Influence of the wake model on the thrust of oscillating foil

Mantia, M. La; Dabnichki, Peter

doi:10.1016/j.enganabound.2010.09.009

Cited by 22 publications

(3 citation statements)

References 27 publications

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“…Related research has been conducted aiming at the problem. However, the foils were usually modeled in two dimensions or simplified to simple three-dimensional shapes [26][27][28]. Li et al mainly studied the wake topology of forked and unforked fish-like plate with numerical method [10].…”

Section: Introductionmentioning

confidence: 99%

Study on the Hydrodynamic Performance of Typical Underwater Bionic Foils with Spanwise Flexibility

2017

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Bionic foils are usually similar in shape to the locomotive organs of animals living in fluid media, which is helpful in the analysis of the motion mode and hydrodynamic mechanisms of biological prototypes. With the design of underwater vehicles as the research background, bionic foils are adopted as research objects in this paper. A geometric model and a motion model are established depending on the biological prototype. In the model, two typical bionic foils-a NACA foil and a crescent-shaped foil-are chosen as research objects. Simulations of the bionic foils are performed using a numerical method based on computational fluid dynamics software. The hydrodynamic forces acting on the foils and flow field characteristics behind the foils are used to analyze the propulsion performance and hydrodynamic mechanism. Furthermore, a spanwise flexibility model is introduced into the motion model. Next, the hydrodynamic mechanism is further analyzed on the basis of hydrodynamic forces and flow field characteristics with different spanwise flexibility parameters. Finally, an experimental verification platform is designed and built to verify the reliability of the numerical results. Agreement between the experimental and numerical results indicates that the numerical results are reliable and that the analysis of the paper is reasonable.

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Section: Introductionmentioning

confidence: 99%

Study on the Hydrodynamic Performance of Typical Underwater Bionic Foils with Spanwise Flexibility

2017

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“…Previous research has shown that the Strouhal number is the principal parameter governing thrust generation and wake dynamics (Triantafyllou et al, 1991;Ramamurti & Sandberg, 2001). The ideal operating range in terms of thrust and efficiency has been found to be between St = 0.2 to 0.4, with pitch amplitudes between 40 • and 60 • , which has been demonstrated experimentally (Fish, 1998;Anderson et al, 1998;Read et al, 2003;Hover et al, 2004;Schouveiler et al, 2005;Techet, 2007) and computationally (Tuncer & Platzer, 1996;Jones & Platzer, 1997; Young & S. Lai, 2004;Xiao & Liao, 2010;La Mantia & Dabnichki, 2011;Mattheijssens et al, 2013). The effect of heave amplitude has received less attention, but typical values range from h 0 /c = 0.5 to 1.…”

Section: Introductionmentioning

confidence: 73%

Variable thrust and high efficiency propulsion with oscillating foils at high Reynolds numbers

Dave,

Spaulding,

Franck

2019

Preprint

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Bio-inspired oscillatory foil propulsion has the ability to traverse various propulsive modes by dynamically changing the foil's heave and pitch kinematics. This research characterizes the propulsion properties of a symmetric oscillating foil at a high Reynolds number of 10 6 , targeting specialized small to medium surface vessels whose propulsive specifications have a broad range of loads and speeds. An unsteady Reynoldsaveraged Navier-Stokes (URANS) solver with a k-ω SST turbulence model is used to sweep through pitch amplitude and frequency at two heave amplitudes of h 0 /c = 1 and h 0 /c = 2. At h 0 /c = 2, the maximum thrust coefficient is C T = 8.2 due to the large intercepted flow area of the foil, whereas at a decreased Strouhal number the thrust coefficient decreases and the maximum propulsive efficiency reaches 75%. Results illustrate the kinematics required to transition between the high-efficiency and high-thrust regimes at high Reynolds number. Reynolds number effects are explored through a comparison with direct numerical simulations (DNS) at Re = 10 3 , and demonstrate that a higher efficiency is achieved at turbulence Reynolds numbers.The unsteady vortex dynamics through the heave-pitch cycle strongly influence the characterization of thrust and propulsive efficiency, and are classified into flow regimes based on performance and vortex structure.

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“…It has to be discussed whether the Kutta condition can be applied in the unsteady flexible propeller BEM model because the Kutta condition was proposed solely for steady flows [22]. Later, the Kutta condition has been modified for unsteady models, which had been questioned [23].…”

Section: The Kutta Condition For Flexible Propellersmentioning

confidence: 99%

Boundary Element Modelling Aspects for the Hydro-Elastic Analysis of Flexible Marine Propellers

Maljaars

Kaminski

Besten

2018

JMSE

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Boundary element methods (BEM) have been used for propeller hydrodynamic calculations since the 1990s. More recently, these methods are being used in combination with finite element methods (FEM) in order to calculate flexible propeller fluid-structure interaction (FSI) response. The main advantage of using BEM for flexible propeller FSI calculations is the relatively low computational demand in comparison with higher fidelity methods. However, the BEM modelling of flexible propellers is not straightforward and requires several important modelling decisions. The consequences of such modelling choices depend significantly on propeller structural behaviour and flow condition. The two dimensionless quantities that characterise structural behaviour and flow condition are the structural frequency ratio (the ratio between the lowest excitation frequency and the fundamental wet blade natural frequency) and the reduced frequency. For both, general expressions have been derived for (flexible) marine propellers. This work shows that these expressions can be effectively used to estimate the dry and wet fundamental blade frequencies and the structural frequency ratio. This last parameter and the reduced frequency of vibrating blade flows is independent of the geometrical blade scale as shown in this work. Regarding the BEM-FEM coupled analyses, it is shown that a quasi-static FEM modelling does not suffice, particularly due to the fluid-added mass and hydrodynamic damping contributions that are not negligible. It is demonstrated that approximating the hydro-elastic blade response by using closed form expressions for the fluid added mass and hydrodynamic damping terms provides reasonable results, since the structural response of flexible propellers is stiffness dominated, meaning that the importance of modelling errors in fluid added mass and hydrodynamic damping is small. Finally, it is shown that the significance of recalculating the hydrodynamic influence coefficients is relatively small. This fact might be utilized, possibly in combination with the use of the closed form expressions for fluid added mass and hydrodynamic damping contributions, to significantly reduce the computation time of flexible propeller FSI calculations.

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Influence of the wake model on the thrust of oscillating foil

Cited by 22 publications

References 27 publications

Study on the Hydrodynamic Performance of Typical Underwater Bionic Foils with Spanwise Flexibility

Study on the Hydrodynamic Performance of Typical Underwater Bionic Foils with Spanwise Flexibility

Variable thrust and high efficiency propulsion with oscillating foils at high Reynolds numbers

Boundary Element Modelling Aspects for the Hydro-Elastic Analysis of Flexible Marine Propellers

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