Numerical Simulation And Optimization Design Of Erosion Failure Of Bent-pipe Based On Fluid-solid Coupling

Erosion wear widely exists in industrial pipeline transportation systems such as petroleum,chemical industry,water conservancy,etc.The liquid-solid two-phase flow with solid particles and corrosive media will cause wear and corrosion of pipeline transportation system,which will bring huge economic losses to enterprises and huge potential safety hazards.Elbow is a typical part of pipeline transportation system,and its erosion wear occurs.It is also the most serious.Therefore,the accurate study of the flow field and erosion characteristics of liquid-solid two-phase flow in elbow section can predict the failure of pipelines and equipment,and has important engineering and practical significance for the study of elbow erosion.In this paper,taking the erosion failure of 302 stainless steel elbow in pipeline as an example,the effects of physical parameters such as flow rate,pipe diameter,particle diameter and pipe curvature radius on the erosion failure of the elbow under different working conditions are studied by numerical simulation.Aiming at the inner part of 90 degree elbow,three-dimensional software Pro-E is used to establish physical models of different pipe diameter parameters.Structured meshing is carried out by ICEM software.Using DPM in Fluent,erosion simulation analysis of sand-containing liquid-solid twophase flow in elbow section is carried out under different media physical parameters.Pressure,velocity and velocity at 0.5m/s,1m/s,3m/s,5m/s,7m/s,9m/s flow velocities are obtained.The results show that the maximum pressure,maximum velocity and maximum shear force increase parabolically with the increase of fluid medium velocity;the maximum erosion rate of elbow increases with the increase of flow velocity,and the erosion rate increases greatly at high flow velocity;with the increase of elbow diameter,the erosion rate decreases sharply,but under the top pipe diameter,the erosion rate increases comparatively.Slow;when the velocity and other external conditions are fixed,when the particle size is small,the erosion rate increases gradually,but the trend is slow.When the particle diameter reaches a certain value,the erosion rate increases more obviously with the increase of particle diameter;with the increase of bend diameter ratio,the erosion rate decreases gradually,and with the increase of curvature radius,the erosion rate on the side wall of the elbow decreases gradually.Gradually decreasing.Using a set of self-designed elbow scouring experimental device,the experiment was carried out by using the method of inserting patches(7 on the outside and 5 on the inside)at different angles of the elbow wall.The erosion amount at different positions on the inside and outside of the elbow section could be obtained by weight loss method,and the actual working conditions of the elbow section(diameter of the elbow tube is 25 mm,flow velocity is 1 m/s,particle volume fraction is 1%)were simulated.Comparing the experimental value with the erosion amount at the corresponding position of the elbow section according to the simulation,and analyzing the surface morphology of the erosion sample,it can be seen that the most serious erosion area of the elbow section is the joint of the elbow section and the downstream straight section of the elbow,which coincides with the most serious erosion area of the experimental data.Combined with ANSYS Workbench software,the failure of elbow section is analyzed.The results show that with the increase of flow velocity,the relationship between equivalent strain,equivalent stress,total displacement and flow velocity of elbow is parabolic increasing.Then,according to the results of numerical simulation and the failure situation of elbow section,the optimization of elbow is put forward by adding blind through pipe and folding plate,and changing the turning angle of elbow.