Cavitation Instabilities in Inducers

Experimental observations of various kinds of cavitation instabilities are presented. Typical cavitation instabilities occur in the range of cavitation number where the inducer head is not affected by cavitation. This type of cavitation instability is caused by the cavity volume increase due to the increase of incidence angle and is treated in section 1. Another type of cavitation instability is caused by the positive slope of the pressure performance curve due to the blockage effect of cavitation. This type of cavitation instability is treated in section 2. Stability analyses of 1- and 2-dimensional cavitating flow predict various modes of cavitation instabilities. Usually only cavitation surge and forward rotating cavitation are observed. Other modes of cavitation instabilities such as backward rotating cavitation, higher order modes of cavitation surge and rotating cavitation are observed only under limited conditions. Those modes of cavitation instabilities are presented in section.