Characterization Of Wear Characteristics In Water Pipe By CFD-DEM Coupling

Pneumatic transport is a mode of transport of materials through fluid driven particles in a closed pipe,which has many advantages such as simple equipment,safety and efficiency.Gaseous transport is a form of fluid carrying other phases of particles as a carrier fluid,when the two-phase flow moves in the pipe,will have friction with the tube wall and then cause severe wear at the elbows,and long-term,it will lead to the breakage of the pipe and even fracture,which will cause great safety hazards and economic losses to the production transportation.At present,the research focused on wear is still staying on empirical prediction and there is no accurate and detailed calculation formula,but with the rapid development of computer simulation technology,the specific operating condition can be targeted simulation analysis by computer modeling.In this thesis,the CFD-DEM coupling method was used to model and simulate the numerical simulation of the pipe gas-solid two-phase flow containing the particles of single and polydisperse systems.Focused on the effect of different particle size distribution on the corrosion properties of the pipe wall punch corrosion,and the analysis of the kinetics and mechanism of the wear formation of the tube wall unfold.This is mainly studied from three aspects: the state of motion of the two-phase flow inside the water pipe and the wear law,the wear characteristics of the water pipe under different parameters and the analysis of two-phase flow containing particles with different particle sizes.The results showed that:(1)The two-phase flow formed a high velocity flow region on the inside of the convoluted tube and a low velocity flow region on the outside of the convoluted tube;Where the maximum wear point occurs in the intersection of the straight pipe segment extension and the elbow,with secondary flow phenomenon occurring,producing a "" Y-shaped "" wear area;(2)The pressure difference between the inside and outside of the pipe will decrease continuously as the angle of the tube is increased,the pressure on the inside of the tube will decrease as the angle of the tube is increased,the pressure on the outside wall of the tube will drop during the process when the angle is 120 °,the area of the largest wear area will decrease as the angle of the tube is increased,however it will have less effect on the wear area;The maximum wear volume increases and the total wear volume increases with the increase of gas velocity,and the impact force of the particles on the elbow is significantly larger when the gas transport speed is increased;The direction of gravity will not affect the wear volume,but will cause the maximum wear position to shift toward the direction of gravity;(3)When single particles with different sizes are contained in the pipe,the wear will increase with the size of the particles,and small particles will cause more secondary wear areas;The size of wear experienced by the pipe was dominated by large particles,while the total amount of wear experienced by the pipe slowly increased with the addition of small particles.After analysis,it is found that with the increase of the number of small particles,the number of large particles collide on the wall surface decreases.The results will provide a theoretical basis for better prediction of the situation of the corrosion wear inside pipe in processes such as gas force delivery,in the hope of truly assisting enterprises to effectively reduce the risk and optimize the production efficiency.