Sediment erosion in guide vanes of Francis turbine operating in Himalayan rivers

Abstract

Guide vanes are stationary component in Francis turbine that performs periodic movement though a pivoted support, in response to the change in flow or load. To allow this movement, small gaps are provided at top and bottom of vanes, called clearance gap. They are internally lined with replaceable or metal claded linings called facing plates. Operational point of turbine is determined by this movement, which regulates amount and direction of flow to runner. In presence of sediment flowing with water, significant erosion occurs which affects life and performance of turbine. It has been observed that vane faces, leading edge, trailing edge and clearance gaps were severely eroded. Which in turn enhances flow friction and secondary flows. This affects performance of entire Francis turbine. Guide Vane erosion can be controlled by suitable selection of vane profile. This study focuses of erosion phenomena, its effect and solution measure focused in guide vanes.