Research On Key Technologies For Optical Fiber Health Monitoring Of Flexible Energy Transmission Pipelines

With the deepening of modernization,energy has become an essential material basis in human production and life.As an efficient and convenient transportation mode,pipeline has been widely used,and flexible pipeline has become the first choice for oil and gas transportation with its unique advantages.However,the complex environment and harsh conditions often make the flexible pipeline invalid due to deformation,leakage and other reasons,leading to a series of social and ecological problems.In view of the limitations of traditional detection methods and the urgent need for health assessment of flexible pipeline in long-distance transmission,it is urgent to study practical flexible pipeline detection methods.The emergence of optical fiber sensing technology provides a new solution for pipeline health monitoring.Therefore,the research on the key technology of flexible pipeline optical fiber health monitoring is of great significance.This dissertation aims to study the optical fiber sensing technology in the health monitoring of flexible pipeline,and aiming at the failure faults such as large bending strain and leakage that may occur in the service process of flexible pipeline,firstly,an integrated packaging solution of optical fiber sensor and flexible pipeline is proposed,which provides the possibility for the application of optical fiber sensing technology in flexible pipeline.Then,the principle and composition of weak fiber Bragg grating sensing technology are studied,and a curve reconstruction algorithm based on arc model is proposed.Combined with fiber shape sensing technology,the shape visualization of flexible pipeline under large bending strain is realized by MATLAB.In addition,this dissertation studies the basic principle and composition of distributed fiber acoustic sensing technology and distributed fiber temperature sensing technology.Two kinds of optical fiber sensing systems are constructed to sense the vibration and temperature changes around the pipeline and detect the possible leakage accidents of flexible pipeline.The heat transfer model of flexible pipeline is constructed by using COMSOL finite element software,and the heat transfer process of fluid and solid coupling in flexible pipeline under multiple physical fields is studied.Finally,this dissertation establishes a typical optical fiber health detection method with multiple physical quantities such as strain,vibration and temperature,which provides basic means and technical support for the formation of "intelligent flexible pipeline".