Acoustic Field Radiation Prediction and Verification of Underwater Vehicles under a Free Surface

Article Engineering, Marine

Visualization of Underwater Radiated Noise in the Near- and Far-Field of a Propeller-Hull Configuration Using CFD Simulation Results

Julian Kimmerl et al.

Summary: Underwater radiated noise is a significant issue for marine ecosystem conservation due to its contribution as part of anthropogenic emissions. To accurately identify relevant noise sources associated with ships, determining the local origins of acoustic emissions is crucial. Visual post-processing support is necessary in engineering applications to assess the impact on structures and create a comprehensive understanding of the noise field. This can be achieved through various methods, such as analyzing pressure pulses on boundary surfaces or evaluating volumetric information like Proudman acoustic sources or the Lighthill stress tensor in CFD simulations.

JOURNAL OF MARINE SCIENCE AND ENGINEERING (2023)

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Article Engineering, Marine

A study on the propeller open water performance due to immersion depth and regular wave

Myeong-Jin Eom et al.

Summary: This study utilizes computational fluid dynamics to assess the impact of different immersion depths on propeller open water (POW) performance in waves, and compares it with the performance characteristics in calm water. Results indicate that the variation of propeller performance due to changes in wave elevation is similar to the effect of immersion depth changes in calm water. Additionally, the impact of water particle velocity changes based on wave phase is analogous to the variation in propeller performance due to changes in advance ratio in calm water.

OCEAN ENGINEERING (2021)

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Article Mechanics

Numerical simulation of the cavitating noise of contra-rotating propellers based on detached eddy simulation and the Ffowcs Williams-Hawkings acoustics equation

Jian Hu et al.

Summary: Contra-rotating propellers (CRPs) are widely used in underwater vessels for their stability, efficiency, and torque distribution, but high rotational speeds lead to cavitation and high levels of cavitation noise. The noise sound-pressure levels generally decrease with increasing frequency, but when cavitation is present, the noise levels become significantly higher.

PHYSICS OF FLUIDS (2021)

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Article Mechanics

Full-scale simulation of self-propulsion for a free-running submarine

Liwei Liu et al.

Summary: This study uses computational fluid dynamics (CFD) simulations to predict the self-propulsion performance of a full-scale submarine propelled by a high-skew propeller. Model- and full-scale simulations are conducted and compared, showing consistent results with minor discrepancies after adequate corrections. Discussions are provided on the differences between model- and full-scale self-propulsion results, including propeller performance, pressure distribution, boundary layer, and wake flow.

PHYSICS OF FLUIDS (2021)

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Article Mechanics

Scaling properties of the Ffowcs-Williams and Hawkings equation for complex acoustic source close to a free surface

M. Cianferra et al.

Summary: In this study, a scaling analysis of the terms composing the Ffowcs-Williams and Hawkings (FWH) equation was performed, considering perfect and imperfect similarity, as well as the effects of laboratory-scale data on full-scale predictions. The influence of scaling analysis in a hydrodynamic example and the interference effects of a free surface were investigated. The research also found errors in full-scale acoustic pressure predictions when using model-scale data, particularly due to imperfect similarity and the absence of a free surface.

JOURNAL OF FLUID MECHANICS (2021)

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Article Engineering, Marine

A method for predicting propeller performance considering ship motion in regular waves

Myeong-Jin Eom et al.

Summary: This study investigated the influence of immersion depth and tilt angle on propeller performance in calm water and waves through numerical simulations and model tests, developing a prediction method. The results could be considered useful for predicting a ship's performance in waves.

OCEAN ENGINEERING (2021)

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Article Mechanics

Influence of jet flow on the hydrodynamic and noise performance of propeller

Hang Guo et al.

Summary: This study investigated the effects of jet flow on the hydrodynamic performance and noise characteristics of underwater vehicles and propellers using numerical simulation methods. The results showed that a triangular jet can significantly improve the circumferential distribution uniformity of the wake field at the propeller plane and reduce the dynamic loads on the propeller blades.

PHYSICS OF FLUIDS (2021)

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Article Engineering, Marine