基于周向激励的磁性管道泄漏检测技术

Magnetic Pipeline Leak Detection TechnologyBased on Circumferential ExcitationAbstractThe issue is in close connection with actual scene,solves the quantitative andintelligent problems,through theoretical analysis,modeling and simulation to experiments,thesis systematically summed up the technology of long-distance pipelines magnetic fluxleakage under circumferential excitation.The paper deeply studies on theory,relationshipbetween the pipeline defect characteristics and magnetic flux leakage signals,influencingfactors,magnetic circuit design of the system,and practical application.Basing on the theory of finite element analysis,the paper uses ANSYS to simulate theflaw leakage magnetic field of long-distance pipeline under circumferential excitation,realizing the magnetic field simulation about oil pipeline leakage defects,researches therelations between signals and the feature of flaw,the geometrical and material parametersof magnetized section,the lift-off height of sensors and the thickness of pipelines,differentiate four typical defects through the wing chart analysis.Thesis puts forward thegeneral principle of magnetic circuit calculation,based upon the two basic magneticequations and Cauchy equation,models and deduces the magnetic circuit calculationformula of the devices,and then designs the circumferential excitation magnetic fluxleakage inspection devices.Apply MATLAB to program the GUI magnetic circuit design,which achieves interaction conveniently,shortens developing cycle of the equipments.Forthe magnetic design of the circumferential excitation device is complex,the paper analysesthe pipelines saturation,puts forward the general requirements including the stability anddetestability,and validates it through 325 pipelines comparison.Use hall element astesting sensors and data acquisition card UA301 to do the actual measurement,experimental results verify the detecting magnetic flux leakage signals of concave defectunder circumferential excitation is correct.The subject achieves correct magnetic circuit design of the circumferential excitationmagnetic flux leakage inspection devices,solving the domestic problem that magnetic fluxleakage inspection devices can not detect the axial distribution pipeline defects,usingⅡ