A NONLINEAR CALCULATION OF ROTATING CAVITATION IN INDUCERS

In the previous linear analysis (Tsujimoto et al., 1993) it was found that there cart be a backward rotating cavitation as well as a forward mode which rotates faster than impeller. Although some shaft vibratio n has been observed, which might be caused by the backward mode, exper imental evidence has been obtained only for the forward mode, The purp ose of the present study is to find out the factors which determine th e amplitude of each mode of rotating cavitation by taking into account several nonlinearities. A time marching nonlinear 2-D flow analysis w as carried out for this purpose. It was found that the increase of cav itation compliance at lower inlet pressure can be a factor which limit s the amplitude. The mode selectivity is mainly dependent on the stabi lity limit obtained by a linear analysis for which the phase delay of cavity has a most important effect.