Experimental Study Of Corrosion Rules Of Typical Pipe Fittings For Water Based On The Flow Field Changing

The problem of leakage in urban water supply pipe network not only affects water supply security,and also causes a huge waste of energy and resources.As one of the main causes of network leakage,pipeline corrosion could make a "secondary pollution" risk.Thus the research on characteristics of pipe fittings for water corrosion behavior play an important role in developing strategies of water supply security,such as evaluation of pipeline corrosion resistance and service life.Based on the method of computational fluid dynamics simulation(CFD)of flow field,this study starts from operating conditions of water supply network,then measured and analyzed behavior of typical pipe fittings for water in different flow field,finally summarized relationship between the corrosion characteristics and flow field distribution.This study hope could provide theoretical basis for the development of some pipeline anti-corrosion measures.The main contents and results are as followings:(1)Using fluid dynamics software,selected flow rate of 0.5m/s,1.0m/s,1.5m/s as conditions,and completed numerical simulation of the flow field of pipe,determined the distribution of velocity,pressure,shear stress in straight pipe of inlet,elbow,and straight pipe of outlet,and on the basis of analysis and comparison of the characteristics of the flow field,determined the study points in electrochemical measurement of dynamic corrosion on typical pipe fittings for water at last.(2)Designed and built a test platform for electrochemical measurement of dynamic corrosion,by which under flow rate of 0.5m/s,1.0m/s,1.5m/s,made a 144 h open circuit potential and corrosion current density monitoring on the study points,and found that as the flow rate increases,the open circuit potential has a negative shift phenomenon,which could significantly increased the corrosion rate,at the end of experiment on each flow rate,the impedance spectrum was measured and its results further show the study points with a low flow rate may have low corrosion rate and indeed are easier to form a more stable resistance film.(3)On analysis and comparison the velocity and shear stress distribution of the study points,results of electrochemical measurement indicates that pipeline corrosion more likely to occur on the both inside of elbow and straight pipe of outlet.