Research on the Length Ratio of Splitter Blades for Ultra-high Head Francis Runners

The flow field of ultra-high head Francis runner with different length radio splitter blades was simulated. The calculating process was based on continuity equation and Navies-Stokes equation and S-A turbulence model was used to make the equation group closed. The control equation was discretized by finite-volume method and SIMPLIC method was applied to solve the equation. Through calculation, the efficiency and the flow field of the runners with different length radio splitter blades at different points was obtained. It was found that the efficiency are higher when length radio is between 60% to 75% and when the radio is more than 75%, the cavitation performance became worse at design point and large discharge point.