Research On Dynamic Characteristics And Vibration Optimization Of The PIG

Pipeline is one of the main ways to transport oil and gas resources across regions,and pressure-driven Pipeline Inspection Gauge(PIG)is an important equipment to ensure the timely commissioning and safe operation of pipelines.There are internal features and defects such as girth welds,elbows and dents in the pipeline,and the PIG,as a complex mechanical equipment,will exhibit complex nonlinear dynamic behavior when colliding with the above features,which will seriously affect the safe and stable operation of the PIG.In this paper,firstly,by analyzing the mechanical characteristics of the sealing disk and PIG,the discrete dynamics model of the sealing disc and the overall dynamics model of the single-section PIG and the overall dynamics model of the multi-section PIG connected by double universal joints are established,and the vibration equations of the single-section PIG are derived when it is subjected to radial excitation in the tube and when it passes through the elbow.The Adams model of the PIG was established by deriving the one-dimensional fluid equations in the tube and writing its numerical calculation program,and combined with the Adams dynamics simulation software to realize the joint simulation of Simulink and Adams for fluid-structure coupling.The joint fluid-structure coupling simulation was carried out for single-section and multi-section tandem PIGs passing through ring welds,depressions and elbows,respectively,and the time domain and frequency domain analyses of the PIG vibration characteristics when the pipe characteristics and PIG operating parameters change were carried out.It is found that the PIG will produce great vibration response after being excited by depressions,ring welds and elbows,and the acceleration of its center of mass in different directions has obvious tendency to change with the operating and structural parameters,and the multi-section tandem PIG can transfer the action of axial force through the duplex universal joint,and the forced vibration state of each section at the same moment varies greatly.To address the problem of excessive vibration of the PIG,a neural network was further utilized to map and find the optimal vibration strength results corresponding to the orthogonal test simulation data of multiple parameters,and three sets of PIG design and operation parameters corresponding to the smallest vibration strength were obtained.It is found that when the equivalent stiffness of the sealing disk is reduced,the position of the center of mass of the PIG is changed,and the PIG is operated in a reasonable speed range,the vibration response of the PIG generated by the in-tube excitation will be weakened.