Unsteady Computational Fluid Dynamic Analysis of the Behavior of Guide Vane Trailingâ€گEdge Injection and Its Effects on Downstream Rotor Performance in a Francis Hydroturbine

Abstract

A unique guide vane design, which includes trailingedge jets, is presented for a mixedflow Francis hydroturbine. The water injection causes a change in bulk flow direction at the inlet of the rotor. When properly tuned, altering the flow angle results in a significant improvement in turbine efficiency during offdesign operation. Unsteady CFD simulations show nearly 1% improvement in overall turbine efficiency with the use of injection. This revolutionary concept also has the ability to reduce the intensity of the rotor–stator interactions (RSI) by compensating for the momentum deficit of the wicket gate wakes. This technology may be equally applied to other turbomachinery devices with problematic rotor–stator flow misalignments.