Towards Better Quantification of Underwater Radiated Noise: A Population Balance Model for Cavitating Flows and Noise

Background
The project focuses on the growing challenge of underwater radiated noise (URN) and its negative impact on the marine environment, especially marine life. The primary source of noise is ships and their propeller blades, where cavitation occurs. To tackle ship noise, it is crucial to accurately simulate propeller cavitation and accurately predict the noise radiation. There is significant motivation to improve propeller design to minimise noise, but this requires more advanced simulation tools. The purpose of this project is to develop a computational tool based on computational fluid dynamics for cavitation and noise prediction, for the direct benefit of propeller and hull designers in both industry and research.

Project
Cavitation is typically modelled using Computational Fluid Dynamics (CFD), but current methods reach their limitations at small scales where the effects are not well understood. The project will introduce a new approach based on population-balance equations to handle these sub-grid interactions and thus improve noise predictions from cavitation. This model will be integrated into an open-source CFD software and then coupled with an acoustic radiation model developed at the Technical University of Hamburg (TUHH). Experimental data from tests with stationary hydrofoils and rotating propellers in a cavitation tunnel will be used to validate and fine-tune the model. Thus, the model will be ready to simulate both cavitation and noise.

Expected results
The strategic value for Danish Shipping lies in the opportunity to develop quieter propeller designs and thereby fulfil IMO guidelines and other regulatory standards.

1. Creation and validation of an accurate CFD model to simulate cavitation on macroscopic geometries such as hull and propeller.
2. Integration of developed cavitation model with the acoustic radiation model from TUHH and validation based on experimental data.
3. Analysing the relationship between noise, rotational speed and propulsion for a full-scale propeller.
4. Establishment of strategic research collaboration with the Institute for Fluid Dynamics and Ship Theory at TUHH.