Gas–solid Two-Phase Erosion of Multi-Elbow Relief Line under Supercritical Condition

The Eulerian-Lagrangian method was used to establish a numerical model of a multi-elbow pipeline erosion and examine the erosion of the relief line elbow under supercritical conditions. The model was used to examine the effects of the discharge volume, sand content, and shape factor of sand on multi-elbow erosion and those of the connection length on double-elbow erosion. The erosion mechanism and law of multi-elbow lines under gas-solid two-phase flow conditions were revealed. The results indicated that the most severe erosion of the elbow occurred on the impact surface. However, the erosion area of the multi-elbow was relatively long. In a multi-elbow pipeline, the maximum erosion rate of the outlet elbow was 84 times that of the inlet elbow. For the multi-elbow pipeline, the erosion rate was related to the discharge volume, sand content, particle shape, and length of the connection between elbows. The erosion rate of the elbow at the outlet decreased gradually and stabilized with an increase in the connection length.