Study On Fiber Bragg Grating Based Flow Sensor

As a kind of wavelength demodulated fiber optic sensors, fiber Bragg grating sensor has many advantages such as simple structure, small size, strong anti-interference ability, little long-term drift and high accuracy. In the past decades, it has been widely used in the industrial measurements, large-scale structural health monitoring, smart materials and other fields. Flow measurement is one of the most important parameters which can be detected by fiber optic sensors in harsh industrial environments with high temperature, high pressure and strong electromagnetic interference.In this thesis, we review the progressing of fiber Bragg grating devices, its sensing applications, and analyze the current status of commercial flow measurement technology and optical flow sensor; according to the principle of writing the fiber Bragg grating, fiber Bragg gratings were fabricated in the laboratory using the mask of1550nm and1558nm; we designed a new type of flow sensor based on two fiber Bragg gratings and the cantilever beam which can compensate the frustration of environment temperature and pressure changes as well as the interior changes such as the light source fluctuations; based on the relationship between the central wavelength drift and the flow rate, the simulated results based on MATLAB were presented. We fabricate and test the designed fiber Bragg grating flow sensor system, the testing results clearly show that the fiber Bragg grating flow sensor achieve a resolution as0.59%during a measurement range0-1000liter per hour in a30mm-inner flow loop, and the stability is2.16%; on the basis of the dual fiber Bragg grating flow sensors, we also make preliminary analysis of three-dimensional flow sensor and verify its feasibility for flow measurement with direction detection. By the end of this thesis, the problems of fiber Bragg grating flow sensor system and some possible optimizations about current system are provided for further investigation.