Hydro-acoustic optimization of propellers: A review of design methods

Applied Ocean Research, Journal Year: 2024, Volume and Issue: 151, P. 104158 - 104158

Published: Aug. 17, 2024

In recent years, the escalation of anthropogenic noise within marine environments has become a pressing ecological concern. Despite proliferation guidelines aimed at mitigating this issue, their adoption remains non-compulsory. The International Maritime Organization (IMO) advocates for reduction through refinement propeller design and heightened research to curtail acoustic emissions, ensuring that such measures do not compromise propulsive efficiency. This review delves into array strategies devised attenuate pollution. It scrutinizes methodologies employed evaluate hydroacoustic attributes propellers, including experimental computational approaches. Furthermore, it summarizes techniques in multiobjective optimization which involves balancing maximization efficiency against minimization emission. findings highlight necessity comprehensive, interdisciplinary approach encompassing cavitation experiments advanced numerical simulations. field optimization, traditional reliance on genetic algorithms is giving way neural networks surrogate models derived from fluid dynamics data, particularly when addressing complex, nonlinear phenomena as hydro-acoustics cavitation.

Language: Английский

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Fast and accurate prediction of flow in multi-row cascade based on combined neural networks

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(1)

Published: Jan. 1, 2025

This paper proposes a fast and accurate method for predicting multi-row cascade flow based on framework of combined neural networks. The primary idea this is to decompose the whole-annulus into different types sub-regions, prediction surrogate models networks are constructed these sub-regions in rectangular computational domain by applying coordinate transformation technique. each sub-region then combined, continuity at interfaces among used iteratively compute cascade. main advantages proposed include reduced dataset generation cost network training through spatial decomposition, as well ability achieve combining sub-regions. test case two-dimensional stator-rotor interaction indicates that time developed approximately 5% required numerical simulation, with over 99% nodes field exhibiting normalized absolute error less than 0.05. approach can be further extended three-dimensional multi-stage turbomachinery.

Language: Английский

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On energy conversion mechanism of a marine submerged waterjet

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(3)

Published: March 1, 2025

The submerged waterjet (SWJ) is a novel marine propulsor for surface ships, which shows remarkable energy performances in mixed-use profile. Less research has been done to reveal the mechanisms of its distinguished and propulsion performances. Based on flux balance theory, this paper proposes method analysis conversion process SWJ system, where link established between performance quantitative evolution components occurring both internal external flows through control volume system. detailed investigation indicates that various interactions, among rotor, stator duct, exhibit different impacts enhancing overall duct majorly changes working environment rotor from flow operation ones. After adding shaft power increases sharply, due increased pressure distribution domain. Afterward, system can experience stronger work into axial kinetic flux, enables have greater potential generate larger thrust. As post-stator, it improves open water efficiency dominantly enhancement hydraulic efficiency. In detail, positive impact post-stator mainly achieved by increasing proportion promoting transversal ones pump inner For around downstream also plays significant role improving hub vortex as well stability tip leakage vortex. A more stable field one important prerequisites reducing vibration noise Another enhance generating additional thrust guide vanes reduce drag at same time.

Language: Английский

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Comparative study of tonal noise prediction methods for stator-rotor interaction

Ocean Engineering, Journal Year: 2025, Volume and Issue: 335, P. 121706 - 121706

Published: June 3, 2025

Language: Английский

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Flow characteristics analysis of an ultrathin forward-curved multi-blade centrifugal fan

Engineering Applications of Computational Fluid Mechanics, Journal Year: 2024, Volume and Issue: 19(1)

Published: Dec. 12, 2024

The ultrathin centrifugal fan, widely utilised in compact electronic devices such as laptops, is characterised by numerous forward-curved blades that generate high static pressure and flow rates. Despite its widespread application, the dynamics of fans remain insufficiently explored. In large-scale turbomachinery, boundary layer thickness typically negligible, with separation being primary contributor to losses. However, loss mechanisms are not yet well understood. This study addresses these gaps investigating entropy production associated various processes, decomposing generation into components related molecular viscosity eddy viscosity. Large Eddy Simulation (LES) employed analyze turbulent characteristics fans. findings indicate thickness, constituting approximately 10% volute height, substantial. Viscous dissipation within generates 2.85×10−4W/K entropy, whereas contributes 1.16×10−5W/K, underscoring significant impact on fan's operational efficiency. To further investigate turbulence characteristics, hot-wire anemometry measurements were conducted obtain energy spectrum. Moreover, scale fluctuations derived from simulation results analyzed frequency domain, revealing low-frequency linked blade surfaces, while high-frequency shell. insights gained this field analysis can inform design more efficient quieter cooling

Language: Английский

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Entropy transport for quasi-one-dimensional flow

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(7)

Published: July 1, 2024

The study of entropy in the context quasi-one-dimensional flow is expanded this work. Specifically, a new transport equation derived and integrated into closed-form algebraic expression for change. derivation identifies respective components change valid flows with an arbitrary combination area change, heat transfer, friction. irreversibility identified found to be composed frictional dissipation, irreversible work term that results from restriction flows. each component first validated using several canonical (i.e., isentropic, Fanno, Rayleigh, normal shock). A unique production mechanism producing (e.g., Two additional cases, sudden expansion contraction, are then considered show sole mechanism. Finally, simultaneous friction transfer examined, overall decomposed contributions dissipation terms. In all net newly expressions agrees known solutions within numerical precision.

Language: Английский

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