Numerical Simulation of Turbulent Flow through a Francis Turbine Runner

Three-dimensional turbulent viscous flow analyses for a Francis turbine runner are performed by solving Reynolds averaged Navier-Stokes equations closed with the realizable k-epsilon turbulence model. The discretization is carried out by the finite element method based FVM on a patched block-structured grid system. The boundary conditions for the turbulent properties are treated with a particular attention. In a new research view, CFX-TASCflow software are used to calculate the 3D unsteady turbulent flow in a model Francis turbine runner and to simulate the 3D turbulent flow field in it. The results at the design operating condition are presented in this paper. They show that the flow field structures and the characteristics of swirling flow and its developing process in the Francis turbine can be well predicted. It can be concluded that the results are able to provide important guidance for the hydraulic design of a Francis turbine or its optimization.