Sediment and Cavitation Erosion in Francis Turbines—Review of Latest Experimental and Numerical Techniques

Abstract

Sediment and cavitation erosion of the hydroelectric power turbine components are the fundamental problems in the rivers of Himalayas and Andes. In the present work, the latest research conducted in both the fields by various investigators and researchers are discussed and critically analyzed at different turbine components. Analysis shows that both types of erosion depends on flow characteristics, surface, and erodent material properties. Design optimization tools, coalesced effect (CE) of sediment and cavitation erosion and well conducted experiments will yield results that are beneficial for erosion identification and reduction. Although some researchers have done experimental work on the coalesced effect (CE) of sediment and cavitation erosion, very limited Computational Fluid Dynamics (CFD) work is available in literature. The present research work will be beneficial for practitioners and researchers in the future to address the erosion problem successfully.

A Case Study: Sediment Erosion in Francis Turbines Operated at the San Francisco Hydropower Plant in Ecuador

“…Quartz is typically the predominant mineral found in most rivers, while in this study, plagioclase minerals composed the greatest part of the sediments found in Pastaza River. Nevertheless, the hardness values did not seem to differ significantly from other studies [10][11][12]14]. Comparing the shape of the sediments with the sample chart, the sphericity and roundness were found to be S = 0.7 and R = 0.3, respectively.…”

“…He proposed changing the opening of the guide vanes to improve turbine efficiency and reduce the erosion rate [13]. Moreover, Noon and Kim discussed and analyzed the latest experimental and numerical techniques to determine sediment and cavitation erosion on different turbine components using baseline data from the Tarbela Dam hydroelectric project in Pakistan [14]. However, all the aforementioned studies were performed in Asia, and no research on the topic has been performed on South America, where similar erosion issues are found.…”

Numerical Investigation of Flow Behaviour and Erosion Potential in the Side-Wall Clearance Between Guide Vane and Runner

“…There can be three types of side-wall clearance between guide vanes and runner i.e., guide vanes being above the level of the runner (clearance type 1), runner being above the level of the guide vanes (clearance type 2), and both the runner and the guide vanes being in the same level. In Francis turbine, operating in sediment-laden flow, erosion concentrations were observed in the region of the GV and the runner blade [11,12]. More importantly, sever erosion was observed in side-wall clearance region of Francis runner as shown in Figure 4.…”

Wear Behavior of Epoxy Resin Reinforced with Ceramic Nano- and Microparticles

“…This affects energy production and environmental protection since hydroelectric power is frequently used due to its commonality and significant contribution to total energy production [1]. The degradation of turbine blades caused by erosion processes such as cavitation and sediment erosion produces a challenge and an additional cost associated with energy production [2]. Cavitation is the process of the formation of vapor bubbles in low-pressure regions within a fluid, produced when the hydrostatic pressure acquires a value lower than the saturation vapor pressure [3].…”

“…Although cavitation or erosion studies often utilize both numerical and experimental methods, relying solely on numerical techniques may seem efficient, yet it disregards crucial factors. Numerical methods, while time-and resource-saving, encounter challenges stemming from various parameters [2,6,7]. These parameters interplay, where temperature fluctuations within the liquid flow impact pressure fluctuation amplitudes and wave velocities [8,9].…”