Research Of Fiber Optic Interferometor For Fluidic Velocity In Circular Pipe

With the rapid development of fiber optic sensors in various fields,the measurement methods of fluid flow velocity in different types of pipes are also constantly changing.This paper studies the measurement of fluid flow velocity in a miniature circular pipe.1.Basic principle of the interference fiber optic sensor is analyzed and several typical applications of the interference fiber optic flow velocity sensor are listed,which provides a theoretical basis for the proposed interference fiber optic flow velocity sensor.2.A flow velocity measurement sensor based on the Fabry-Perot(FP)interference principle is proposed and designed.The single-mode fiber(SMF)end face and polymer film are used as the two reflecting mirror of the FP cavity.The sensor is inserted into the pipe from the radial and axial directions of the round pipe to sense and measure the flow velocity.Combined with Bernoulli's theorem,the flow velocity is finally measured by analyzing its reflection spectrum.Compared with the optical fiber sensors that use traditional water film,silver film,silicon film and other thin films as reflection mirrors to measure the flow rate,the polymer films(PVC and PC)selected in this experiment are not only easy to obtain,but also have low elastic modulus,Good optical characteristics and other advantages,so the manufacturing cost is greatly reduced,and the sensitivity of the sensor to measure the change in flow velocity is also improved,and at the same time,a larger output light intensity can also be obtained.The measurement experiment results have proved that the FP sensor has achieved high sensitivity and linearity by measuring the flow velocity of in the round pipe in two directions.3.A target-based flow velocity sensor is designed based on the FP interference principle.The polymer film and the end surface of the SMF are also used as the two reflecting mirror of the FP cavity,and in this chapter,a plastic elastic material is selected to sense and measure the change of the flow velocity.The sensor was used to measure the flow velocity of the fluid in the round pipe.By analyzing the change of its reflection spectrum,a higher sensitivity of flow velocity measurement is achieved.By analyzing the change of its reflection spectrum,a high flow velocity measurement sensitivity is achieved.At the same time,we compare and summarize the measurement results of this sensor with the flow velocity sensor based on the dynamic pressure of the round pipe.Compared with the traditional flow velocity measurement sensor,the target-type flow velocity sensor designed in this experiment is not only easy to implement,but also has the advantages of non-contact,high sensitivity and low cost.It can provide a certain reference for the measurement and research of the fludic velocity in the micro pipe...