Optical Fiber Flow Sensor Based On Interference Principle

With the development of information technology,sensing technology based on optical fiber devices has emerged.The reason why fiber optic sensors can be widely used in many fields is inseparable from the advantages of fiber optic sensors.Compared with the traditional electronic sensor,it can measure the parameters in some remote mountainous areas,and many physical parameters can be measured simultaneously.Flow rate,as an important parameter in oil field transmission pipeline,river and hydroelectric power station,requires high precision of sensor.At present,how to measure the fluid flow safely and efficiently is a research hotspot in the sensing field.In this paper,two kinds of interferometer sensors are designed for fluid flow measurement,and their sensing performance is discussed.The main research contents include the following parts:Firstly,this paper introduced the types of interferometric optical fiber sensors and the working principle of each type of sensor,with emphasis on the working principle and advantages and disadvantages of the flow measurement method based on optical fiber devices.Secondly,an optical fiber micro-flow rate sensor based on Michelson interferometer is proposed.The components and working principle of the sensor are introduced.The sensor's sensing principle is studied through theoretical derivation.Emphasis is placed on the simulation of sensor parameters using numerical simulation methods.From the results,it is concluded that the sensor sensitivity can be improved by the smaller dual-core fiber length,small ball radius and fluid density,and the sensor sensitivity is not significantly affected by the change of fiber core spacing.The sensor can also be used to measure high sensitivity when parameters change slightly.At the same time,the relation between the free spectrum range of the output spectrum of the sensor and the different parameters of the sensor is deduced and calculated,and the relation between the free spectrum range and each parameter being 1/x or 1/x1.5 is obtained.Third,a new pipeline flow measurement method based on Mach-zehnder interferometer is proposed.Through theoretical derivation and analysis of the working principle and sensing method of the flowmeter,the numerical simulation method is mainly used to simulate the parameters of the flowmeter.It can be concluded from the results that the smaller pipe wall thickness and the length of the dual-core fiber can improve the sensitivity of the flowmeter,and the sensitivity of the flowmeter can be improved by appropriately increasing the inner radius of the pipe and the angle between the two ends of the dual-core fiber and the center of the circle.The flowmeter has high sensitivity and simple operation,reduces the error caused by intrusion into the fluid and measures the flow rate,and is an ideal method for measuring the flow rate of the flow pipeline.