Effects of turbine design parameters on sediment erosion of Francis runner

Problems of sediment erosion in the hydropower industry across Asia and South America have become a major technical challenge. One of the emerging solutions to prevent the erosion of hydro turbines is to reduce the relative velocity inside the runner by improving hydraulic design. It is important to evaluate relation of the turbine design parameters on sediment erosion so as to identify those parameters that can be attuned to reduce the erosion. A new design program named as “Khoj” has been developed to facilitate this study. A method to include sediment erosion as a design parameter is devised. The traditional design of Francis runner has been made for a reference case. Each hydraulic design parameter is varied within a pre-defined range and changes in erosion relative to the reference design have been evaluated. It is found that the runner outlet diameter, peripheral velocity at inlet, and blade angle distribution have the highest effect on sediment erosion of Francis runner. Results of this study can be utilized to develop better Francis turbines to handle sediments.