Stability And Dynamic Response Analysis Of Vertical Submarine Pipeline

With the improvement of offshore drilling technology in China,oil and gas drilling and transportation technology equipment has been gradually applied to the deep sea field.Submarine pipeline is an important pipeline equipment in offshore oil and gas exploration.Vortex induced vibration of submarine pipeline caused by flowing seawater is the main factor to reduce the mechanical properties of submarine pipeline and accelerate the fatigue failure of submarine pipeline.Once the submarine pipeline structure is damaged,it will be damaged In addition to causing great economic losses,the leaked oil and natural gas will also cause catastrophic damage to the marine environment.Therefore,it is of practical significance to study the vibration and flow field characteristics of submarine pipelines in different environments.In this paper,the study of vertical pipeline is carried out by numerical simulation.The nonlinear theory and the basic hydrodynamics theory are used to calculate the vibration characteristics of the vertical long-distance pipeline under the sea floor by using the fluid-solid coupling analysis technology and ANSYS finite element method,The vibration law and the flow field around the vertical pipeline under different working conditions are obtained.This paper compares the vibration and the drag coefficient of pipe rise under the influence of the coming flow,and compares with the results of domestic and foreign scholars,and verifies the accuracy of the model.Through the numerical simulation of the pipeline under different Reynolds numbers,the flow field characteristics around the pipeline and the variation law of the pipeline vibration trajectory are obtained,and the vibration mode inducement of the pipeline is analyzed,The special physical phenomena such as vibration mode change,wake vortex flow law and phase switching of the pipeline are captured under the phenomenon of vortex induced vibration.The vibration characteristics of the pipeline and the motion law of the surrounding flow field are discussed when different inflow velocity,different pipe wall,different pipe length,different constraint conditions(fixed constraint,soil constraint,hinge constraint)and whether the vibration eliminator is added;The results show that the larger the incoming velocity,the thinner the wall thickness and the longer the span length of the pipeline,the worse the stability of the pipeline.At the same time,the stability of the pipeline under fixed constraints,soil constraints and hinge constraints will increase in turn.Based on the calculation results,a kind of vibration eliminator is designed.This kind of vibration eliminator can effectively eliminate the vortex generated by the wake of the pipeline flowing in the sea water,effectively eliminate the vortex shedding phenomenon,thus reducing the vibration of the pipeline.The effectiveness of the vibration eliminator is verified by numerical analysis.Through the modal analysis of the vertical pipeline,the theoretical support is provided for the analysis of reducing and eliminating the resonance of the pipeline Bracing.It is proposed to The stability of high pipeline provides a theoretical reference.