Numerical simulation on effect of connection pipe length between elbows on erosion of π-shaped pipeline

The connection pipes between the elbows of π-shaped pipelines can affect the movement of particles and the fluids, thereby greatly influencing the erosion of the elbows. Hence, the erosion of the gas-solid two-phase flow to the pipelines was simulated numerically with the Fluent software, and the erosion distribution and the changing law of erosion rate in the elbows of π-shaped pipelines under different connection pipe length were analyzed. The results show that the fourth elbow of the π-shaped pipeline was severely impacted by pitting corrosion, up to 5-10 times of other elbows. In addition, the variation of the length of the connection pipes would cause the change of the movement track of the solid particles, thus affecting the erosion distribution and the erosion rate of each elbow in the π-shaped pipelines. Definitely, with the increase of the length of the connection pipe, the erosion rate of the first three elbows changed little, but that of the fourth elbow decreased observably. When the length of the connection pipe increased to more than four times of the pipe diameter, the erosion rate of the fourth elbow decreased to 1/4-1/3 of that with the elbow connected directly, and the severity of pitting corrosion was reduced significantly. Generally, the research results herein could provide the theoretical guidance to the design, and maintenance of the π-shaped pipelines.