Modelling of flow-induced stresses in a Francis turbine runner

This study presents the results of large scale modelling of the water flow and the analysis flow-induced stresses in a Francis turbine runner. The modelling undergoes two stages. The first stage deals with the water flow that has been investigated by using Computational Fluid Dynamics (CFD) in order to identify the loads acting on the turbine blades. At the second stage, the finite element analysis of stresses has been performed based on the pressure distributions calculated from CFD modelling. The operational data recorded at Unit 2 of the Derbendikan power station have been used as input in the modelling. The results of calculations have revealed that the zones of high stress are situated at the trailing edge of the turbine runner, which explains observed fatigue cracks in these areas.