Abstract:
Hydroelectric power is currently one of the largest sources of renewable energy worldwide.
Particularly in Ethiopia, more than 90% of the electrical energy is produced by hydropower in
which the turbine runner is a key component of a hydroelectric turbine responsible for converting
the kinetic energy of flowing water into mechanical energy that can be used to generate electricity.
While doing so, the repeated stress cycles that the turbine runner undergoes during operation can
cause fatigue failure and deformations and then responsible for significant financial and energy
losses.
Fatigue study can be conducted experimentally using real-time measurements of pressure, fluid
flow, and vibration in hydraulic turbines or prototypes. As fatigue tests are time demanding, this
type of fatigue study is expensive and resource demanding. Another technique is through numerical
analysis which is popularly used by researchers due to complex structures of actual machines and
also due to time, cost considerations. Fluid Structure Interaction (FSI) is one such numerical
method which is widely used for flow induced stress study. Therefore, this research has employed
FSI approach with a coupled solution of Computational Fluid Dynamics (CFD) and Finite
Element study (FEA). The commercial software SOLIDWORKS 2022 and ANSYS 19.2 has been
used for Modeling 3D CAD of francis turbine runner and analysing FSI respectively. Using the
results of the FSI analysis, it has been found that the maximum stresses due to the water pressure
are located at the trailing edge of the runner blade towards the transition between the blade and
the crown. This explains why this region has been identified as a critical area for fatigue crack
initiation in the Francis turbine runner. The results also show good agreement with the previous
studies in the literature. It was further observed that the Francis turbine runner considered for this
study has infinite life and minimum damage combined with maximum factor of safety
