Numerical method to determine the cavitation inception speed of a submarine propeller based on the noise obtained from bubble dynamics

Abstract

Cavitation is accompanied by increased hull vibrations, reduced propulsion performance, and increased radiated noise. This can be particularly fatal for warships and submarines. Hence, navies worldwide introduced and managed a propeller performance index called cavitation inception speed (CIS). Among the many types of propeller cavitation, the first to occur is tip vortex cavitation (TVC). In this paper, the CIS decision procedure of TVC is presented via numerical analysis in terms of noise, which is the most prominent characteristic of cavitation inception. For the CIS decision, the cavitation noise from the propeller is obtained from bubble dynamics. Cavitation is simulated with cavitation nuclei, and the input data for nuclei is obtained from computational fluid dynamics (CFD) simulations. The noise from each nucleus was modeled with a monopole assumption. Additional impulse noise due to the bubble's implosion is used as the basis for the CIS decision. The usefulness of the proposed procedure is demonstrated by applying it to three propeller geometries with different skew and rake angles. Additionally, various aspects, such as propeller stern vortex and added mass, are analyzed; the results are consistent with the CIS simulation results for each propeller.