Study of silt erosion mechanism in Pelton turbine buckets

In the present study, an experiment was carried out to investigate the mechanism of erosion of a small scale Pelton turbine, under actual flow conditions. Samples of silt were collected from the head work of one of the most silt affected hydro power station in India. Silt parameters (silt particle size and silt concentration) were considered to investigate the mechanism of silt erosion on Pelton turbine buckets for different silt sizes. In the first part of the experimentation, hot spots (spots which are more prone to erosion) were identified under a high silt concentration. Second part of the experimentation was carried out to study the erosion mechanism for small specimens of metal which were fixed at the marked hot spots. Based on the investigation, it has been found that silt size is a strong parameter to produce erosion and the material removal from the surface is due to plastic deformation and ploughing of surface. ► The sediment present in the water exerts force on the turbine components; as a result the turbine components get deformed. ► The mechanism of erosion is different in different parts of a Pelton turbine bucket. ► The present study is undertaken to investigate the mechanism of erosion in the highly eroded parts of Pelton turbine buckets.