Abstract: Adaptive renovation have been done to a Francis turbine to enhance the matching of the unit to the hydrological conditions of the power station, improve the hydraulic efficiency, increase the unit power output, and promote the stability and safety of the unit. Taking No.3 unit of Bailianhe Hydropower Plant as the research object, a new optimization design method aiming at improving the efficiency and operating stability for Francis turbine runners is applied in this paper. For this unit, 3D CFD simulations of its whole flow passage are conducted to predict its hydraulic performance and internal flow characteristics. The hydraulic characteristics and the operation stability of the runner after adaptive renovation has been analyzed by field test. As for hydraulic characteristics, experimental results showed a efficiency rise of 5.0% to 8.8% for the optimized runner which operated in the power outputting range of 7.0 to 14.5 MW. As for the operation stability, at the partial load condition, pressure pulsations at the spiral case inlet and the draft tube inlet are reduced significantly after the optimization of the runner. Results from both the numerical simulation and the experimental study proved the effectiveness of our new optimization design method of the Francis turbine runner.

Key words: Francis turbine, adaptive renovation, numerical simulation, field tests, operating stability