SEDIMENTATION IN HYDROELECTRIC POWER TURBINES

Abstract

The primary cause of erosive wear and energy loss is friction, and reportedly, one-third of the world’s energy resources go to overcome friction by several methods. The presence of deposits in water is a common problem in mountainous regions and some Ukrainian hydroelectric power stations. Hydro turbines face serious issues related to erosion from deposits during operation. Erosive wear occurs due to the impact of solid particles against a solid surface. The current environment contains particles whose velocity is sufficient to damage metal surfaces. Various researchers have conducted numerous studies to minimise the effect of deposit erosion in multiple locations of Francis turbine components (FT). For this purpose, they performed field investigations, experimental measurements, empirical modelling, computational fluid dynamics (CFD) work, and other methods. Various empirical models have been used to describe erosive wear in terms of material and fluid properties. They established that, for ductile materials, maximum erosion occurs at an impact angle of 30°, whereas for brittle materials, it occurs in the range of 80–90°. In the literature, various experimental methods are available to quantitatively assess slurry erosion, such as the rotating disk apparatus (RDA), slurry tank testing, jet erosion testing, and rotating drum testing. Due to manufacturing technologies used in mechanical processing processes, the exposed surface has a certain absolute roughness that increases during machine operation due to abrasion or erosion. Therefore, surface texture leads to increased energy efficiency losses during operation. Technological advancements have facilitated the widespread use of computational tools to address deposit erosion issues. In recent decades, numerical methodology has been a widely used and effective tool, yielding tangible and reliable results. This study examines potential methods for detecting and reducing deposits. This type of erosion depends on flow characteristics, surface properties, and properties of the eroding material. The article provides comprehensive information on sedimentation (deposits) causing wear in hydraulic turbines. Keywords: hydroelectric turbine, sedimentation erosion, computational fluid dynamics, fluid-structure interaction.