A numerical study on the performance characteristics of low head Francis turbine with different turbulence models

Abstract

A Francis hydro turbine can be used in large as well as small hydro power plant. Due to complex flow phenomenon in turbine, deriving a hydrodynamic behaviour of flow through experimentation is a tedious job. These phenomena such as flow separation around turbine blade, pressure drop in runner and draft tube, etc. can be captured through a numerical study. A numerical approach needs turbulence modelling to capture fluctuating component of flow variables. In view of that, a comprehensive study has been carried out to find the sensitiveness of various turbulence modelling on the stability of numerical solution. In present study, three different turbulence models such as Standard k-ε, Standard k-ω and SST model have been considered. To carried out this study, three different loading conditions have been chosen i.e. part-load, BEP and over-load condition. This study has been carried out by using ANSYS CFX (18.1) CFD solver.It has been observed that at part-load condition, Standard k-ε model performed better as compared to other model but at other loading conditions SST model delivered accurate results. Also, turbulent nature of flow at the outlet of runner is well captured by SST model.