Modal analysis of propeller wakes under different loading conditions

Wang, Lianzhou; Liu, Xinyu; Wang, Nian; Li, Mijian

doi:10.1063/5.0096307

Cited by 29 publications

(6 citation statements)

References 45 publications

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“…(DDES), and improved DDES (IDDES) have been very popular in propeller wake studies [21][22][23][24][25][26][27][28][29][30][31]. Based on the literature survey presented above, it is evident that there are limited LES studies on propeller wakes under various loading conditions.…”

Section: Research Modelmentioning

confidence: 99%

“…Furthermore, CFD methods inevitably entail numerical dissipation, which introduces non-physical factors into the results. Recently, hybrid LES/RANS models such as DES, delayed DES (DDES), and improved DDES (IDDES) have been very popular in propeller wake studies [21][22][23][24][25][26][27][28][29][30][31]. Based on the literature survey presented above, it is evident that there are limited LES studies on propeller wakes under various loading conditions.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Analysis of Propeller Wake Evolution under Different Advance Coefficients

Yu²,

Li³

et al. 2023

JMSE

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Propeller wake fields in an open-water configuration were compared between two loading circumstances using large-eddy simulation (LES) with a computational domain of 48 million grids and an overset mesh technique. To validate the results of the numerical simulation, available experimental data are compared, which indicates that the grid systems are suitable for the present study. The results indicate that the present LES simulations describe the inertial frequency range well for both high and low-loading conditions. Under high-loading conditions, the interlaced spirals and secondary vortices that connect adjacent tip vortices amplify the effects of mutual inductance, ultimately triggering the breakdown of the propeller wake systems. At a great distance from the propeller, the vortex system loses all coherence and turns into a collection of smaller vortices that are equally scattered across the wake. In contrast, under light-loading conditions, the wake vortex system exhibits strong coherence and has a relatively simple topology. The elliptic instability and pairing processes are only observed at a far distance from the propeller. The convection velocity transferring tip vortices downstream is larger under the light-loading condition, which leads to the larger pitch of the helicoidal vortices. The larger pitch weakens the mutual inductance or interaction effects among tip vortices, which delays the instability behaviors of the whole vortex system. The results and implications of this study serve as a guide for the development and improvement of next-generation propellers that function optimally when operating behind aquaculture vessels.

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Section: Research Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Propeller Wake Evolution under Different Advance Coefficients

Yu²,

Li³

et al. 2023

JMSE

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“…(2022), Wang et al. (2021 a , 2022 b , c ) and Wang, Luo & Li (2022 e ). In these studies, computational grids consisting of points are utilized, which is a significant step forward, in comparison with the typical resolutions adopted to conduct RANS computations, usually relying on meshes consisting of a few million points.…”

Section: Introductionmentioning

confidence: 98%

“…However, the RANS approach and its limitations are retained in the vicinity of the surface of the bodies immersed within the flow. Examples of this technique for the numerical prediction of the wake of marine propellers can be found in Muscari, Di Mascio & Verzicco (2013), Gong et al (2018Gong et al ( , 2020, Guilmineau et al (2018), Zhang & Jaiman (2019), Sun et al (2020), Shi et al (2022), Wang et al (2021aWang et al ( , 2022b and Wang, Luo & Li (2022e). In these studies, computational grids consisting of O(10 7 ) points are utilized, which is a significant step forward, in comparison with the typical resolutions adopted to conduct RANS computations, usually relying on meshes consisting of a few million points.…”

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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“…To date, most studies on contra-rotating propellers are focused on the analysis of the global performance for improved efficiency and design, [1][2][3][4][5][6][7][8][9][10][11] while little is known about their wake features. While the latter are already especially complex in the case of propellers working alone, [12][13][14][15][16][17][18][19][20][21][22][23] the analysis of their physics becomes even more problematic, when two contra-rotating propellers work together. Therefore, a very limited number of studies tackle the problem of the wake flow of contra-rotating propellers, due to the challenge they represent to both experimental and numerical methodologies.…”

Section: Introductionmentioning

confidence: 99%

Interaction between the helical vortices shed by contra-rotating propellers

Posa,

Capone,

Alves Pereira

et al. 2024

Physics of Fluids

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Large eddy simulation is adopted to analyze the interaction between the tip vortices shed by two contra-rotating propellers, by using a computational grid consisting of 4.6 × 109 points. Despite the complexity of the wake topology, the results of the computations show an excellent agreement with the measurements from an earlier experimental study on the same system. The interaction between the tip vortices shed by the two propellers produces vortex rings. Each of them consists of six helical sides, which are connected by U-shaped vortex lobes. The three upstream lobes of each vortex ring move to outer radial coordinates, as a result of their shear with the downstream lobes of the upstream vortex ring. In contrast, the downstream U-shaped lobes move to inner radial coordinates, as a result of their shear with the upstream lobes of the downstream vortex ring. This interaction results in an overall expansion of the wake of the contra-rotating propellers. The regions of shear between the U-shaped lobes of consecutive vortex rings are the areas of the largest turbulent stresses, which achieve higher levels than those produced in the wake of the two front and rear propellers working alone. This complex flow physics also triggers a faster instability of the wake system, breaking its coherence at more upstream coordinates, in comparison with the isolated propellers.

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Modal analysis of propeller wakes under different loading conditions

Cited by 29 publications

References 45 publications

Numerical Analysis of Propeller Wake Evolution under Different Advance Coefficients

Numerical Analysis of Propeller Wake Evolution under Different Advance Coefficients

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

Interaction between the helical vortices shed by contra-rotating propellers

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