An optical fiber sensor for simultaneous measurement of flow rate and temperature in the pipeline

An optical fiber sensor was proposed and studied for the simultaneous measurement of flow rate and temperature. It includes a capillary steel tube, an adjustable target and two fiber Bragg gratings (FBGs). The two fiber Bragg gratings were fixed in the tube by glue, and they could be protected well. One end of the tube was assembled in the protective shell, the other end was connected to a target. Flow rate and temperature would both cause the wavelength shifts of FBGs. Without causing a large adjustment, the flow sensitivity of the proposed sensor could be adjusted by only assembling a properly designed target. On the basis of simulation, the proposed sensor was fabricated and realized the simultaneous measurement of flow rate and temperature, which was verified by experiments. Due to the limitation of experiment system, the flow rate accuracy was up to 2.27% in the range of 5-16 m3/h, and the temperature accuracy was under ±1 °C in the range of 23-83 °C. With advantages of compact size, high sensitivity, wide measurement range and small pressure loss, it has a great potential application in many areas.