A Non-Invasive Measurement Method of Pipeline Flow Rate Based on Dual FBG Sensors

Combining fiber Bragg grating (FBG) sensors and finite element simulation analysis, an online monitoring method for non-invasive distributed flow velocity in pipelines has been proposed. A placement strategy has been proposed for the deployment of these FBG sensors to ensure effective sensing of strain. The cross-sensitivity problem of FBG sensors can be solved by differential FBG measurements. The principle of online monitoring of flow velocity based on the flow velocity function and finite element analysis is described and derived. Finite element analysis results show the
$\boldsymbol {\varepsilon }_{1}- \boldsymbol {\varepsilon }_{2}$
at 45° of the elbow of the bend is quadratically proportional to the flow velocity. Meanwhile, the feasibility of the method is verified by experiments. The calibration results show a fitted correlation coefficient R
²
= 0.9982 in the velocity range of 4.25-10.62m/s, fitted by least squares to the wavelength data. The repeatability error of the flow measurement of the proposed sensor is no more than 5.06%FS. Compared with the existing literature, the method proposed in this paper has a wider range of flow velocity measurement and applications, especially suitable for applications with strong electromagnetic interference capability and harsher environment, showing great potential for engineering applications, especially in the distributed detection of long-distance pipeline networks.