A Theoretical Analysis of Rotating Cavitation in Inducers

Rotating cavitation was analyzed using an actuator disk method. Quasi-steady pressure performance of the impeller, mass flow gain factor, and cavitation compliance of the cavity were taken into account. Three types of destabilizing modes were predicted: rotating cavitation propagating faster than the rotational speed of the impeller, rotating cavitation propagating in the direction opposite that of the impeller, and rotating stall propagating slower than the rotational speed of the impeller. It was shown that both types of rotating cavitation were caused by the positive mass flow gain factor, while the rotating stall was caused by the positive slope of the pressure performance. Stability and propagation velocity maps are presented for the two types of rotating cavitation in the mass flow gain factor-cavitation compliance plane. The correlation between theoretical results and experimental observations is discussed.