Investigation on Erosion of Continuous Bending Pipes in Different Directions

Abstract

With the increasing demand for natural gas in the world, ensuring the safety and stability of pipeline transportation of natural gas has become an important subject. Compared with the studies focused on the erosion of single bend, T-pipe, and U-pipe, the studies on the continuous bend in different directions are scarce. In this paper, the model is characterized by three straight pipes with the same length and directions along the Z, Y, and X axes of the Cartesian coordinate system. The numerical simulation of gas-solid two-phase flow under different gas to solid mass ratios in the continuous bent pipeline is carried out by selecting the Oka erosion model. The results indicate that the velocity distribution of the second bend is different from that of the first bend. With the change of flow deflection angle and the accumulation of the centrifugal force, the shape of the velocity contours in the second bend turns from “basin” into a comma and the velocity experiences a process including rapid increase, slow decrease, gradual increase, and steep decrease. When the flow rate is 12.5 m/s, the maximum speed of the second bend is about 5 % greater than that of the first bend. Instead of a “straight-line” shape in the erosion area of the first bend, the second presents a feather shape. As the flow rate increases gradually, the shape characteristics of the feather erosion zone change from short and dense to long and loose. Besides, the maximum erosion rate of the second bend is greater than that of the first even about 1.52 times. Finally, according to the simulation results, the protection suggestion of the continuous elbow is given.