The influence of disc friction losses and labyrinth losses on efficiency of high head Francis turbine

Abstract

CFD is a very powerful tool, which significantly reduces the need for model testing of Francis turbines. Numerical models are constructed so as to cover all the essential geometric and physical properties of the physical models. However, for the sake of simplicity, some geometric details are often neglected. In case of Francis turbines, labyrinths are usually not included in the numerical model and consequently the disc friction losses and labyrinth losses are ignored. This may lead to inaccurate prediction of turbine efficiency. In our study we have investigated the importance of considering all the geometrical details of labyrinth for the accurate prediction of efficiency of high head Francis turbine. The research was performed by using commercial software Numeca FINE™/Turbo.