Numerical Simulation Of Multiphase Flow Erosion In A Bend Pipe Under Vibration Condition

With the continuous development of China’s oil industry,a large number of oil resources have been developed,of which the exploitation of thick oil has gradually become popular.When transporting thick oil,the economical and effective water ring transportation method is often used,during which some sand impurities are often mixed with thick oil to flow in the pipeline and erode the pipe wall,resulting in serious erosion areas will cause damage to the pipeline failure,leading to oil leakage in the pipe,thus causing damage to the ecological environment.At the same time,the pipeline is often in a complex marine environment,which is affected by external excitation such as wave force,internal waves and earthquakes to produce shaking,which aggravates the erosion of the pipeline.Based on the above reasons,it is meaningful to study the erosion of multiphase flow bends under vibration environment.Firstly,a model for numerical calculation is constructed for the horizontal 90° bend,and the VOF method is used to calculate the oil-water continuous flow field,the Realizable k-εturbulence model to calculate the turbulence field,and the Lagrangian model to calculate the motion of discrete particles,and the vibration pressure drop and maximum erosion rate of the bend are verified and analyzed with related literature.The results compare well and meet the expectations.Secondly,the oil-water continuous phase flow field,particle motion,and pipe erosion under different vibration conditions are calculated to investigate the relationship between the flow field and particle motion and erosion.The main research results are as follows:The maximum erosion rate and the total erosion rate increase and then decrease when the amplitude increases and the serious erosion area is on the outside of the bottom of the elbow and the outside of the bottom of the connected straight pipe section,and the maximum erosion position is at the bottom of the 45° section of the elbow,and the particles are subject to the action of secondary flow and gravity in the form of collision and slip on the pipe wall;the maximum erosion rate and the total erosion rate increase significantly when the amplitude increases with constant frequency,and the serious erosion area is at the maximum erosion position is at the top position of the outer side of the 90° section,and the particle motion is in the form of collision motion.Finally,the erosion law under the coupling of various factors and vibration was investigated.The main research results are as follows:The maximum erosion rate produced by vertical vibration,and the maximum erosion area is located at the bottom of the 45° area of the elbow corner;the maximum erosion rate produced by the bend in the H-H flow direction is the largest among the three flow directions,and the maximum erosion area at the elbow is located at the bottom of the 45° area of the elbow corner;the greater the flow velocity in the pipe the greater the erosion rate,and the maximum erosion area at the elbow is located at the bottom of the 30° position of the elbow,and at the same flow velocity with the vibration The greater the mass flow rate of the particles,the greater the maximum erosion rate,the more serious wear area of the elbow is at the bottom of the elbow 30°～45° area,and the erosion at the same mass flow rate grows and then decreases at different vibration frequencies,and the erosion at different amplitudes rises with the growth of amplitude,at a mass flow rate of 1.2 kg/s and a vibration condition of 10 kg/s.The maximum erosion rate is maximum at the mass flow rate of 1.2 kg/s and vibration condition of 10 mm 40 Hz;the maximum erosion rate decreases with the increase of particle size in the flow rate higher than 3 m/s,and the serious wear area of the elbow is at the outer bottom of the elbow angle 60°～90°,and the erosion rate increases and then decreases with the increase of frequency and continues to increase with the increase of amplitude,and the maximum erosion rate increases at the particle size of 400 μm and vibration condition of 10 mm 40 Hz.The maximum erosion rate was found at the particle size of 400 μm and vibration condition of 10 mm 40 Hz.