Prediction method for cavitation erosion based on measurement of bubble collapse impact loads

The prediction of cavitation erosion rates is important in order to evaluate the approximate life of components in fluid machinery. The measurement of impact loads in bubble collapses helps us to predict the life under cavitation erosion. In this study, we carried out the erosion tests and measured impact loads in bubble collapses with a cavitating liquid jet apparatus which complies with the ASTM G134-95 standard. The bubble collapse impact loads were measured by a piezo ceramic transducer in a cavitating liquid jet apparatus. To produce various cavitation conditions, the flow velocity was changed from 184 down to 80 m/s. We evaluated the incubation period based on a cumulative damage rule by measuring the impact loads of cavitation acting on the specimen surface and using the “constant impact load - number of impact curve” similar to the modified Miner's rule which is employed for fatigue life prediction. We found that the parameter ∑(Fiα×ni) (Fi: impact load, ni: number of impacts and α: constant) is suitable for the evaluation of the erosion life. After the constant α has been obtained under two different cavitation conditions, we can predict the incubation period with the cavitating liquid jet method under yet another condition, provided that the bubble collapse impact loads are measured.