Abstract Hydraulic turbines experience severe operational and maintenance challenges when operated in sediment-laden water. The combined effect of erosive and abrasive wear in turbine components deteriorates their life and efficiency. The quantity and pattern of sediment erosion depends on the nature of the flow and the amount of hard minerals contained in water. Localized erosion patterns are observed mostly in guide vanes, runner blades and facing plates of Francis turbines due to different natures of fluid flow in those regions. Accelerating flow around the guide vanes and its shaft causes abrasive and erosive wear in its surface, which causes increase in the size of the clearance gap between the facing plates and the guide vanes. Flow leaving the clearance gap forms a vortex filament due to the leakage from high pressure side to the low-pressure side of the guide vane, which eventually strikes the rotating runner blades. This paper presents a case study of a power plant in India with low specific speed Francis turbines, which is severely affected by sediment erosion problems. A numerical analysis of the flow is conducted inside the turbine to study causes of various erosion patterns in the turbine components. The results from CFD are compared with the actual erosion in turbines. Erosion in guide vanes and runner blades are taken into consideration in this paper, due to the complex flow phenomena around these regions. It is found that the leakage flow through clearance gaps of guide vanes is the primary cause of erosion at the inlet of the runner blades. Furthermore, the effects of size and shape of quartz particles are studied which shows that erosion is directly proportional to these parameters.

中文翻译：

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低比速弗朗西斯涡轮机中的沉积物侵蚀：影响和原因的案例研究

摘要 水轮机在富含沉积物的水中运行时会遇到严峻的操作和维护挑战。涡轮机部件中侵蚀性磨损和磨料磨损的综合影响会降低其寿命和效率。泥沙侵蚀的数量和模式取决于水流​​的性质和水中硬矿物质的数量。由于这些区域中流体流动的不同性质，局部侵蚀模式主要在弗朗西斯涡轮机的导叶、转轮叶片和面板中观察到。围绕导叶及其轴的加速流动导致其表面的磨蚀和侵蚀磨损，这导致面板和导叶之间的间隙尺寸增大。由于从导叶的高压侧泄漏到低压侧，离开间隙的流动形成涡流丝，最终撞击旋转的转轮叶片。本文介绍了印度一家发电厂的案例研究，该发电厂配备了低比速混流式水轮机，该发电厂受到沉积物侵蚀问题的严重影响。在涡轮机内部对流动进行数值分析，以研究涡轮机部件中各种侵蚀模式的原因。将 CFD 的结果与涡轮机中的实际侵蚀进行比较。由于围绕这些区域的复杂流动现象，本文考虑了导叶和转轮叶片的侵蚀。研究发现，通过导叶间隙的泄漏流是导致转轮叶片入口处腐蚀的主要原因。此外，