Cavitation erosion of aluminum considering bubble collapse, pulse height spectra and cavitation erosion efficiency

Abstract

Water erosion data on 1100-0 aluminum specimens obtained using a cavitating venturi are compared with bubble collapse pulse height spectra measured using a microtransducer. The data are resolved into erosion power and acoustic power. The former is defined in terms of the power applied to the eroded material to cause the observed pitting and volume loss. The ratio between these power quantities is termed the cavitation erosion efficiency [eta] incav and is found to be essentially constant for the range of tests, being approximately 1.4 x 10-6. The acoustic power which is easily measured can then be used to estimate the eventual material volume erosion rates, i.e. the mean depth of penetration (MDPR), with much greater accuracy than is otherwise possible. The MDPR is measured directly from the weight loss and is calculated from individual pit counts on damaged surfaces. The effects of the degree of cavitation (the extent of the cavitation cloud or the cavitation number) and the throat velocity on the MDPR is examined. An overall velocity damage exponent of n = 4.75 is found.