A Coupling Numerical Simulation Of Physical Erosion-Electrochemical Corrosion In Sand-Containing Saewater Pipeline Flow

Nowadays,in order to build a maritime power and build "One Belt And One Road",seawater pipeline plays an important role in maritime transportation.At the same time,sea water piping is an indispensable part of the structure of naval ships.In extreme Marine environment,pipeline corrosion is a problem that cannot be ignored in both military and civil pipelines.Based on the existing theories of metal erosion corrosion mechanism,the formation mechanism of oxide film after metal passivation,and the electrochemical corrosion mechanism,this paper proposed the erosion corrosion mechanism of metal oxide film and the metal erosion-electrochemical coupling corrosion mechanism,and carried out the numerical simulation of erosion-electrochemical coupling corrosion.Then,according to the existing experiments,the correctness of the model is verified.Finally,an example is given for verification according to the actual situation.The research contents of this paper are as follows:Firstly,the mechanism of physical erosion and corrosion of oxide film after metal passivation is proposed.According to the formation and mechanism of the oxide film under the action of metal passivation,combined with the physical erosion corrosion mechanism,the mathematical model of the damage of the metal oxide film under the action of erosion,which is more suitable for the actual situation,is put forward.Second,the mechanism of metal erosion-electrochemical coupling corrosion is proposed.After the metal oxide film is damaged,the metal is exposed to corrosive liquid.According to the galvanic cell chemical reaction,the metal is the anode and the oxide film is the cathode,forming electrochemical corrosion,which reduces the protective ability of the oxide film and seriously accelerates the metal corrosion speed.At the same time,the erosion effect of sand-bearing seawater still exists,and the continuous erosion of solid sand and gravel causes the destruction of oxide film,which further accelerates the generation of electrochemical reaction.Thirdly,the mathematical model of pipeline erosion-electrochemical coupling corrosion is proposed.The finite element simulation software COMSOL and ABAQUS were used to simulate the movement of seawater and sand contained in it under the action of physical erosion and corrosion.Then,the mathematical model of metal oxide film damage is simulated,and the determination formula of oxide film damage is given.Finally,the polarization of the metal was determined,the electrochemical reaction was carried out,and the mathematical model of erosion-electrochemical coupling corrosion was given.Fourthly,according to the existing erosion-electrochemical corrosion test,numerical simulation verification.Firstly,the experiment is simply described,and then the calculation results of the mathematical model are compared with the experimental results to prove the feasibility of the mathematical modelFifth,according to the actual situation,for instance verification.The finite element model of erosion-electrochemical coupling corrosion was established step by step.The numerical models of sand and gravel erosion in the case of bend pipe and tee pipe are constructed respectively.According to the actual situation of pipeline erosion and corrosion and the previous experimental data,we independently designed the erosion electrochemical corrosion case,and put it into the erosion electrochemical corrosion finite element model.Then,we analyzed the case and discussed the results.Finally,the theoretical and numerical simulation of erosion and electrochemical coupling corrosion of sand-bearing seawater pipelines is carried out in this paper,which plays a certain role in the corrosion evaluation of both civil seawater pipelines and military seawater pipelines.For military sea water pipelines,corrosion prediction of sea water pipelines can be carried out during the voyage to ensure the progress of navigation and combat missions.For civil seawater pipelines,the conveying parts of pipelines can be replaced in time to reduce the risk of oil leakage,reduce Marine pollution and ensure economic benefits.