Mechanism of Propagation Direction of Rotating Cavitations in a Cascade

摘要

The propagationmechanismof rotating cavitations, especially that of supersynchronous rotating cavitation, is stillnunclear. The direction of propagation of supersynchronous rotating cavitation is in the direction of rotation of annimpeller,which is opposite of the direction of rotating stall in general pumps and fans.Also, neither themechanismofnthe order of appearance of rotating cavitations (supersynchronous, synchronous, and subsynchronous propagation)nnor the mechanism of the discontinuity of the propagation speed during the transition between different types ofnrotating cavitations has been determined thus far. The present study indicates that they can be explained by thenexistence of latent rotating stall and a specific feature of cavitation: a decrease in the break-off frequency of ancavitation according to its development.