Analysis Of Vibration Characteristics Of Pipeline Under Fluid-structure Interaction Based On Workbench

In the pipeline system,the structural vibration of the pipeline wall,the pressure fluctuation of the liquid,and other fluid-structure interaction vibrations of the system will produce noise pollution,cause the components of the pipeline to fall off,and serious leakage and damage will occur.Studying the vibration characteristics of pipeline under fluid-structure interaction can provide important reference for the design safety of pipeline system.In this paper,the vibration characteristics of straight pipes with variable cross section and tees under fluid-structure interaction are calculated and analyzed.The specific research contents and results are as follows:The fluid-structure interaction vibration mechanism,vibration analysis model and vibration analysis method of the pipeline are specifically summarized.The specific concepts of finite element analysis are described in detail,and the linear structure analysis theory,dynamic analysis theory,and fluid analysis theory are specifically studied.The numerical analysis process of pipeline fluid-structure interaction problems on ANSYS Workbench and CFX software is summarized,and the application of each method in this paper is discussed exhaustively.Models of straight pipe with gradually changing section and straight pipe with abruptly changing section are established.Numerical simulation is performed using the finite element analysis software ANSYS Workbench to calculate the natural frequencies and mode shapes of first six orders of two straight pipes with variable cross section and analyze the effects of the outer diameter of the right pipe,the pressure of the water inlet,the flow velocity of the water inlet and the wall thickness of the pipeline on the natural frequency of the pipeline.The results show that,in the natural frequency of the same order,the straight pipe with gradually changing section is slightly higher than the straight pipe with abruptly changing section.In the research range of the outer diameter of the right pipe,the pressure of the water inlet,the flow velocity of the water inlet,and the thickness of the pipeline,the natural frequencies of the two straight pipes with variable cross section decrease with the decrease of the outer diameter of the right pipe,and increase with the increase of the pressure of the water inlet and the flow velocity of the water inlet,and decrease with the increase of the wall thickness of the pipeline.Under the conditions of the change of the outer diameter of the right section of the pipe,the pressure of the water inlet,the flow velocity of the water inlet and the wall thickness of the pipeline,the natural frequency increase of the straight pipe with abruptly changing section is larger than that of the straight pipe with gradually changing section,and it is more susceptible to these factors.Models of double-inlet and single-outlet tee and single-inlet and double-outlet tee are established.Numerical simulation is performed using ANSYS Workbench to calculate the natural frequencies and mode shapes of first six orders of two fluid flow modes of tee and analyze the effects of water inlet pressure,water inlet velocity and the wall thickness of the pipeline on the natural frequency of the pipeline.The results show that,in the natural frequency of the same order,the double-inlet and single-outlet tee is slightly higher than the single-inlet and double-outlet tee.In the research range of the pressure of the water inlet,the flow velocity of the water inlet,and the thickness of the pipeline,the natural frequencies of the two fluid flow modes of tee increase with the increase of the pressure of the water inlet and the flow velocity of the water inlet,and decreases with the increase of wall thickness of the pipeline,decrease significantly with the increase of the wall thickness of the pipeline in the first three stages,and increase first and then decrease with the increase of the wall thickness of the pipeline in the fourth to sixth stages.Under the conditions of the change of the pressure of the water inlet and the flow velocity of the water inlet,the natural frequency of the double-inlet and single-outlet tee is more susceptible to the influence of inlet pressure changes than the single-inlet and double-outlet tee,but both are not easily affected by the flow velocity of the water inlet.Under the condition of the wall thickness of the pipeline change,the natural frequency of the first three orders of the double-inlet and single-outlet tee and the natural frequency of the fourth to sixth orders of the single-inlet and double-outlet tee are larger,which is more susceptible to the influence of the wall thickness of the pipeline changes.