Numerical investigation of cavitation induced noise and noise reduction mechanism for the leading-edge protuberances

Applied Ocean Research, Journal Year: 2024, Volume and Issue: 154, P. 104361 - 104361

Published: Dec. 5, 2024

Language: Английский

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Numerical study on cavitation–vortex–noise correlation mechanism and dynamic mode decomposition of a hydrofoil

Physics of Fluids, Journal Year: 2022, Volume and Issue: 34(12)

Published: Nov. 16, 2022

The large eddy simulation model coupled with the modified Schnerr–Sauer cavitation has been used to numerically simulate unsteady and noncavitation flow of three-dimensional NACA66 (National Advisory Committee for Aeronautics) hydrofoil under different operating conditions. results show that magnitude number plays a decisive role in quasiperiodic phenomenon. 1.25 is as typical working condition analysis. Using Ffowcs Williams–Hawkings acoustic analogy approach accompanied by vorticity transport equation splitting, growth shedding also lead vortex structure. cavitation–vortex interaction mainly influenced stretching term dilatation amplitude them are larger than 500. baroclinic torque may be responsible generating during cloud collapse lower about 200. cavity volume acceleration main influencing factor low-frequency pressure fluctuation around cavitating hydrofoil. Moreover, surface-pressure data collected dynamic mode decomposition locate surface noise sources. alternate high low regions overlap highly transformation regions. fluctuations reason generation periodic source on surface. corresponding frequencies each order linearly correlated frequency 5.70 Hz. Combined multiple comparisons, it can inferred suction effect will generate waves starting from upstream moving downstream.

Language: Английский

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Spatial-temporal evolution of tip leakage cavitation with double-hump in a mixed flow pump with tip clearance

Physics of Fluids, Journal Year: 2023, Volume and Issue: 35(4)

Published: April 1, 2023

Tip clearance in pump induces tip leakage vortex (TLV), which interacts with the main flow and leads to instability of pattern decrease performance. In this work, a closed-loop experimental rig high-speed observation for mixed is established, numerical simulation on cavitation conducted validation. A new double-hump first observed pump. Results show that primary develops from linear banded and, finally, pattern. The spatial–temporal evolution can be classified into four stages: incepting stage, growing merging propagating stage. inception front hump found correspond periodic specific passage vortex-tip (PV-TLV) pair. Affected by propagation high-pressure area at outlet, PV wanders downstream passage, greatly affects intensity flow. away motion brings stronger results intensified TLV lower core pressure. As result, incepts, grows, travels downstream. Finally, it merges rear together propagates passage.

Language: Английский

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On the effects of hybrid surface wettability on the structure of cavitating flow using implicit large eddy simulation

Journal of the Taiwan Institute of Chemical Engineers, Journal Year: 2023, Volume and Issue: 148, P. 104828 - 104828

Published: March 22, 2023

Language: Английский

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Tip vortex cavitation suppression and parametric study of an elliptical hydrofoil by water injection

Physics of Fluids, Journal Year: 2023, Volume and Issue: 35(1)

Published: Jan. 1, 2023

Tip vortex cavitation (TVC) affects hydrodynamic performance and can cause drastic vibration noise; therefore, it is crucial to predict the evolution of TVC, understand its generation mechanism, determine methods control it. In this work, a large eddy simulation was performed resolve unsteady turbulence, Schnerr–Sauer model used capture transient cavitating flow. Both wetted conditions were in first step validate numerical methods. The mechanism TVC development interactions between tip also revealed. Next, active by water injection suppress side top circumstances explored compared. Parametric studies conducted for condition changing velocity angle. results showed that both injections had remarkable effects on control. Flow field analysis demonstrated flow affected local magnitude direction incident vortex, thus reducing strength TVC. For condition, directly influenced incepted structures vortex. As result, deeply deformed decreased intensity Furthermore, increasing or component cross-streamwise could effectively increase inhibition rate.

Language: Английский

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Effect of water injection on tip leakage vortex cavitation for a NACA0009 hydrofoil with medium clearance

Ocean Engineering, Journal Year: 2025, Volume and Issue: 320, P. 120349 - 120349

Published: Jan. 13, 2025

Language: Английский

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Surface cavitation flow characterization of jet hydrofoils based on vortex identification method

Physics of Fluids, Journal Year: 2022, Volume and Issue: 35(1)

Published: Dec. 16, 2022

The vortex structure is a typically coherent structure. influence of hydrofoil jets with different chordal positions on the in flow field investigated to improve suppression mechanism cavitation by jet hydrofoils. investigation based identification method and position best effect large-scale surface explored. In addition, dynamics states are analyzed means transport equations optimal chordwise position. results show that U-shaped main morphology bubble shedding; form shedding surface; compared original other positions, can be suppressed better when located at 0.6c; dominant vorticity terms various stages. primary stage, dilatation term dominant. contrast, during development, maturation, phases, stretching dominates, reducing pressure gradient suppressing strength return jet.

Language: Английский

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Experimental and numerical study on the effects of sweep angle on cavitation around a wedge-section hydrofoil

Physics of Fluids, Journal Year: 2023, Volume and Issue: 35(7)

Published: July 1, 2023

The influence of sweep angles on cavitation characteristics and mechanisms a wedge-section hydrofoil is investigated experimentally numerically. Four hydrofoils with 0° (straight), 30°, 45°, 60° are considered across range numbers from 2.00 to 0.48 angle attack (AOA) 0°, 5°, 10°, 15°. Two high-speed cameras used visualize the flow in tunnel. numerical simulation conducted using unsteady Reynolds-averaged Navier–Stokes equations through OpenFOAM. At an AOA vortex first appears wake region all models at number 0.98. However, higher values 10° 15°, tip-vortex (TVC) begins for straight foil, this followed by sheet cavitation. In contrast, swept foil does not succumb TVC. Instead, as increases, develops into root leading-edge (LEVC). inclination LEVC leading edge observed be between 6° depending angle, it independent AOA. changes eddy shedding two trailing-edge vortices increases. reduces average cavity volume more than 45% compared foil. lift coefficient increases generated reaches maximum value 0.6 when covers suction side before dropping sharply extends region. there only minor deterioration swept-angle occurs. drag forms both foils. lower that These findings offer valuable insight design optimization foils various applications where affects their performance stability.

Language: Английский

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Suppression of hydrofoil unsteady cavitation by periodic jets based on fish gill respiration

Ocean Engineering, Journal Year: 2023, Volume and Issue: 293, P. 116584 - 116584

Published: Dec. 27, 2023

Language: Английский

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Loading noise induced by cavitating flow and its simplified model prediction

Ocean Engineering, Journal Year: 2023, Volume and Issue: 280, P. 114584 - 114584

Published: May 2, 2023

Language: Английский

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