Derivation of Complete Performance Characteristics of a Low Head Prototype Francis Turbine Using CFD

Abstract

Design of the well optimized Francis turbines is a great challenge, even today, as it requires a deep insight into intricate flow features through the turbine. In this regard, CFD has evolved as a promising tool which now has become an essential integral of hydraulic turbine design. In the present work, complete performance characteristics of a 48 m head prototype Francis turbine has been derived using commercial CFD code ANSYS CFX. A complete assembly of the turbine consisting of spiral casing, stay ring, distributor, runner, and a draft tube is considered for a steady state flow simulation. For computation of the flow field, K-ω based shear stress transport (SST) turbulence model along with high-resolution advection scheme and turbulence numerics are implemented. For validation, computed efficiency values for different load regimes are compared with the corresponding experimental values and a fair agreement is found between the two.