Comparative CFD analysis of Kali-Gandaki “A” Francis runner with runner generated from Bovet method

Abstract

Kali-Gandaki “A” is a medium head Francis turbine site located in Syangja District of Nepal. The dimensionless specific speed number for this site falls in the range suitable for generating meridional profile from Bovet Method. In this paper, the meridional profile of the actual runner currently deployed is extracted from CAD drawings and another meridional profile is generated using empirical relations of the Bovet Method. Meridional area of profile from Bovet Method is significantly larger in comparison to CAD-based profile. Both of these profiles are imported in commercial software ANSYS BLADEGEN, using linear blade angle distribution with no lean runner’s 3D model is generated for both cases. Both designs are meshed in Turbo-Grid and simulated in ANSYS CFX with k-epsilon turbulence model. Simulation reveals the CAD-based runner has 91.11% efficiency in comparison to Bovet based runner which has only 85.6% efficiency. Also, Simulation results reveal Bovet-based runner is more susceptible towards erosion and cavitation which suggests there is room for improvement and optimization of design obtained from Bovet Method.