To study the solid-liquid two-phase flow features in the clearances between guide vane end surfaces and casing, as well as the erosion condition of two end surfaces, the unstead three-dimensio-nal flow in a cylinder and a backward-facing step flow channel, which is a simplified model of the end clearance flow in a real hydro-turbine guide vane, was numerically simulated based on the RNG k-ε turbulence model and discrete phase model(DPM)in Fluent. In simulations, the solid particle vo-lume fractions were 1%, 5%, 7% and 10%, the particle diameters were 0.020, 0.050, 0.075 and 0.100 mm, and different inlet velocities were used. Through steady numerical simulations, the distribution of average erosion rate on the upper and lower end surfaces was obtained, and the erosion pattern and locations were analyzed. The results indicate that the distribution of average erosion rate in flow field is closely related to the physics models and the parameter settings for the two-phase flow. With increasing inlet liquid velocity and particle volume fraction, the average erosion rate augments. The erosion positions mainly are located in the front of the cylinder, the reattachment point downstream the step and the outlet of the step. The maximum average erosion rate is about 2.0×10-6 kg/(m2·s). With increasing particle diameter, the average erosion rate decreases due to an increasing inertial force. When the particle diameter is less than 0.020 mm, heavier erosion occurs in comparison with the rate at large diameters, particularly, the maximum average erosion rate is about 2 times the rate at 0.100 mm particle diameter.
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