基于无源光纤法珀传感系统的航空发动机涡轮叶片高温应变监测关键技术研究

Dynamic strain measurement added on the very large static strain in high temperature are often needed for turbine blades of aircraft engine. While there is no effective method to monitor these parameters. To solve this problem, Sapphire fiber and alumina micro-tube are used to fabricate Fabry-Perot sensor based on piston type; Blackbody cavity fabricated on one end face of sapphire fiber is used as input light source of Fabry-Perot sensor; Dynamic demodulation method for strain based on Fizeau interferometer are analyzed, influence of bandwidth and intensity of blackbody source for demodulation are also investigated. Blackbody radiation is also used to measure temperature to compensate the strain of turbine blades in high temperature..This research is possible to make breakthrough for new fiber optical sensors design and demodulation methods for fiber optical sensors; especially for improving demodulation method’s measurement accuracy and speed. It is also helpful to improve design level and safety of aircraft engine. This research results can be applied in other monitoring environments which require strain measurements in high temperature.

针对航空发动机涡轮叶片在高温下的极大静应变与频率极高动应变的监测需求，从光纤法珀传感器结构出发，分析传感器结构对应变测量范围的影响，设计基于蓝宝石光纤和氧化铝微管的活塞式光纤法珀传感器；将传感器远端蓝宝石尾纤制作成黑体腔，利用高温下黑体辐射能作为光纤法珀传感器的输入光源，根据非扫描式相关解调原理，研究基于光学互相关模块（斐索干涉仪）的无源光纤法珀传感器高速解调方法和系统；同时，利用黑体辐射强度与温度之间的关系测量温度，实现对高温应变的温度补偿。.本项目的研究极有可能在光纤传感器设计和解调技术上取得新突破，在保持极小传感器体积前提下、提高光纤法珀传感器的环境适应性、测量精度和测量速度；形成满足航空发动机涡轮叶片高温应变监测要求的新测量技术，进而有助于提高我国航空发动机的设计水平和安全系数。本项目成果还可以用于其他极端工作环境下的高温应变测试，极大地拓展光纤法珀传感系统的应用范围。

针对航空发动机涡轮叶片的高温应变监测需求，从黑体光源发射腔的设计与实现、黑体光源与光纤的耦合效率研究、基于黑体光源的高温应变测量与温度补偿原理，活塞式法珀传感器的设计，基于光学互相关扫描的高速解调原理与系统实现，基于黑体光源的光纤法珀传感器高温应变验证实验等方面开展了深入研究。研究结果表明，在高温环境下黑体辐射可作为光纤法珀传感系统的光源；同时利用黑体辐射中心波长与温度之间关系，可实现高温应变的温度补偿。基于光学互相关扫描原理设计的解调系统可实现5kHz高速解调。活塞式法珀应变传感器可在1000°C内实现高温应变测量。本项目研究在光纤传感器设计与解调系统上取得了一定突破，在保持极小传感器体积前提下、提高光纤法珀传感器的环境适应性、测量精度和测量速度；为航空发动机涡轮叶片高温应变监测引入光纤传感新测量技术奠定了重要理论与技术基础。本项目成果还可以用于其他极端工作环境下的高温应变测试，极大地拓展光纤法珀传感系统的应用范围。