Modeling of Hydroacoustic Noise from Marine Propellers with Tip Vortex Cavitation

TL;DR

This study models the hydroacoustic noise generated by marine propellers during cavitation using advanced simulation techniques, revealing how cavitation structures amplify underwater noise across frequencies and directions.

Contribution

It introduces a comprehensive modeling framework combining LES, cavitation, and acoustic analogies to analyze cavitating propeller noise, validated against experimental data.

Findings

Cavitation increases low-frequency tonal peaks and broadband noise in the spectrum.

Tip vortex cavitation significantly enhances hydroacoustic energy, especially downstream.

Sound pressure levels can increase by up to 20 dB due to cavitation effects.

Abstract

The present work aims to study the cavitating turbulent flow of a full-scale marine propeller and explore the physical mechanism underpinning the underwater radiated noise. We employ the standard dynamic large eddy simulation for the turbulent wake flow and the Schnerr-Sauer cavitation model, while the Ffowcs-Williams-Hawkings acoustic analogy is considered for the hydroacoustic modeling. For the current investigation, we consider a well-known Potsdam Propeller Test Case to analyze the turbulent cavitating flow and the associated hydroacoustic emissions. To begin, the modeling framework is validated using the available experimental data, and distinctive double-helical tip vortex cavitation and its qualitative patterns along the vortex trajectory are captured. In comparison to the non-cavitating condition, the pressure distribution on the propeller surface is more disordered for the cavitating condition, which is further reflected by a relatively stronger power of both low-frequency tonal peaks and high-frequency broadband components in the spectrum of thrust generation. Specifically, the generation of cavitation leads to the enhancement of the monopole noise source and the breakdown of cavitation bubbles as well as vortex structures in the turbulent wake. Furthermore, the tonal noise with the frequency corresponding to the harmonics of blade passing frequency is also enhanced. Generally speaking, the generation of cavitation structures enhances the hydroacoustics energy of URN at all orientations, especially in the downstream direction with sound pressure level increasing up to 20 dB.