基于双光纤布拉格光栅的流速传感器

Flow Velocity Sensor Based on Double Fiber Bragg Gratings

设计了一种基于双光纤布拉格光栅的新型流速传感器,它包括双光纤光栅压强传感机构和文丘里管。导出了双光纤布拉格光栅的波长漂移差与流速的关系。压强传感机构中的密闭铝箔管横截面两边的压力差导致等腰三角形悬臂梁变形,从而导致安装在悬臂梁两边的光纤布拉格光栅的布拉格波长漂移。通过检测两个布拉格光栅的波长漂移差,得到被测流体的流速。双光纤布拉格光栅通过补偿温度效应,解决了光纤布拉格光栅传感器的交叉敏感问题。该流速传感器的动态测量范围为8～200mm/s。实验表明,双光纤布拉格光栅的中心波长随流速的增加分别向长波和短波方向漂移,而带宽几乎不变,实验和理论符合得较好,该设计方案是切实可行的。

By using the fiber grating pressure sensing setup and Venturi tube, a novel flow velocity sensor based on double fiber Bragg gratings （FBGs） is proposed. The relationship between the flow velocity and the wavelength shift difference is derived. The pressure difference of the two sides of the cross section of the aluminum foil tube in the pressure sensing setup results in the distortion of an isosceles triangle cantilever structure. And the distortion results in the Bragg wavelength shift of the FBGs mounted at either side of the cantilever. By monitoring the wavelength shift difference of the two FBGs, the flow velocity can be obtained. The cross sensitive problem can be solved by compensating the temperature effect. Experimental results are in good agreement with theoretical analysis. The central wavelength of two FBGs shifts to the shorter and longer wavelength respectively with the rise of the flow velocity, while the bandwidth is almost unchanged. The experimental results verify the feasibility of the proposed sensor with a measurement range of 8-200 mm/s.