基于拉曼散射效应的分布式光纤测温系统研究

发布时间：2018-11-13 11:46

【摘要】：基于拉曼散射效应的分布式光纤测温系统是近年来发展起来的一种新型温度传感系统,此类系统利用单根传感光纤就能够在线测量出沿光纤分布的空间温度场。与以往传统的测温系统相比较,拉曼测温系统具有较高的空间分辨率和温度分辨率;能够实时监测温度,每隔一定时间便会刷新一次温度数据,保证了数据即时有效;此外,系统具有耐腐蚀、抗电磁干扰、防火防爆以及传输距离远等优点,使得它与传统的温度传感器区别开。分布式光纤拉曼测温系统因其本身具有的独特优势,已经广泛应用于航空航天、工业现场、公共安全等领域。本文在回顾光纤传感技术发展背景的基础上,概述了分布式光纤测温系统的国内外研究现状及发展趋势,指出了国产系统存在的不足,确立了本课题的主要研究内容。在分析光纤中的后向散射的基础上,将拉曼散射理论与光时域反射技术相结合,提出了分布式光纤拉曼测温系统的基本原理,通过用Rayleigh光、anti-stokes光以及stokes光分别作为参考光进行计算分析,确定了系统最终选用stokes光作为参考光进行信号解调。根据系统设计要求,本文在计算分析系统所需元器件参数的基础上,对系统元器件进行了选型,搭建了分布式光纤拉曼测温系统。在分析影响系统信噪比因素的基础上,确立了采用累加平均及小波变换相结合的方法来提高系统信噪比;根据信号解调理论,对解调方案的正确性进行了实验验证;研制了温度标定模块,采用对不同温度段温度分别标定的方法,通过对采集到的数据进行分析处理,完成了系统温度标定实验,实现了温度的测量。为了验证分段定标方案的可行性,文章首先对系统空间分辨率、温度分辨率、温度测量精度、响应时间、稳定性及重复性分别进行了测试。测试结果表明:在100℃以内,系统空间分辨率为1m,温度分辨率优于1℃,温度测量精度达±1℃,响应时间为34s,系统稳定可靠、重复性良好;其次,针对油井、核电监测等特殊领域,对高温区域温度的测量进行了探索研究,实现了300℃的测量;最后,对系统主机进行了安装测试,测试结果符合要求,据此完成了一台性能优异且具有一定价格优势的分布式光纤拉曼测温系统样机。
[Abstract]:The distributed optical fiber temperature measurement system based on Raman scattering effect is a new temperature sensing system developed in recent years. This kind of system can on-line measure the spatial temperature field along the fiber by using a single sensing fiber. Compared with the traditional temperature measurement system, Raman temperature measurement system has higher spatial resolution and temperature resolution, can monitor temperature in real time, refresh the temperature data every certain time, and ensure the data to be effective immediately. In addition, the system has the advantages of anti-corrosion, anti-electromagnetic interference, anti-fire and explosion-proof and long transmission distance, which makes it separate from the traditional temperature sensor. Distributed fiber Raman temperature measurement system has been widely used in aerospace, industrial field, public safety and other fields because of its unique advantages. On the basis of reviewing the development background of optical fiber sensing technology, this paper summarizes the research status and development trend of distributed optical fiber temperature measurement system at home and abroad, points out the shortcomings of domestic system, and establishes the main research contents of this subject. Based on the analysis of backscattering in optical fiber, the basic principle of distributed fiber Raman temperature measurement system is proposed by combining Raman scattering theory with optical time domain reflectance technique. By using Rayleigh light, The anti-stokes light and the stokes light are calculated and analyzed, and it is determined that the system uses stokes light as the reference light to demodulate the signal. According to the requirements of the system design, on the basis of calculating and analyzing the parameters of the components required by the system, the system components are selected and the distributed fiber Raman temperature measurement system is built. Based on the analysis of the factors affecting the signal-to-noise ratio of the system, the method of combining cumulative average and wavelet transform is established to improve the signal-to-noise ratio of the system, and the correctness of the demodulation scheme is verified experimentally according to the theory of signal demodulation. The temperature calibration module is developed and the system temperature calibration experiment is completed by analyzing and processing the collected data by using the method of calibrating the temperature of different temperature sections respectively. The temperature measurement is realized. In order to verify the feasibility of the piecewise calibration scheme, the spatial resolution, temperature measurement accuracy, response time, stability and repeatability of the system are tested respectively in this paper. The test results show that: within 100 鈩，

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