Cavitation resistance of turbine runner blades at the hydropower plant 'Djerdap'

Abstract

Hydropower plants need to develop means of protection of turbine and hydromechanical equipment from undesirable occurrences, such as degradation of parent material and/or weld metal of parts and structures caused by stresses and unpredictable influence of vibrations, fatigue, corrosion, erosion and cavitation. Results of tests that refer to the cavitation resistance of turbine runner blades made of cast steel 08X15H4 pi M pi, in accordance with GOST standard are presented in this paper. For the testing of cavitation resistance, the ultrasonic vibration test method is used (with the stationary sample), for which it is necessary to measure the mass loss during specified time intervals, while the cavitation resistance of the material is being defined, taking into account the incubation period and cavitation rate. Scanning electron microscope analysis is carried out to study the morphology of sample damage due to cavitation. The obtained results show that the tested steel has a good cavitation resistance and that fatigue is the main failure mechanism.