A Numerical Investigation of a Winglet-Propeller Using an LES Model

Zhu, Wencai; Gao, Hongtao

doi:10.3390/jmse7100333

Cited by 23 publications

(9 citation statements)

References 37 publications

(59 reference statements)

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“…In addition, for motor blades, inspired by bionics, 160 Zhu and Gao utilized a winged propeller to suppress the generation of tip vortex cavitation (TVC). 45 Also, the simulation results showed that the winglet propeller significantly weakened the strength of the blade tip vortex wake and had a significant effect. Moreover, inspired by the shark skin effect, Büttner and Schulz prepared a riblet structure surface with a fluid wall friction reduction of 4.9%.…”

Section: Applicationsmentioning

confidence: 95%

Thriving artificial underwater drag-reduction materials inspired from aquatic animals: progresses and challenges

et al. 2021

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Section: Applicationsmentioning

confidence: 95%

Thriving artificial underwater drag-reduction materials inspired from aquatic animals: progresses and challenges

et al. 2021

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“…However, the LES studies currently available in the literature typically rely on computational grids consisting of points, similar to those for the DES computations reported above, and are usually targeted at analysing the process of instability of the wake system of marine propellers and the cavitation phenomena occurring within the large coherent structures they shed (Liefvendahl 2010; Liefvendahl, Felli & Troëng 2010; Asnaghi, Svennberg & Bensow 2018 a , b , 2020 a ; Hu et al. 2019 a ; Zhu & Gao 2019; Ahmed, Croaker & Doolan 2020; Asnaghi et al. 2020 b ; Long et al.…”

Section: Introductionmentioning

confidence: 99%

Anisotropy of turbulence at the core of the tip and hub vortices shed by a marine propeller

Posa

2023

J. Fluid Mech.

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Large-eddy simulation on a grid consisting of 5 billion points was utilized to study the properties of turbulence at the core of the tip and hub vortices shed by a marine propeller across working conditions. Turbulence at the core of the tip vortices was found to be initially isotropic, moving towards a ‘cigar-shaped’ axisymmetric state as instability grows, dominated by turbulent fluctuations of the velocity component directed in the radial direction of the cylindrical reference frame centred at the wake axis. The break-up of the coherence of the tip vortices is instead characterized by turbulence recovering an isotropic state. This process is accelerated by growing load conditions of the propeller. In contrast, during instability of the hub vortex, turbulence at its core develops a ‘pancake-shaped’ axisymmetric state, dominated by the fluctuations of the radial and azimuthal velocities. However, at higher propeller loads turbulence at the core of the hub vortex keeps close to isotropy, thanks to a faster instability. Within both tip and hub vortices the deviations from Boussinesq's hypothesis were found very significant, providing evidence of the unsuitability of conventional turbulence modelling. At the core of the tip vortices they become especially large at their break-up and for increasing load conditions of the propeller, equivalent to more intense structures. In contrast, at the core of the hub vortex they were verified to be decreasing functions of the propeller load.

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“…This is consistent with the limitations in terms of both grid resolution and computational technique, negatively affecting the simulation of the wake flow and resulting in the quick diffusion of the wake structures. An exception in this field is the work reported by Zhu & Gao (2019). However, they adopted LES on a grid consisting of only 11 million points, similar to those typical of lower-fidelity, RANS computations and not well suited to eddy-resolving simulations.…”

Section: Introductionmentioning

confidence: 99%

The dynamics of the tip vortices shed by a tip-loaded propeller with winglets

Posa

2022

J. Fluid Mech.

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The tip vortices shed by two marine propellers are studied, relying on large-eddy simulation, using a cylindrical grid consisting of 5 billion points. A tip-loaded design, featuring winglets at the tips of its blades, is compared against a conventional one at the design advance coefficient and a model-scale Reynolds number equal to 432 000. The tip-loaded propeller achieves improved performance, but produces also more intense tip vortices. The propeller with winglets actually generates two vortices from the tip of each blade, originating at the edge of each winglet and at the junction between the winglets and the blades. They merge at a short distance downstream, within a diameter from the propeller plane. The helical vortices originating from this merging process experience a slower instability, in comparison with the tip vortices in the wake of the conventional propeller, persisting further downstream, due to the weaker shear with the wakes shed by the following blades. The results of the simulations highlight that splitting the single tip vortex of a conventional propeller into two smaller vortices by means of winglets does not imply necessarily the generation of weaker vortices and lower negative peaks of pressure at their core: the geometry of the winglets needs to be carefully optimized to achieve this target.

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A Numerical Investigation of a Winglet-Propeller Using an LES Model

Cited by 23 publications

References 37 publications

Thriving artificial underwater drag-reduction materials inspired from aquatic animals: progresses and challenges

Thriving artificial underwater drag-reduction materials inspired from aquatic animals: progresses and challenges

Anisotropy of turbulence at the core of the tip and hub vortices shed by a marine propeller

The dynamics of the tip vortices shed by a tip-loaded propeller with winglets

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