OPTIMUM DESIGN OF THE FRANCIS TURBINE WITH LARGE HEAD VARIATION USING CFD APPROACH

摘要

It is hard to make a little progress in water turbine stability problem at all times. More attention is paid to this problem in the hydropower plants are of high head and large head variation. The vibration problem always puzzles most of large hydraulic power plants have been developed to different extent. The hydraulic problem is one of very important factors to induce vibration. In this paper, the numerical calculations based on CFD approach were carried out for 22 different points of operation, to modify the model turbine consists of spiral casing, tandem cascade with 20 channels, runner and draft tube. And then a comparative test was carried out. With respect to the modified turbine, the occurrence of vortex rope under part-load condition and the appearance of stall in blade pressure and suction surfaces were delayed. The results of optimization design are in good agreement with experimental measurements, and indicate that the turbine is characterized by superior hydraulic performance.