Numerical Study of Sediment Erosion of a Francis Turbine with change in guide vane design

Abstract The guide vane is a primary component influencing the sediment erosion of the turbines. For the current work, Francis turbine installed in the Bhilangana-III hydroelectric plant is numerically modelled to investigate the effect of guide vane design on turbine erosion. The existing guide vane profile has been modified to adopt an unsymmetrical hydrofoil shape. Two numerical models of the scaled turbine are developed using the commercial code ANSYS CFX. The first model is prepared with the existing guide vane, whereas the second model incorporates the modified guide vane. The erosion rate density is determined using a modified Grant and Tabakoff erosion model for different operating conditions and a sediment concentration range of 500 – 2500 PPM. The turbine with modified guide vanes showed a reduction in wear of guide vanes and runner by 12-23 % in comparison to that of the existing guide vanes. Further, the erosion is higher for both the part and high load conditions as compared to the best efficiency point operation.