Research On Resonance Characteristics Of Fluid Conveying Pipeline Under Fluid-solid Couplin

The vibration of the pipe wall and the pressure pulsation of the fluid in the pipeline can cause a large amount of radiation noise in the system and even lead to fatigue failure of the system.The excitation source can be mechanical excitation or fluid excitation.This paper aims at the continuous mechanical disturbance of rotating pipelines for rotating equipment and takes the pipeline as the research object.According to potential flow theory,structural dynamics and fatigue noise theory,finite element analysis of ADINA potential fluids is used to simulate the fluid-structure interaction.The resonance characteristics of the self-vibration and the continuous harmonic excitation of the lower pipeline are studied.Based on this,resonance fatigue and noise research are continued.The main work is as follows:1.Using ADINA to establish a finite element model of the pipeline,through the potential fluid element to simulate the fluid-structure interaction between the structure and the fluid in the pipeline.Taking the simplified pipeline as the research object,the effects of different flow velocities,outer diameter of the pipe,thickness of the pipe wall and restraint method on the natural vibration characteristics of the system were studied,and the influence of grid density on the calculation accuracy was considered.Comparing the calculation results,some conclusions with reference value were obtained.2.Simulate the continuous mechanical disturbance of the pipeline by rotating equipment.A three-dimensional dynamic analysis model of the pipeline was established to study the influence of different amplitudes and frequencies on the resonance characteristics of the pipeline under continuous harmonic excitation.Analysis and response results show that there is almost no high-order resonance problem in the pipeline,and in the safety design,only the first order natural frequency is avoided.3.On the basis of dynamic analysis,firstly,perform fatigue analysis to determine the load spectrum and the SN curve of the material under the resonance of the pipeline.According to the Miner linear cumulative damage criterion,predict the fatigue life of the system after the resonance of the system is stable.The results were analyzed;after that,noise analysis was performed and relative noise was analyzed using the relative comparison method.The results show that when the external excitation frequency is the low-order natural frequency of the system,it contributes more to the fatigue problem;when the external excitation frequency is the audible low-order frequency of the system,the contribution of the noise problem is more obvious.The research results in this paper show that the ADINA finite element method can predict the vibration response results of the pipeline,and can change the natural vibration characteristics of the pipeline in the design stage to avoid the first-order resonance.