Research On Flow Sensor Based On Fiber Bragg Grating

Flow measurement is an important part of modern test and measurement technology.Flow sensors are widely used in various fields of industrial production and life.Traditional flow sensors generally have shortcomings such as large size,complex structure,poor accuracy and susceptibility to electromagnetic interference.A new type of fiber grating flow sensor made by combining fiber gratings with traditional flow sensors and using optical signals instead of electrical signals can be used,which overcomes the shortcomings of traditional flow sensors to a large extent.Therefore,flow sensors based on fiber gratings have been paid more and more attention by scientific researchers.Based on the traditional flow sensor,combined with fiber grating sensing technology,this paper conducts fiber grating-based flow sensing research.The main content includes sensor production design,simulation,and sensing test experiments.The general content is as follows:(1)The finite element method is used to simulate the orifice flow sensor,the balance flow sensor and the thermal flow sensor to compare the pressure loss of the three kinds of flow sensors.The number of functional holes and the thickness parameters of the porous plate are simulated.After the number of functional holes is simulated,the number of functional holes with the least pressure loss and the best rectifying effect is determined to be 12.In the simulation of the thickness of porous plate,the time of simulation is greatly reduced by using parameterized setting,and the optimal thickness is determined to be 4 mm.Finally,two differential pressure detection systems based on fiber Bragg grating are designed and their structures and working modes are introduced in detail.(2)Deduced the principle of FBG thermal gas flow sensor,designed a fiber grating thermal flow sensor that can be used for gas,and performed temperature and flow sensing test experiments on it,which conform to the FBG temperature sensing principle and the flow sensing principle of thermal flow sensor.After experimental testing,the average temperature sensitivity of the FBG gas flow sensor is 13.24 pm/?,and the flow response curve fit is 0.99712,the measurement range of gas flow can reach 10.203 Nm~3/h.Finally,through simulation,the pressure loss of the designed FBG thermal gas flow sensor is only 3.12 Pa.(3)A liquid thermal flow sensor that can be used for low flow is designed,which expands the application field of FBG thermal flow sensor.The thermal conductive glue filled in the sensor has good thermal conductivity,which helps the sensor to exchange heat with the outside world.The temperature and flow sensing test experiments are done on the sensor respectively,which conform to the FBG temperature sensing principle and the flow sensing principle of the thermal flow sensor.According to the experimental data,the average temperature sensitivity is11.73 pm/?.When discussing the range,considering that the sensor is used in low-flow liquids,there will be a dead zone problem when the flow is near 0,so the sensor range is set to40.575?550.664 L/h.In addition,the micro ceramic heating sheet with suitable heating power can be selected according to the actual situation to increase the range of the sensor,so that the sensor achieves the optimal range and measurement effect.Finally,through simulation,the pressure loss of the designed low-flow FBG thermal liquid flow sensor is only 22.24 Pa.