Numerical Study on Sediment Erosion of Francis Turbine with Different Operating Conditions and Sediment Inflow Rates

Abstract

Francis turbines are thought to be good solutions for both small and large-scale hydro power plant so, they have been used widely to produce power from the water sources. The turbines can be subject to erosion when the turbines operate in sediment-laden water. The erosion can reduce the performance, changes in flow pattern and even breakdown of turbine. To prevent this erosion in turbine components, predicting the region of erosion might be very useful for developing coating techniques and optimization of hydraulic design of the turbine components. In this study to predict the sediment erosion of Francis turbine runner with different operating conditions and sediment concentrations, Tabakoff and Grant model was used and erosion rate was calculated. In order to figure out the effect of different operating conditions, simulations were conducted at best efficiency and full load condition. Also, to investigate the effect of sediment inflow rates, inflow rates were varied with the value of 1, 5, 10, 20, 30, 40 and 50 kg/s. The predicted erosion patterns were similar for both operating conditions and mainly found on the pressure side of runner blades. Most of the erosion was thought to occur near the outlet side of runner due to high relative velocity for both best efficiency and full load condition. It was also found that erosion rate increased almost linearly on increasing sediment inflow rate regardless of the operating conditions.