Numerical and Experimental Investigations of Sediment Erosion in the Pelton Wheel Turbine Buckets

Abstract

Sediment erosion-corrosion is a critical threat to the safe operation of hydro turbines, which may lead to component damage or even complete failure of the turbine. The mechanism of sand erosion is ambiguous and not yet fully understood by researchers and manufacturing industries. A lack of understanding of the mechanism of sand erosion is a barrier to developing an erosion model to exactly quantify sand erosion in the Pelton turbine. If the components damaged due to erosive wear are left untreated for a long time, it may result in a complete breakdown of the Pelton turbine. The preeminent objectives of this research work are to determine parameters that influence sand erosion, identify erosion-prone areas in Pelton turbine buckets, quantify the erosive wear quantitatively and numerically, determine the impact of erosive wear on surface roughness and 3D profile of Pelton bucket, and analyze the microscopic mechanism of sand erosion. Five Pelton buckets made of aluminum, carbon steel, stainless steel, polylactic acid (PLA), and acrylonitrile butadiene styrene (ABS) were used to perform erosion experiments under two-phase, solid-liquid flow conditions. Four different flow velocities, 20, 35, 45, and 60 m/s, and three different particle sizes, 150, 200, and 300 μm were used in erosion experiments. Multi-layer paint modeling technique was used to identify erosion-prone areas. Optical profilometry was used to perform surface roughness analysis and evaluate the microscopic degree of damage due to erosive wear in the Pelton bucket. High-resolution Scanning Electron Microscope (SEM) was used to analyze the microscopic mechanism of sand erosion and perform energy-dispersive X-ray spectroscopy (EDS) analysis. Mass loss and thickness reduction analysis was performed to quantify the erosive wear. Future work and limitations in this research field are recommended for researchers and manufacturers.