Hydro-abrasive erosion modelling in Francis turbine at different silt conditions

•Field measurements of hydro-abrasive erosion in Francis turbine components in a medium-scale hydropower plant in India.•Analysis of operating and silt conditions like discharge, head, velocity, silt concentration, particle size, and mineral compositions.•Estimation of erosion depth and efficiency losses in Francis turbine as per IEC 62,364 for the operation period FY 2018–19.•Calibration of site-specific parameters of IEC 62,364 erosion model for selected site conditions.•Computation of Erosion rate and efficiency loss at part load and design load. Hydro-abrasive erosion creates problems for the safe and effective running of hydropower projects. This is of even greater concern in hilly regions. The huge losses in the revenue of the hydropower plant have become a burden on the hydropower project developers. These losses are mainly due to the reduced capacity of the generation of electricity units (kWh). The high amount of silt entering the plant, especially in the monsoon season causes heavy hydro-abrasive erosion in the turbine and other underwater components. The deterioration of underwater plant equipment due to this kind of erosion can also lead to a total shutdown of the hydropower plant. In the current scope of the study, efforts have been made to validate the existing erosion models for the Francis turbine with the operational hydropower plant and carry out the numerical erosion modelling in the Francis turbine to predict the turbine efficiency losses at maximum and part-load conditions. Various developed erosion models are analyzed for the study period of FY 2018–19 based on influencing parameters like silt concentration, silt size, hardness, and site-specific flow constant. The site chosen for this purpose was the MB-II hydropower plant, a 304 MW hydropower project having four generating units of Francis turbine located at the foot of the Himalayan hills in the Uttarkashi district of Uttarakhand, India. The calibration factor is calibrated for the MB-II hydropower plant using GRG Nonlinear algorithm using a multi-start solver.