INFLUENCE OF INLET BOUNDARY CONDITIONS IN THE PREDICTION OF ROTOR DYNAMIC FORCES AND MOMENTS FOR A HYDRAULIC TURBINE USING CFD

Paper in proceeding, 2008

The rotordynamic behaviour of a hydraulic turbine is influenced by fluid-rotor interactions at the turbine runner. In this paper computational fluid dynamics (CFD) is used to numerically predict the rotordynamical excitation forces due to the flow through a hydraulic turbine runner. The simulations are carried out for three diffferent boundary conditions. One axi-symmetric inlet boundary condition, and two axi-periodic boundary conditions. The two latter are obtained from separate simulations of wicket gate and spiral casing flow. It is found that the inlet boundary condition significantly affects the rotordynamical forces and moments.