Computational fluid dynamics modelling and experimental study of erosion in slurry jet flows

Abstract

The main objective of the present work is to show that one can use computational fluid dynamics (CFD) to predict the flow patterns and particle impact profiles on a specimen and use such data together with phenomenological erosion models to predict both the total erosion rates and the erosion patterns on surfaces. The surface wear-out pattern from profilometry measurements and the total weight loss data of the eroded material were obtained from experiments to validate the model predictions. In the experiments, four different parameters, viz. the impingement velocity, impingement angle, sand concentration and properties of target materials were varied. Their effect on the total weight loss and the erosion patterns are investigated. Two different experimental conditions were used – viz. one in which the specimen and the jet were submerged and the other in which both were exposed (non-submerged). Experimental studies show that total weight loss has a power-law relation with respect to impingement velocity or sand concentration. The weight loss decreases as the hardness of material increases, but not in a linear fashion. Two corrosion resistance materials, 304 stainless steel and chrome white alloy, showed the same corrosion and synergism weight loss although their hardness was much different, 190 HV (Vickers hardness) for 304 stainless steel and 763 HV for chrome white alloy. This implies that the corrosion and synergism weight loss is mainly dominated by the chemical composition of the material and not by its mechanical properties. The results also differ substantially for the submerged and non-submerged cases. When the specimen and the jet were submerged, the erosion scar was typical ‘W’ style. But when sample and jet were not submerged, the scar was much flatter. A phenomenological erosion model that results in a simple algebraic equation has been developed, and the predicted results are in reasonable agreement with the experimental measurements. When they are used locally together with the CFD predictions of the flow field, the agreement with the erosion patterns and the total weight loss is improved significantly.

Keywords:

• erosion modelling
• liquid–solid slurry flow
• jet impingement
• profilometry measurement

Acknowledgements

The authors acknowledge the financial support from COURSE, Syncrude Canada Ltd. and NSERC-CRD grants. The authors thank the assistance of Mr. Tim Revega of Syncrude R & D in the experimental set-up and operation.