Theoretical Analysis of Rotating Cavitation in Inducers

Abstract

Rotating cavitation is analysed by means of an actuator disk method. Quasi-steady pressure performance, mass flow gain factor and cavitation compliance are taken into account. Three types of destabilizing modes are observed : rotating cavitation propagating faster than the impeller speed, rotating cavitation propagating opposite to the impeller rotational direction, and rotating stall propagating slower than the impeller speed. It is shown that both of the rotating cavitations are caused by the positive mass flow gain factor, while rotating stall is by the positive slope of the pressure performance. Stability and propagation velocity maps are given for the two types of rotating cavitations in the mass flow gain factor-cavitation compliance plane. The results of the analysis and the experimentally observed rotating cavitations are discussed. © 1992, The Japan Society of Mechanical Engineers. All rights reserved.