulation/demodulation circuit is designed to improve the response bandwidth up to 250 kHz. Vibration tests for the last stage blades of a steam turbine were carried out and the results validate the efficiency of the improved BTT technique and the high frequency response of the eddy current sensors presented.
Key words：steam turbine; blade vibration measurement; eddy current sensor; blade tip timing
CLD number：TP272.2 Document code：A
Article ID：1674-8042（2019）04-0315-07 doi：10.3969/j.issn.1674-8042.2019.04.002
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基于高频响电涡流传感器的汽轮机带冠叶片振动测量技术
叶德超， 段发阶， 周 琦， 程仲海， 李 旭, 牛广越
（ 天津大学 精密测试技术及仪器国家重点实验室， 天津 300072）
摘 要: 针对汽轮机带冠叶片的健康监测需求， 提出了一种基于高频响电涡流传感器的带冠叶片振动参数测量方法。 转子旋转时， 电涡流传感器感知叶冠面积变化， 通过检测叶片发生振动时叶冠面积变化信号的到达时间， 并应用叶尖定时（Blade tip timging, BTT）数据分析方法获取叶片振动参数。 设计了一种适用于汽轮机工作环境的电涡流传感器和一种高带宽调幅解调电路， 使响应带宽达到250 kHz以上。 某型汽轮机末级叶片振动试验结果表明所设计的高频响电涡流传感器和变面积型叶尖定时测振技术在汽轮机带冠叶片的应用是可行的。
关键词: 汽轮机； 叶片振动； 电涡流传感器； 叶尖定时
引用格式： YE De-chao, DUAN Fa-jie, ZHOU Qi, et al. Vibrations measurements for shrouded blades of steam turbines based on eddy current sensors with high frequency response. Journal of Measurement Science and Instrumentation, 2019, 10（4）： 315-321. ［doi： 10.3969／j.issn.1674-8042.2019.04.002］
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