Numerical investigation of mass loading effects on elbow erosion

• Mass loading increase may cause reduction in the penetration ratio.
• Interparticle collisions must be accounted for even at low mass loadings.
• Interparticle collisions can protect elbows from particle erosion.
• The cushioning effect can be predicted numerically.

Wear due to particles is often the key factor for pipeline failure. In this work, the effects of different sand particle concentrations on the erosion of an elbow pipe are investigated numerically. In order to assess the quality of the numerical predictions of the erosion rate, experimental data were first used to validate the erosion and restitution models at low concentration. The input parameters for the empirical erosion correlation were obtained from accurate CFD models for the gas–solid flow within the bend. One, two and four-way couplings were evaluated at different mass loadings. In general, it was found that even at low to moderate mass loadings, the effects of inter-particle collisions on the penetration ratio cannot be neglected. Another important finding is that the maximum penetration ratio gradually diminishes as the mass loading increases. As counterintuitive as it may appear, this phenomenon has actually been observed in experiments and is named cushioning effect. Based on the analysis of the simulation results, it can be concluded that a layer of particles builds up adjacent to the elbow wall, protecting it from direct particle collisions. Conversely, the inter-particle collisions damp the particle impact to the surface, therefore reducing the penetration peak.

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