Recent developments in the optimization of Francis turbine components for minimizing sediment erosion

Abstract

Sediment erosion in hydraulic turbines are severe in case of hydropower plants operating in Himalayan Rivers of Nepal. Francis turbine components are heavily eroded while hard particles as quartz flow along with water through the water conduit in power plant. In Francis turbines, the runner blades where significant portion of hydraulic energy converts in mechanical energy are heavily eroded. This is due to complexity in fluid flow while operated at different operating conditions with sediment contained water. Conventional design of Francis turbines has overlooked on the effects of sediment erosion while considering optimum efficiency at all operating conditions. This paper examines multi-objective optimization of a reference 92 kW model Francis runner for minimizing sediment erosion effects. The model turbine studied in this paper is a scale down model turbine of Jhimruk Hydropower Plant, Nepal that is severely affected by sediment erosion. It was found that sediment erosion was reduced significantly at part load, full load and best efficiency point with improvement in hydraulic performance for model turbine utilizing multi-objective optimization on runner blade design.