![]() This paper investigates the two-dimensional SSL of stationary targets using only three receivers. This kind of localization method is carried out in a passive way, without the emission of any signals, and cannot be detected easily. The sound source localization (SSL) system is one of the main approaches for detecting targets. They develop instability at a faster rate, compared with the hub vortex, triggering the process of energy cascade towards higher frequencies and contributing in this way to broadband noise. Therefore, the acoustic signature of the propeller is mainly tonal in the near field only, due to the thickness and loading components of noise from the surface of the propeller and the periodic perturbation caused by its tip vortices. In particular, this growth affects frequencies lower than the blade frequency. While the linear terms experience a decay moving downstream, the nonlinear terms grow in the near wake, as a result of the development of wake instability. Results demonstrate that the nonlinear terms of the Ffowcs-Williams and Hawkings equation quickly become dominant moving away from the propeller along the direction of its wake development. The acoustic analogy is adopted to characterise the signature of a seven-bladed submarine propeller, relying on a high-fidelity large-eddy simulation, performed on a computational grid consisting of 840 million points. In addition, the structure-borne noise under distributed pulsation pressure is mainly radiated from the conical end caps and the stern, while the flow noise is mainly radiated from the cylindrical hull. For the calculation conditions of low-speed navigation, the sound pressure level (SPL) of the structure-borne noise is higher than that of the flow noise. In the studied frequency range, the spectrum characteristics of the structure-borne noise of the submarine are mainly contributed by the longitudinal mode of the shafting system, in-phase mode of the rotor blades, and the characteristic peaks of the pulsation pressure. The spectrum characteristics of the flow noise are similar to those of the pulsation pressure, with peaks at BPF and its multiples. Finally, the structure-borne noise of coupled pump-jet– shafting– SUBOFF system under distributed pulsation pressure is predicted by coupled finite element method (FEM) and BEM. Then, the pulsation pressure on the pump-jet and the submarine are obtained by the verified CFD model, which is transferred to obtain the flow noise. Firstly, the numerical approaches of computational fluid dynamics (CFD) employed to predict the pulsation pressure and the boundary element method (BEM) employed to calculate the flow noise are verified. This study presents the characteristics of the flow noise of a fully appended SUBOFF propelled by a pump-jet and the comparison with the structure-borne noise. The paper also includes the details of the bodies and discusses further improvement of the methodology applied. This paper reports the results of the study. Flow around the propeller is solved with a commercial CFD software using Unsteady Reynolds Averaged Navier–Stokes (URANS), while hydro-acoustic analysis is performed using a model based on Ffowcs-Williams and Hawkings equation. ![]() Propeller noise has been investigated numerically for the INSEAN E1619 submarine propeller in open water, behind a generic DARPA suboff submarine and within imposed wake cases at non-cavitating conditions due to their deeply submerged operations. In this respect, the main objective of this study is to calculate propeller radiated noise numerically. Therefore, it is important to predict and control the underwater noise characteristics of propellers. The propeller is one of the main sources of underwater noise generated by ships. ![]() this has already been an issue because of their operational requirements. However for special ships, such as naval surface vessels, fishing vessels, submarines, etc. Ships with low noise characteristics will be a must in the near future for almost all ship types. International Maritime Organisation (IMO) and other bodies have been trying to set-up guidelines and regulations to reduce/limit noise levels at sea which influence marine life in particular marine mammals and certain fish types.
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