Abstract
It is shown that cavitation shocks are recurrent or multiple, the time interval separating them depending primarily on the size of the cavity. Further, it is shown that the abruptness and violence of the shock, the total acoustic energy produced and its frequency distribution are all highly dependent on the size of the residual air bubble around which the cavity collapses. The size of this bubble determines the degree of cushioning of the shock; hence the undesirable characteristics of the shock, as measured by noise production and mechanical destruction, are much diminished as the air-bubble size increases, and the predominant frequency of the noise generated shifts to the lower frequencies. Quantitative relationships for these variables have been obtained as a function of cavity size (or energy content of the blow) and air-bubble size. These are the two significant variables, the properties of the shock are insensitive to the shape of the cavity and the material against which collapse takes place.
