Sediment erosion of hydraulic turbines is a significant challenge in hydropower plants in mountainous regions like the European Alps, the Andes, and the Himalayan region. The erosive wear of Pelton runner buckets is influenced by a variety of factors, including the size, hardness, and concentration of silt particles; the velocity of the flow and impingement angle of the jet; the properties of the base material; and the operating hours of the turbine. This research aims to identify the locations most susceptible to erosion and to elucidate the mechanisms of erosion propagation in two distinct designs of Pelton runner buckets. The Pelton runner buckets were subjected to static condition tests with particle sizes of 500 microns and a concentration of 14,000 mg/L. The buckets were coated with four layers of paint, sequentially applied in red, yellow, green, and blue. The two Pelton buckets, $D_1$ and $D_2$, were evaluated for their erosion resistance properties. $D_2$ demonstrated superior erosion resistance, attributed to its geometrical features and material composition, lower erosion rates, less material loss, and improved surface integrity compared with D1. This difference is primarily attributed to factors such as the splitter’s thickness, the jet’s impact angle, the velocity at which particles strike, and the concentration of sand. $D_2$ exhibits a great performance in terms of erosion resistance among the two designs. This study reveals that the angle of jet impingement influences erosion progression and material loss, which is important to consider during a Pelton turbine’s design and operating conditions.

Pelton turbine is an impulse turbine that converts kinetic energy of incoming jet of water into mechanical energy. Due to impingement of high-speed jet on buckets, Pelton turbine experience high stress at the tip of bucket and at the connection of bucket and rim. To provide the structural strength to the runner, a hoop is attached to it which allows better distribution of forces. However, the impact of hoop on the hydraulic performance of runner is important to assess. For this, a numerical analysis based on Computational Fluid Dynamics has been performed on both traditional and hooped Pelton runner. Transient analysis has been done to calculate the efficiency of both runners under same boundary conditions. The analysis was performed at different openings of needle. Numerical study showed that the efficiency of hooped Pelton runner is less compared to traditional Pelton runner at higher and medium openings. However, at lower openings hooped runner is more efficient. The efficiency drop was in the range of 3.56% to 1.25%. Flow contours reveal that obstruction of fluid is more prominent at higher opening than lower openings, which is the main reason for efficiency drop. Hoop, despite giving structural strength to the runner, is detrimental to the hydraulic performance of traditional runner.