Research on a novel variable-area optical fiber gas flow sensor

Based on the structure of the traditional variable area flow meter and the principle of the optical fiber measurement, this article designed a new type of fiber Bragg grating (FBG) gas flow sensor. The tapered tube of the sensor is mounted vertically, and the float inside the tube moves up and down under the effect of the airflow. The longitudinal displacement of the float is converted to the deflection of the cantilever which bonded FBG under the action of magnetic force. Thus the flow variation could be transformed into the deflection of the cantilever, resulting in the change of FBG wavelength and phase. By detecting the change of the optical signal, the gas flow can be derived. The experimental results show that the sensor has the characteristics of good linearity and fast response time. The proposed sensor can determine the flow of air within 1-6.5 m3/h and the sensitivity of the sensor approximately reaches 0.22 nm/(m3/h). By optimizing the parameters of the sensor, the sensitivity and the accuracy can be improved accordingly.