Condition Monitoring Of Liquid Cylindrical Shell Structure Based On Optical Fiber Sensing Technology

Nondestructive monitoring and identification technology has always been a focus of attention.Fiber optic monitoring technology is a new method developed in recent years,the fiber Bragg grating sensing technology has been mature in engineering practice,and has been applied in the field of civil engineering,aerospace engineering.Compared with the fiber grating sensing technology,the distributed optical fiber sensing technology with back Rayleigh scattering has greater convenience and advantages.With the continuous development of distributed optical fiber technology,this technology has been highly valued for its unique advantages.In this context,a distributed optical fiber sensing technique is used to monitor the liquid level and inclination Angle of cylindrical shells.The main research results include: analyzing the principle and technical characteristics of distributed optical fiber sensing,and putting forward a scheme of optical fiber distribution design and information acquisition.Make full use of the advantages of distributed optical fiber sensing technology,including the sensitivity to strain,the continuity and precision along the optical fiber signal,and design the optical fiber layout and direction.The strain information of the key parts of the structure of liquid cylindrical shell is recorded and collected,so as to provide the basis and basic information for the identification,monitoring and detection of the internal liquid situation,environment and state of the cylindrical shell container.A method for calculating liquid level and inclination Angle based on cyclic strain information is proposed.The relationship between the circular strain and the hydrostatic pressure produced by the liquid is studied by numerical simulation.Numerical simulation and experimental results show that the circumferential strain and internal hydrostatic pressure are linearly related along the axis of the cylindrical shell.This relationship requires two or more ring-to-fiber laying near the liquid level.According to the characteristics of strain distribution and the information collected by distributed optical fiber sensors,the location of liquid surface can be determined accurately.The numerical simulation and experimental results show that more than two axial optical fibers can be used to determine the inclination of liquid surface and horizontal surface.Thus,a method is developed to evaluate the position and inclination Angle of liquid-containing cylinder shell,and the best testing range of this method is given.An experimental method is used to verify the method of distributed optical fiber sensing for testing liquid-containing cylindrical shells.A whole set of experimental schemes are designed,including fiber sensor path,calibration experiment,fiber sensor package and data acquisition and processing.The results show that the liquid level and inclination Angle can be obtained accurately by using the distributed optical fiber sensing technology and the strain information of special position.It also shows that this method has a good application prospect.