Dynamic Analysis Of Fluid-conveying Pipes Based On Fluid-structure Interaction Simulation Technology

Fluid-transporting pipes are widely employed in practical engineering,and their vibration behaviors induced by fluid-structure interactions display rich dynamic characteristics.In this thesis,the fluid-structure interaction(FSI)simulation technology is utilized to explore the dynamics of fluid-conveying pipe under different working conditions and configurations.The main research contents are as follows:1.In order to verify the simulation model of fluid-structure interaction method,the simulated results were compared with theoretical and experimental results respectively.in this way,the Galerkin method and Absolute Node Coordinate Method(ANCF)were used to theoretically investigate the dynamics of the straight and curved pipe conveying fluid,respectively.In addition,experimental study on cantilever straight pipe was carried out.The linear and nonlinear vibration behaviors obtained by theory and experiment are compared to those by FSI to verify the accuracy of the FSI simulation model.2.Considering the viscosity characteristics of the fluid,the phenomenon of turbulence induced vibration of the semicircular pipe with both supported ends was revealed.The SST k-? turbulence model was used to describe the transient flow field in the pipe,and the variation of the flow field pressure and velocity was analyzed.The effects of flow velocity,dynamic viscosity and other parameters on the vibration behaviors of the curved pipe were quantitatively analyzed.It is found that the vibration amplitude increases with the velocity growing,however the vibration amplitude decreases with the dynamic viscosity growing;The turbulent viscosity and Reynolds shear stress term on the pipe's random vibration are revealed.3.The in-plane and out-of-plane vibration characteristics of the straight-bend coupled flow pipe under the conditions of steady internal flow,pulsating flow and water shock are studied.By studying the linear characteristics and nonlinear response of the straight-bend coupled flow pipe,it is found that out-of-plane buckling occurs when the flow velocity reaches 7m/s,and in-plane buckling occurs when the flow velocity reaches 10m/s.The outof-plane modal shape changes with the increase of the flow rate.At the same time,the vibration responses of the straight-bend coupling pipe under different pulsating internal flow were obtained.It is found that the subharmonic resonance occurs when the ratio of the pulsating frequency to the natural frequency is 0.56.In addition,the water shock effect caused by the valve on and off was investigated,and the influence law of the butterfly valve and ball valve on the flow field was obtained.4.The influence of flow field boundary,fluid medium and pulsating flow on the dynamic characteristics of three-dimensional fluid-conveying pipe is studied.By comparing the effect of velocity and pressure inlet boundaries,it is found that the velocity inlet has no influence on the natural frequency of the pipe,while high pressure inlet has a greater influence.However,the increase of velocity will significantly increase the static deformation displacement of the pipe.At the same time,the viscosity and density of the fluid have great influence on the static deformation of the pipe.Under the action of pulsating flow,the three-dimensional flow pipe will vibrate,and the vibration amplitude increases significantly when subharmonic resonance occurs.With the increase of pulsating frequency,the vibration mode will also change.In addition,in order to improve the stability of the three-dimensional pipe,the size and configuration of the pipe structure were optimized.