Nonlinear Dynamic Analysis Of Pipeline-Regulating Valve System Based On Transfer Matrix Method

Due to the complexity of the control system structure,fluid-solid coupling,and the interaction between the control valve and the pipeline,the flow pipeline-regulating valve system is prone to vibration instability,which seriously affects this important industrial transportation control process.Security and stability.Existing research often ignores some important non-linear factors that affect pipeline vibration characteristics,and the focus of research is mostly on straight pipes.The research on the nonlinear dynamic characteristics of complex pipeline systems is limited,and most of the control valves are not-The overall analysis of the fluid pipeline system fails to reveal the nonlinear coupling vibration mechanism of the entire system of the regulating valve and the fluid pipeline.This article fully analyzes the complex mechanism of pipeline vibration,and aims at the shortcomings that the transfer matrix method can only solve linear problems and one-dimensional problems.The discrete-time transfer matrix method of multi-body systems is used to establish spatial flow straight pipes,elbows,and branches.The nonlinear transfer matrix model of pipes,variable cross-section pipes,complex space pipelines and fluid pipeline·regulating valve systems predicts the dynamic response of spatial fluid straight pipes,spatially complex pipeline systems,and fluid pipeline-regulating valve systems And the law of vibration.First,a micro-element analysis is made on a straight pipeline conveying fluid in space.The micro-element of the pipeline is divided into structural unit and fluid unit.Based on the Timoshenko beam theory,the deformation of the micro-element is regarded as the superposition of bending,torsion,and shear deformation.The nonlinear vibration model of the straight pipe conveying fluid is presented.Subsequently,the transfer matrix and dynamic response of the system are derived based on the Galerkin method and the multi-rigid-flexible discrete-time transfer matrix method.The vibration time domain diagram,phase diagram and Poincare cross-section diagram of the system.The results show that with the increase of the basic flow velocity,the vibration form of the straight pipe gradually changes from stable to period-doubling bifurcation,and finally chaos appears.This part of the research enriches the relevant theories of spatial pipeline modeling and verifies the possibility of pipeline instability at higher flow rates.Secondly,according to the discrete idea,the mechanical model of the complicated space pipeline is simplified,and the transfer matrix of the elbow,branch pipe and variable cross-section pipeline are respectively derived according to the equilibrium conditions of the discrete model.By combining the transfer matrices of each piping element,the transfer matrix of the complex piping system is obtained,and the nonlinear dynamic response of the complex piping system under the excitation of periodic pulsating flow with different velocity amplitudes is solved.Finally,the control valve and the pipeline are integrated into a whole system,and its stability under the excitation of different periodic pulsating flow rates is analyzed and calculated,and compared with the control valve model without considering the influence of the pipeline.The result shows that the control valve vibrates in the pipeline.The phenomenon of chaos easily appears under excitation,and this influence law is more significant when the valve opening is small.The results of the thesis better reflect the nonlinear dynamic characteristics of the space conveying straight pipe,among which the modeling solution of the space conveying elbow,branch pipe,variable cross-section pipe and complex piping system has a certain reference to its nonlinear research Significance,the analysis of the control valve-fluid pipeline as a whole system reveals the coupling vibration mechanism between the two.In addition,the article applies the multi-body system discrete-time transfer matrix method to the problem of fluid conveying pipelines,which provides a certain idea for the application of this method in the field of fluid conveying pipeline vibration.The modeling results can predict the steady-state and transient response of the system.It provides theoretical guidance for restraining and reducing system vibration.