Session: 06-15-01 Unsteady Hydrodynamics, Vibrations, Acoustics and Propulsion

Submission Number: 156118

LES Analysis of Vortex-Vortex Interaction and Associated Acoustic Signatures 

The rising levels of underwater ambient noise due to shipping have attracted attentions of national and international bodies such as the Vancouver Ports in Canada and the International Maritime Organization (IMO), both of which aim to minimize the underwater radiated noise and reduce the negative impacts to marine creatures. Reconnection and breakdown of coherent vortex structures in propellers' wake can produce significant pressure fluctuations, intensifying turbulent energy and leading to a distinct noise signature. A highly intensified noise not only contributes to noise pollution that can disturb marine life but also brings negative impacts on ship operation. Relatively limited studies have investigated the specific acoustic signatures resulting from this vortex-vortex interaction. This study aims to understand these interactions and their associated acoustic signatures across a wide range of vortex Reynolds numbers, from moderate to high. The primary objective is to understand the dynamics of co-rotating and counter-rotating parallel vortex pairings. Additionally, the study examines the corresponding far-field acoustic signatures generated by these interactions. These are conducted using Computational Fluid Dynamics methods, where Large Eddy Simulation (LES) in combination with the Ffowcs Williams-Hawkings acoustic analogy are used to solve the hydrodynamic flow field and propagation of associated noises to the far field. The unique acoustic signatures and hydrodynamic characteristics obtained from this investigation provide an alternative perspective for understanding vortex acoustics.

Presenting Author: Zehao Sun Newcastle University

Presenting Author Biography: Zehao Sun graduated with a BEng in Naval Architecture and Marine Engineering from the Department of Naval Architecture, Ocean, and Marine Engineering at the University of Strathclyde. In 2023, he began his PhD at Newcastle University, where his research focuses on understanding vortex-vortex interactions and their associated acoustic signatures in propeller wakes, as well as mitigating propeller-induced underwater radiated noise through bio-inspired solutions. His research combines computational fluid dynamics (CFD) and experimental testing in the Emerson Cavitation Tunnel.