Propeller Tip Vortex Cavitation Noise Inception

Abstract

The recent concern for reducing ship noise has resulted in the necessity of treating propeller cavitation noise. In this paper a review of the work on tip vortex cavitation is used to begin a discussion of propeller hub and tip vortex cavitation noise. Model propeller noise measurements are used to characterize hub and tip vortex cavitation noise. The tip vortex cavitation (TVC) noise envelope is introduced to show how the inception of propeller TVC noise is delayed using propellers with larger pitch-diameter ratios. The propeller TVC noise envelopes are shown to collapse into an equivalent hydrofoil TVC noise envelope. The theoretical simulation of the hydrofoil TVC noise envelope is then outlined. The results of computer calculations for 1/4 SRI hydrofoil with a NACA 4412 section are presented to show the role of the vortex circulation, vortex radius, nuclei size, and cavitation tunnel background noise on tip vortex cavitation noise inception.