The Multiphase flow behavior in an oil production pipe with the convergent-divergent structure is analyzed via computational flow dynamics (CFD) methodology. Based on the mechanism of flow-structure interaction, the location undergoes the high risk of erosion-corrosion is predicted and then the structural improvement for the pipe is proposed. The results showed that the maximum wall shear stress and oil phase fraction both locate approximately 38 mm away from the end of convergent structure. The numerical prediction agrees well with the actual failure instance. It is also found that if the conjunction structure is changed from the right angle to the 1:4 chamfer, the vortex region is eliminated. Accordingly, the maximum wall shear stress is reduced to lower than the critical value of carbon steel. As a result, the erosion-corrosion caused by multiphase flow may be prevented and the operation reliability of the pipe is improved.
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