Influence of sediment particle size on wear characteristics of Kaplan turbines
To understand and clarify the sediment wear attributes of Kaplan turbines,a certain power station turbine was taken as the research object,and a numerical investigation of solid-liquid two-phase flow was carried out based on the Eulerian-Lagrangian multiphase flow model.The central focus centered on elucidating the influence of sediment particle size on both erosion rate and distribution across the turbine components.Research findings show that the high-risk region for sediment erosion is near the wheel rim of the blade pressure side and the suction side.With increasing sediment grain size,erosion intensifies on the blade pressure side while diminishes on the suction side,leading to a gradual contraction of this erosional region towards the proximity of the wheel rim.Particles are influenced by the leakage vortex,forming strip-shaped erosion scars along the rotation direction on the wall of the runner chamber.The erosion rate gradually decreases in the draft tube cone section,the differences in the degree of wear in different outlet flow passages increase and the sediment particles form belt-like spiral erosion scars along the extension direction of the leakage vortex in the cone section.During the Kaplan turbine operation,the draft tube section experiences the most substantial erosion followed by the runner and the runner chamber.Prolonged turbine operation under conditions of excessively small or large sediment diameters should be avoided,and during maintenance,particular attention should be paid to the sediment wear of the runner blades and the runner chamber.By identifying high-risk region of sediment erosion during the operation of the Kaplan turbine,a reference is provided for the quantita-tive analysis of sediment wear in various flow passage components.It helps in scheduling maintenance intervals for the turbines and provides a theoretical basis for further optimization in the design of Kaplan turbine.
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