Abstract: Hydraulic machineries running on muddy rivers suffer from sediment erosion that often causes deformation and damage to flow components, seriously threatening the safe operation of hydropower plants. This study conducts an experiment on a rotating jet facility to examine the influence of sediment concentration on the impact abrasion and erosion characteristics of hydraulic machinery materials, using the weight loss method and Scanning Electron Miscroscopy (SEM). The results show the cumulative weight loss of materials from impact abrasion and erosion takes a nearly linear increase with the rise of sediment concentration. With sediment concentration lower than 60 kg/m3, the increase in the cumulative weight loss of the tested three material is gradual; it becomes rapid at higher concentration. As the concentration increases, the impact erosion causes more severe damage to the materials, but cavitation erosion shows a weakening trend. The higher the surface hardness of the material, the better its resistance to cavitation erosion, and the lower the critical sediment concentration at which the weights of abrasion and erosion are equal. Flow cavitation affects the angle at which sand particles impact on the material surface, and it usually increases the horizontal impact load of the particles. The abrasion marks show lip edges and material accumulation, and the sand particle cutting damage dominates at higher sediment concentrations.

Key words: sand abrasion, erosion, hydraulic machinery materials, rotating jet facility