Research On Residual Life Of Surface Cracks Pipes Based On FSI

With the development of China’s oil and gas exploration technology natural gas has become an indispensable source of energy for industrial production.In order to meet the energy needs of industrial production long-distance pipeline mixing technology has been widely used.Gas collection pipeline is often large area span,long distance,long use cycle.The pipeline will inevitably appear cracks,corrosion and other defects,these pipes in the course of the internal pressure and internal fluid flow will be affected by the internal pressure and fluid state changes will have a great impact on the pipeline will have a certain impact,especially the fluid flow state The pressure applied to the wall when the change is bound to change,when the pressure changes in the crack defects in the pipeline focus on the fragile link will cause the pipeline fracture.In this paper,the pressure change caused by the gas-liquid two-phase flow is studied in detail,and the stress state and the residual life law of the crack pipeline are summarized under the pressure of the gas-liquid two-phase pipeline.In this paper,the finite element method is used to model the fluid and cracked gas gathering pipeline by ANSYS WORKBENCH.The fluid-solid coupling effect of the fluid with the pipeline structure under different conditions is simulated.The effects of the fluid flow rate at different flow rates and different water contents The influence of the change of the flow state on the stress of the pipeline and the stress state under the action of the different crack size under the flow field.Finally,the residual life of the cracked gas trap is analyzed numerically.The static pressure generated by the fluid domain increases from 871.84 Pa to 1402.64 Pa when the inlet velocity increases from 4/s to 5m/s when the moisture content is 20% under different initial conditions.The holding speed is 5m/s unchanged,moisture content increased from 20% to 70%,the pressure within the fluid domain increased from 1402.64 Pa to 4980 Pa.The stress field of the crack tip increases with the increase of inlet flow velocity and volume fraction by fluid-solid coupling.It is found that under the action of fluid,due to the decrease of the natural frequency of the coupling effect pipe,when the flow rate increases,the natural frequency of the pipeline decreases,and when the external excitation may be in the lower excitation Frequency of the pipeline resonance;when the natural gas pipeline in the higher water content,the higher the natural frequency of the pipeline.The residual life of the crack is analyzed.The initial form depth of the crack is the main factor affecting the remaining life.The fatigue life is calculated by the analytical method in the pipeline cleaning condition.When the crack length is constant,the depth ratio is bigger,The shorter the life span.Through the consideration of fluid velocity,water content and pressure,the crack propagation behavior is the result of the interaction of each factor.Compared with the change of flow rate,the water content of the fluid has a greater effect on the crack propagation.