Research On Oil Level Monitoring System Based On Optical Fiber Sensor

Optical fiber sensors have the advantages of high sensitivity and strong antiinterference ability,and are widely used in defense,military,petrochemical,aerospace and other fields.Fiber grating sensors have good sensitivity to strain and temperature,so they have become one of the hot spots in the research and application of fiber optic sensors.At the same time,due to the characteristics of intrinsic passive,anti-electromagnetic interference,and can be used in extreme environments,optical fiber sensors have attracted widespread attention in recent years for their liquid level measurement applications in special environments.In this thesis,based on the application requirements of oil tank liquid level monitoring,the research of oil level monitoring system based on optical fiber sensor is carried out.The main work contents are as follows:(1)Using the pressure sensitive principle of fiber grating,the development of fiber optic liquid level sensor based on the principle of pressure measurement was carried out.The thesis uses pressure-sensitive diaphragm to sensitize the fiber grating,and develops a pressure sensor device combining pressure-sensitive film and fiber grating.The influence of the thickness of the pressure-sensitive film on the performance of the fiber grating pressure sensor and the accuracy of oil level monitoring are studied.Theoretical analysis and experimental research show that: the thinner the pressure-sensitive film,the higher the sensitivity of the fiber grating pressure sensor.The maximum relative error of the fiber grating pressure sensor developed by the thesis for liquid level measurement is 4.956%.(2)The thesis carried out the experimental research of the oil level monitoring system of fiber grating pressure array sensor.An improved FBG pressure array sensor oil level monitoring algorithm is introduced to improve the monitoring accuracy of the FBG pressure array sensor.In addition,the development of the application software of the fiber Bragg grating oil level monitoring system was completed,the oil level monitoring system of the fiber grating pressure array sensor was built,and the oil level monitoring experiment of the fiber grating pressure array sensor was conducted.The experimental results show that the maximum relative error of the liquid level measurement of the fiber grating pressure array sensor based on the improved algorithm is 4.059%,and the system has the advantage of not being affected by the liquid density,acceleration of gravity,and ambient temperature.(3)The thesis also carried out the research of oil level monitoring system based on fiber grating temperature sensor.The composite sensing structure of carbon fiber heating rod and densely distributed temperature measurement fiber grating array was designed.Using the temperature sensitive principle of fiber grating,the carbon fiber heating rod was periodically heated by the heating pulse controller to develop a liquid based on the principle of fiber grating temperature measurement Bit sensor.By building an experimental system,a liquid-fiber temperature sensor liquid level measurement experiment was carried out.The experimental results show that the optical fiber grating temperature sensor oil level monitoring system can effectively obtain the grating position where the liquid level is located.The accuracy of the liquid level measurement achieved in this paper is ± 1cm.