Effects of Hydrodynamic Parameters on Cavitation Erosion Intensity

摘要

A rotating foil apparatus was developed and used to study the effect of exposure time, pressure, velocity and size of the foil on intensity of cavitation erosion. Earlier studies with a vibratory apparatus showed that the rate of erosion increases with exposure time, reaches a maximum value and then decreases. These observations are essentially confirmed for the case of erosion on an actual hydrofoil. The maximum rate of erosion is then correlated with the cavitation parameter for two sizes of NACA 16-021 hydrofoil (3 inches and 1 1/2 inches in chord length). The intensity of erosion increases with decreasing cavitation parameter, reaches a peak and then decreases with decreasing cavitation parameter at a given velocity. An approximate analysis was made to explain this result. According to this analysis, the intensity of erosion should vary as the cube of the velocity and should be independent of the size of the foil. However, the experimental results show that the intensity of erosion varies as the sixth power of the velocity and also depends on the size of the foil. An understanding of these two scale effects is essential for a successful model-prototype correlation. (Author)