Abstract:In order to study the erosion wear phenomenon of the gradual expansion pipe of the sandcontaining natural gas gathering pipeline,the Euler multiphase flow model,fluidstructure interaction model and erosion model of the flow field in the gradual expansion pipe were established by using the ANSYS software.The stress distribution,flow characteristics and erosion effect of the gradual expansion pipe were analyzed and compared with those of the sudden expansion pipe.The flow field characteristics and erosion law of the gradual expansion pipe were analyzed by changing the inlet velocity,particle size and particle mass flow rate.The results show that the stress of the gradual expansion pipe is concentrated on the inner wall surface of the throat and the inner wall of outlet pipe section,and the erosion zone is concentrated on the lower surface of the outlet pipe section and the exit.The erosion zone in the outlet pipe section is in an ellipse,and the erosion zone at the exit shows a “U” shape.The stress of the sudden expansion tube is concentrated on the upper wall of the junction between the inlet pipe section and the outlet pipe section,and the erosion zone is located at the inlet pipe section.The erosion rate of the gradual expansion pipe is increased first,then decreased and then increased with the increase of the inlet flow velocity,increased first,then decreased and then tends to be stable with the increase of the particle size,and increased linearly with the increase of the mass flow rate.Under the same conditions,the maximum equivalent stress of the sudden expansion pipe is 1.73 times of that of the gradual expansion pipe,and the deformation displacement is 1.77 times of that of the gradual expansion pipe.However,the erosion of the gradual expansion pipe is more serious,and the maximum erosion rate is 1.7 times of that of the sudden expansion pipe.