Study On Vibration Characteristics Of High-temperature Steam Pipeline

The steam pipeline is widely used in the nuclear industry and is an important part of the nuclear power system.In the operation process,it may produce stress concentration or damage due to local structural vibration and other reasons,thus affecting the normal operation of the whole power system.Therefore,to ensure the stable and reliable operation of the pipeline system,it is particularly important to study the vibration characteristics of its working state,and the related vibration reduction and isolation research is also the current hot spot.This article focuses on the research on the vibration characteristics of high-temperature steam pipelines.According to the physical structure of the steam piping system,a simplified geometric model of the elbow is established.First,to understand the vibration response of each node of the piping model under continuous load(such as internal pressure,dead weight,and fixed ends at both ends),the steady-state thermal fluid-structure coupling analysis was carried out,and it was found that the secondary flow phenomenon would occur when the fluid flowed through the elbow.In the process of studying the static vibration characteristics of pipelines under different conditions,it is found that the maximum pressure drop,deformation and stress of pipe wall all increase with the increase of fluid velocity,and decrease with the increase of temperature.However,with the increase of the radius of curvature,the stress on the elbow and the pressure drop on the pipe wall show a gradual decrease.Increasing trend;simulation shows that the steam pipeline model is prone to stress and deformation concentration under steady-state conditions is the inner side of the elbow outlet and the vicinity of the elbow inlet.Then the fluid-structure coupling dynamic characteristics analysis of the pipeline is carried out,and it is understood that the simulation results of the pipeline vibration characteristics under the unidirectional and bidirectional coupling have significant differences,and it is necessary to consider the bidirectional coupling.Then the modal analysis of the pipeline found that there is a difference between the natural frequency of the pipeline when the fluid-structure interaction is considered and the natural frequency without consideration,and attention should be paid to the influence of the fluid-structure coupling effect on the natural frequency of the structure.Finally,a geometric model of the steam pipeline of a certain experimental platform was established to study the vibration characteristics of the pipeline structure under two-way coupling.From the harmonic response analysis,it can be seen that the pipeline vibration response is mainly concentrated at low frequencies.In the middle and high-frequency stages,as the frequency increases,the displacement and the acceleration value response gradually weakens.Aiming at the problem of pipeline vibration control,a test-bed was built to test the vibration reduction performance of high-temperature pipeline shock absorber.The vibration reduction performance of three kinds of shock absorbers with different supports was tested and analyzed,and the experimental results were compared with the simulation results,which verified the reliability of the model and the feasibility of the simulation method.The finite element model can be used for further dynamic analysis Research on force characteristics.