基于镀膜光纤布拉格光栅阵列的气体流量传感机理和方法研究

Gas flow sensor is widely used in various areas, such as environment protection, energy monitoring and industrial control. This project, integrated by two disciplines of flow measurement and optical sensing, is proposed for gas flow measurement in the applications of large-diameter and low-velocity, exploring the mechanism and characteristics of gas flow sensor based on coated fiber Bragg grating and founding a precise mathematical model. Through a study of production process of the coated fiber Bragg grating sensor, make out of a sensing element with high accuracy and excellent reliability. Using the sensing element, design a coated fiber Bragg grating array built inside the flow pipe, and create data fusion model and algorithm about the sensing array. Gas flow measurement system based on the coated fiber Bragg grating array is achieved as a result of research on the package materials and package ways of the new gas flow sensor, set-up of optical path of the sensor array and construction of the data acquisition and analysis system. Testing and calibration can be realized while the gas flow measurement experimental calibration system is put up. Furthermore, this project is interdisciplinary and innovative, indicating a importantly scientific and economic value and a broad prospect in the future development.

环保、能源、工业控制领域大量使用气体流量传感器。本课题拟针对大口径、低流速的气体流量测量应用，交叉流量测量与光学传感两个学科，提出基于镀膜光纤布拉格光栅阵列的气体流量测量新方法。研究镀膜光纤布拉格光栅流量传感机理及特性，建立精确数学模型。研究镀膜光纤布拉格光栅传感元件的制作工艺，研制准确度高、可靠性强的传感元件。研究设计内置于测量管段中的镀膜光纤布拉格光栅阵列，建立阵列传感数据融合模型与算法。研究新型气体流量传感元件封装材料及封装方式，构建传感阵列光路及数据采集分析系统，研制基于镀膜光纤布拉格光栅阵列的气体流量测量系统。在现有装置基础上搭建气体流量测量实验标定系统，进行测试和标定研究。本项目属于交叉学科研究，创新性强，具有重要的研究价值和广阔的应用前景。

本项目旨在围绕光纤热式流量传感技术提出一种新型镀膜光纤布拉格光栅流量传感器及其传感阵列，系统地研究了镀膜光纤布拉格光栅热式流量传感技术、阵列传感技术及管道流量测量技术。研究并提出了自由及管道空间内的镀膜光纤光栅流量传感数学模型。基于数学模型，采用Fluent软件仿真分析了管道内镀膜光纤光栅流量传感器的温度场分布、速度场分布及封装口径对传感元件的影响。建立了一套用于刻写4 mm光纤光栅的刻写系统，采用真空蒸镀工艺对光栅侧表面进行镀膜加工，厚度约为120 nm。设计并制作了三种耦合方法的镀膜光纤光栅流量传感器，分别是错位熔接、多模光纤熔接及腰椎增大熔接。研究结果表明，错位熔接传感器分辨率为0.022 m/s，多模光纤熔接传感器为0.031 m/s，腰椎增大熔接传感器为0.028 m/s，其中，多模光纤熔接方式制作重复性较好，且泵浦功率较高时不易出现光栅啁啾效应，减少了测量误差。为了实现大口径、低流速管道应用，设计并搭建了50 mm口径、0-10 m/s流速的气体管道流量标定及测量装置。在此基础上，研究了传感阵列测量的实现方式，并结合速度面积法实现了管道气体流量的精确测量，误差在±1.5%以内。该项目的研究既拓展了新型光纤传感器的研究领域—光纤有源传感器，又为光纤流量传感器在管道中应用提供了新方法、新方案以及模型和数据支持，具有重要的科学指导意义。