Coalesced effect of cavitation and silt erosion in hydro turbines-A review

Cavitation is a phenomenon which manifests itself in the pitting of the metallic surfaces of turbine parts because of the formation of cavities. However, silt erosion is caused by the dynamic action of silt flowing along with water, impacting against a solid surface. The erosion and abrasive wear not only reduce the efficiency and the life of the turbine but also cause problems in operation and maintenance, which ultimately lead to economic losses. Researchers have studied that the cavitation in silt flow is more serious than in pure water. However, the coalesced effect of silt erosion and cavitation is found to be more pronounced than their individual effects. In the present paper the studies in this field carried out by various investigators are discussed and presented. Parameters related to the combined effect of cavitation and silt erosion which are responsible for efficiency loss due to erosion as investigated by researchers have also been discussed. (C) 2014 Elsevier Ltd. All rights reserved.