Optical fiber FBG linear sensing systems for the on-line monitoring of airborne high temperature air duct leakage

Electrical sensing systems, such as those involving eutectic salt, are mostly used in connection to leakage from existing airborne high-temperature air-conducting pipelines. Such complex structured systems are susceptible to external interferences and, thus, cannot meet the increasingly strict monitoring needs of a complex air-conducting pipeline system of an aircraft. In view of this point, this paper studies an alternative sensor system based on a dense array fiber grating. To obtain a compact and light-weight airborne signal processing system, a field programmable gate array is used as the main control core that controls the output of the light source. The functions of pulse modulation, analog-to-digital conversion, data buffering and transmission are integrated into a single system, while the linear sensing monitoring is obtained by detecting the time-division and wavelength-division wavelength drift signals of the fiber Bragg grating array. Our experiments show that the spatial resolution of the linear sensing system approaches 5 cm, the temperature measurement accuracy reaches 2 ℃, the temperature measurement range is between 0-250 ℃, and the response time is within 4 s. Compared with the existing electrical monitoring systems, various monitoring indicators have been greatly improved and have broad application prospects.     

用于轴瓦温度监测的无线耦合光纤布拉格光栅传感器

十字头轴瓦的磨损是压缩机无法正常使用的重要原因之一,实时检测轴瓦处的温度进而来判断轴瓦的磨损情况是确保压缩机安全、高效生产的重要检测手段。针对石化行业复杂的工况环境,提出并设计制备了一种无线耦合光纤布拉格光栅传感器,并用其进行光信号的空间传输以实现轴瓦处温度信号的提取。针对动态测量过程中产生的U型中心波长信号引起的解调温度差值过大的问题,利用插入损耗阈值,将一次动态运行过程中的温度改变量从4℃控制到0.1℃以内,提高了温度解调的准确度,实现了温度的无线监测。