Study on Wear Evolution Characteristics of Sediment in Francis Hydro-Turbine Based on Erosion Coupled with Dynamic Meshes
Under the condition of sediment-laden flow,there is an interaction between sediment particles and turbulence in the hydro-turbine.The dynamic process of sediment erosion will wear the surface of the flow passage components of the turbine,thereby affecting the hydraulic performance and safe operation of the turbine.The evolution process of sediment particle erosion and wear in the whole channel of Francis hydro-turbine is numerically simulated by using erosion coupled with dynamic meshes of DPM(Discrete Phase Model).By comparing the characteristics of the turbulent field under single-phase and solid-liquid two-phase flow conditions,the effects of different sediment mass flow rates and sediment particle shapes on the erosion position,erosion deformation and wear rate with erosion time of the vane and runner are analyzed.The results show that after sediment injection,the overall flow pattern in the draft tube is improved,the turbulence degree is significantly weakened,and the turbulent kinetic energy of the runner can be reduced by 84％-90％compared with the clean water condition.The nose end of the stay ring and the upper and lower ends near the leading edge of the stay vane have deformation and wear marks,the cutting wear occurs at the head of the guide vane upstream,and the water inlet edge of the runner blade near the lower ring has obvious erosion wear.The erosion deformation of the guide vane is greater than that of the stay vane,and the wear rate of the working surface of the runner blade is significantly higher than that of the back surface.With the increase of sediment mass flow rate,the erosion deformation and wear rate of guide vanes and runner blades increase proportionally,and the wear rate shows pulsating characteristics.The erosion deformation of non-spherical particles is larger than that of spherical particles,after 24 hours of erosion on the working surface of guide vanes and runner blades.This study can provide theoretical basis and practical reference for the maintenance,repair,safe and stable operation of hydraulic units in muddy rivers.
Francis hydro-turbineDiscrete phaseErosion coupled with dynamic meshesSediment erosionNumerical simulation
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