Effect of leakage flow on sediment erosion in guide vane region

Abstract

The erosion of hydraulic turbine components in sediment-laden flows poses considerable operational and maintenance challenges in hydroelectric power generation. The current work is aimed at investigating the sediment erosion of a guide vane (GV), a head cover, and a shaft located within the GV region of a Francis turbine, particularly focusing on the effects of leakage flow. An Euler–Lagrange numerical method is used to predict erosion. Specifically, erosion-induced deformation is also considered by using a dynamic mesh. The distribution and intensity of erosion in the GV region, along with the erosion mechanisms associated with leakage flow, are thoroughly examined. Additionally, the impact of erosion-induced deformation on the flow pattern and erosion itself is analyzed. The results indicate that the head cover, as well as the leading edge of the GV and the shaft, sustains considerable erosive damage. Notably, erosion of the head cover is particularly severe and is exacerbated by increases in the mass flow rate or particle size. The leakage vortex, formed by the interaction of the leakage flow with the main flow in the GV region, is responsible for the severe erosion observed on the head cover. This leakage vortex attracts particles, which repeatedly impact the head cover at high speeds. Furthermore, these particle impacts lead to localized erosion-induced deformation, resulting in pit formation. The presence of the pit alters the flow characteristics near the wall region, causing more particles to collide with the pit and ultimately accelerating the erosion process.