The Fluent software is used to simulate the flow field distribution at downstream of the sudden expansion pipeline. By changing the inlet velocity and the pipe expansion ratio

the distribution law of the mass transfer coefficient at downstream of the pipeline under different conditions is obtained. Based on the established mathematical model

the change laws of the mass transfer coefficient and corrosion rate at downstream of the sudden expansion tube with the inlet velocity and pipe expansion ratio is obtained. The results show that

when the inlet velocity is constant

the mass transfer coefficient and corrosion rate at downstream of the sudden expansion pipe increases with the sudden expansion ratio

and the peak position moves to the flow direction.When the pipeline sudden expansion ratio is constant

the mass transfer coefficient and corrosion rate at downstream of the sudden expansion pipeline increase with the velocity

and the peak position moves to the downstream of the pipeline. The simulation results are basically consistent with the experimental results.