A review on flow and sediment erosion in guide vanes of Francis turbines

Abstract

Guide vanes in Francis turbine faces frequent erosion due to its operation in sand laden water, which demands focus on design, manufacturing, operation and maintenance of turbines. These vanes are designed on high precision with standard hydrofoils for efficient conversion of pressure to kinetic energy. The erosion on surfaces, upper and lower ends and leading and trailing edges of guide vanes induces cross flow at clearance gaps, tip leakage at trailing edges and high friction on the surfaces, increasing hydraulic losses associated with flow. Review on post erosion hydraulic and mechanical effect on guide vanes and its vicinity are the main objectives of this work. It has been assisted by flow around vanes, field observation of erosion, possible operational problem and method of laboratory estimation of erosion. The vulnerable locations, erosion severity, possible post erosion problems, research gap and possible measures to comprehend them have been focused, which will be useful in further research activities.