逆解法手法と数値流体力学を用いたフランシス水車ランナの最適化設計

抄録

A Francis turbine runner was optimized by a combination of means of the 3D Inverse Design Method and Computational Fluid Dynamics (CFD). An experiment of the directly optimized conventional turbine confirms the validation of CFD calculation. A new meridional shape was designed by Design of Experiments with CFD and the database of meridional shape factors. Angular momentum at the runner inlet was corrected to cover the effects of the boundary layer from runner upstream domains such as stay vanes and guide vanes. Using the meridional shape and the corrected angular momentum and considering the secondary flow mechanism, blade loading distribution and stacking condition were optimized. It led to the decrease of secondary flow energy near the runner inlet and of the runner loss. The full-domain CFD calculation confirms that the total loss of the new turbine at the design point is 4[%] lower than that of the conventional one. This result shows the 3D Inverse Design Method is practical to control the secondary flow in the Francis turbine runners and optimize the shape.