Evaluation of the jet distortion by sediment erosion in the needle in the Pelton turbines

Abstract

Abstract In order to succeed in the transition to a more renewable energy sector, the hydropower industry must overcome multiple challenges in the coming decades, including the need for faster and reversible turbines to support emerging renewable energy sources. In addition, the location of new projects in tropical and semi-tropical areas poses unique considerations, as does the increase in sediment. Evaluating sediment erosion in turbines is a critical challenge, which may partly be addressed by analyzing the behavior of water jets from eroded nozzles in Pelton turbines. This paper presents an evaluation of the quality of the jet under various hydraulic conditions, focusing on needle erosion. The study is part of a research project conducted in the Waterpower Laboratory at NTNU, focusing on Pelton turbines. Furthermore, this paper investigates erosion patterns caused by sediments on the needle and explores the impact on jet performance. Through high-speed visualization and image processing, the behavior of a jet from the needle tip to a representative distance downstream has been investigated. The investigation revealed discernible differences between jets with eroded and uneroded needles in size and edge variation.