Fatigue analysis of Francis Turbines with different specific speeds using site measurements

As a result of the variable demand on the energy market, hydraulic turbines have to operate at off-design conditions more and more frequently. Therefore Fatigue analysis becomes increasingly important in the design phase of Francis turbine runners. These Prototype Francis runners suffer from strong vibrations induced by high pressure pulsations at off-design operating areas. Fatigue and damage may be caused by dynamic stress on the runner blades, especially within part load conditions. Therefore, this paper presents the fatigue analyses of two prototype Francis runners based on strain gauge site measurements.