Mechanism of propagation direction of rotating cavitations in a cascade

The propagation mechanism of rotating cavitations, especially that of supersynchronous rotating cavitation, is still unclear. The direction of propagation of supersynchronous rotating cavitation is in the direction of rotation of an impeller, which is opposite of the direction of rotating stall in general pumps and fans. Also, neither the mechanism of the order of appearance of rotating cavitations (supersynchronous, synchronous, and subsynchronous propagation) nor the mechanism of the discontinuity of the propagation speed during the transition between different types of rotating cavitations has been determined thus far. The present study indicates that they can be explained by the existence of latent rotating stall and a specific feature of cavitation: A decrease in the break-off frequency of a cavitation according to its development.