Analysis of discharge flow and losses from an eroded Pelton bucket components

The online evaluation of the erosion level of hydraulic turbines in hydropower plants is one of the current challenges in the energy sector. Offline inspections and measurements procedures require several hours, reducing the energy production. The necessity of more effective methods to assess the integrity of the turbines is growing at the hydropower plants. The research to understand the behavior of the flow over buckets can provide insight into the condition of the Pelton turbine. This study focuses on evaluating the differences between the flow discharge from an eroded and non-eroded bucket. The analysis consists of evaluating the change of reflection angles on the spread of the flow besides the torque measure on the shaft connected to stationary buckets in different positions at different stages of erosion. The image processing considered thousands of frames to average the angles of reflection. The use of a high-speed camera was necessary to minimize edge distortion in the flow. A difference of 15 degrees was found between the reflection angles from a non-eroded and full eroded bucket at the first selected position of the bucket-jet interaction. Regarding the efficiency measure between the hydraulic energy on the jet and the torque transfer from the bucket to the shaft, A 1.5% decrease was found at certain angles between eroded and non-eroded bucket also. Therefore, the analysis of the reflection angles gives some insight into the erosion level on Pelton buckets that could serve for future studies of online monitoring systems.