Time dependant measurements of cavitation damage

Due to the extremely long length of experiments, in most studies of cavitation erosion only damage in the incubation period is measured and the final damage (mass loss rate) is then predicted by extrapolation. The methods of extrapolation are usually very basic since there were almost no in depth time dependant measurements of cavitation erosion performed in the past. A rotating disc test rig that generates a very aggressive cavitation and pure copper specimens, as erosion sensors, were used to investigate the correlation between the damage within the incubation period and final mass loss. The damage was measured optically three times during the incubation period and by weighing the specimen during the rest of the experiment. The results confirmed that the same clear relationship between the damage in the incubation period and the final mass loss rate exists, what means, that the mass loss rate can indeed be qualitatively predicted on the basis of measurements performed within the incubation period. This is a good basis for developing laws of extrapolation from a short time scale (laboratory measurement within the incubation period) to the real time scale (machine operation).