Research On Large Deformation Flow-induced Vibration Of A Rotating Pipe Conveying Fluid

Due to its simple and light structure,convenient installation,and mature technology,the pipe conveying fluid is often applied to different industrial fields such as aerospace,nuclear industry,and marine engineering.The fluid-solid coupling of the pipe under the environment and internal fluid often causes pipe instability and vibration,which greatly threaten the safety and reliability of the pipeline.Therefore,studying the flow-induced vibration in the pipe conveying fluid has practical engineering value for understanding the dynamic characteristics of the beam pipe,further understanding the pipeline vibration and maintaining the stability of the pipeline.At the same time,using diverse methods to model the pipeline system has a certain academic value.The research of the pipeline in this thesis mainly includes the following aspects:(1)Use the absolute node coordinate formulation and the extended Lagrange equation suitable for non-material-containing bodies to establish the dynamic equations of the rotating pipe conveying fluid.The dimensionless frequencies of pipe at the angular velocity and the flow velocity are calculated separately,and the critical velocity of the pipe conveying fluid at a different pipe and fluid mass ratios are calculated.The Newmark-β method was used to calculate the dynamic response at different flow velocity.The results show that during the rotation of the pipe,due to the influence of the fluid flow velocity,the pipe will have a certain bending deformation,and as the angular velocity increases,the bending deformation will also be greater;as the flow velocity increases,the bending deformation will also be greater(2)Based on obtaining the rotating pipeline,the motion equation of the rotating cantilever pipeline containing concentrated mass is derived.The natural frequencies under the influence of angular velocity,flow velocity,and position and size of concentrated mass are calculated respectively,and the critical velocity of the fluid in the concentrated mass of different weights at different positions is calculated.The dynamic response of the concentrated mass at different positions and weight at different angular velocity and flow velocity is calculated respectively.The results show that: when there is concentrated mass,angular velocity,flow velocity,masses at different positions,and mass sizes will all cause the frequency of the system in turn.The closer the concentrated mass is to the end,the smaller the critical flow velocity of the system,the greater the vibration amplitude of the system,and the smaller the deformation after stability.(3)The vibration equation of the cantilevered pipe conveying fluid containing the piezoelectric sheet is established,and the dynamic response of the pipe system has been calculated at the different parameters of the piezoelectric.The results show that the length of piezoelectrics and the active voltage have some influence on the amplitude of the pipeline after the pipeline is unstable.In this thesis,through the research of the rotating flow pipe,its dynamic equation is established and the vibration frequency and response analysis are carried out,which provides a model reference for the control of pipe vibration.