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    Wyświetlanie 1-12 z 12
    Tytuł:
    Numerical investigation of the flow around wing tips
    Autorzy:
    Koronowicz, T.
    Tuszkowska, T.
    Wilczyński, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/1953943.pdf
    Data publikacji:
    2000
    Wydawca:
    Politechnika Gdańska
    Tematy:
    vortex theory
    lifting surface model
    hydrofoil
    Opis:
    The paper dwells with the problems of modelling the flow around a wing tip and tip vortex cavitation. The theoretical bases of the vorticity method and vorticity calculation models for design and estimation of hydrodynamic characteristics of the hydrofoil are presented. Basic assumptions of a double layer lifting surface model are described. A double layer lifting surface model enables proper modelling of the phenomena occurring in the flow around a hydrofoil tip and especially the generation of a free vortices system.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2000, 4, 2; 203-212
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal design and numerical simulation on fish-like flexible hydrofoil propeller
    Autorzy:
    Xue, G.
    Liu, Y.
    Zhang, M.
    Zhang, W.
    Zhang, J.
    Luo, H.
    Jia, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/259984.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    bionics
    flexible hydrofoil
    phase angle
    hydrodynamic coefficient
    Opis:
    Hydrofoil is widely used in underwater vehicle for the excellent hydrodynamic characteristics. Currently, researches are mostly about the rigid hydrofoil while the flexible hydrofoil, like the caudal fin, has not been studied adequately. In this paper, the fish was regarded as the bionic object. Then the kinematics model to describe the fish swimming was put forward. A fin-peduncle propulsion mechanism was designed based on the kinematics model to achieve the similar sine curve swimming model. The propulsion mechanism was optimized by Matlab to reduc the deviation between the output curve of the fin-peduncle propulsion mechanism and the ideal motion trajectory. Moreover, the motion phase angles among flexible articulations are optimized to reduce fluid resistance and improve propulsive efficiency. Finally, the fish-like hydrofoil oscillation is simulated by fluid-solid coupling method based on the Fluent. It was shown that the optimized flexible fish-like oscillation could generate the motion that follows the similar law of sine. The propulsive efficiency of oscillating hydrofoil propeller is much higher than that of the screw propeller, and the flexible oscillation has higher propulsive efficiency than the rigid oscillation without obvious fluid resistance increase.
    Źródło:
    Polish Maritime Research; 2016, 4; 59-66
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical analysis of the effect of flexibilityon the propulsive performance of a heaving hydrofoil undergoing sinusoidal and non-sinusoidal motions
    Autorzy:
    Li, Fengkun
    Yu, Pengyao
    Wang, Qiang
    Li, Guangzhao
    Wu, Xiangcheng
    Powiązania:
    https://bibliotekanauki.pl/articles/2033183.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    fluid-structure interaction
    flexible hydrofoil
    non-sinusoidal motions
    propulsive characteristics
    Opis:
    Numerical simulations of fluid‒structure interaction (FSI) on an elastic foil heaving with constant amplitude in freestream flow are carried out at a low Reynolds number of 20,000. The commercial software STAR-CCM+ is employed to solve the flow field and the large-scale passive deformation of the structure. The results show that introducing a certain degree of flexibility significantly improves the thrust and efficiency of the foil. For each Strouhal number St considered, an optimal flexibility exists for thrust; however, the propulsive efficiency keeps increasing with the increase in flexibility. The visualisation of the vorticity fields elucidates the improvement of the propulsive characteristics by flexibility. Furthermore, the mechanism of thrust generation is discussed by comparing the time-varying thrust coefficient and vortex structure in the wake for both rigid and elastic foils. Finally, in addition to sinusoidal motions, we also consider the effect of non-sinusoidal trajectories defined by flattening parameter S on the propulsive characteristics for both rigid and elastic foils. The non-sinusoidal trajectories defined by S=2 are associated with the maximum thrust, and the highest values of propulsive efficiency are obtained with S=0.5 among the cases considered in this work.
    Źródło:
    Polish Maritime Research; 2021, 4; 4-19
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A New Multidisciplinary Approach For Three-Dimensional Foil Machining
    Autorzy:
    Jaouen, R.
    Martineau, J. P.
    Hascoet, J.-Y.
    Damay, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/971241.pdf
    Data publikacji:
    2009
    Wydawca:
    Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
    Tematy:
    adapted tool trajectories
    5 axis machining machining peaks
    hydrofoil lspropellers
    hydrodynamic
    Opis:
    The context of this paper implies disciplines of mechanical design, machining and hydrodynamics behaviours applied to propellers. Performances of propellers are linked with their shape and their surface texture. To optimise hydrodynamics behaviours, it is demonstrated in this paper that required polishing operation is not essential. To study the influence of an predefined surface texture on the performances of a three-dimensional foil, a comparative analysis is conducted. The presented methodology allows the definition of tool paths, according to the desired surface texture and upstream flow. Three foils are machined, and their performances are compared to each other: the first, considered as the reference, has a surface roughness like mirror, the second features machined peaks parallel to the upstream flow and the third has machined peaks following streamlines obtained by Computational Fluid Dynamics for operating conditions. The validation of this method is experimental: on the one hand by the manufacturing of foils following pre-established trajectories, and on the other hand by the functional test in hydrodynamic tunnel. This paper presents the methodology steps, and the hydrodynamic behaviours that the three different foils show. In a first approach, the different surface textures do not influence the lift coefficient but strongly influence the drag coefficient of a foil. Furthermore several hypotheses educed from the observed tendencies are discussed.
    Źródło:
    Journal of Machine Engineering; 2009, 9, 1; 5-17
    1895-7595
    2391-8071
    Pojawia się w:
    Journal of Machine Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    High-speed catamaran’s longitudinal motion attenuation with active hydrofoils
    Autorzy:
    Hu, K.
    Ding, Y.
    Wang, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/259910.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    High-speed catamaran
    longitudinal motion attenuation
    2.5D theory
    hydrofoil
    Opis:
    This paper mainly studies the longitudinal motion prediction method and control technology of high-speed catamaran using the active hydrofoils. To establish the longitudinal motion equations of the ship basing on the 2.5D theory. Using the CFD software to obtain the hydrodynamic data of the hydrofoil. Bring the hydrodynamic expression of hydrofoils into the longitudinal motion equations of the ship. Predicting the longitudinal motion of High-speed catamaran before and after added the hydrofoils. A specific catamaran has been predicted with this approach, the result indicates this approach is workable and this prediction approach provides the theoretical basis for assessing the stabilization ability of appendages and possess the engineering practical value.
    Źródło:
    Polish Maritime Research; 2018, S 2; 56-61
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effects of boundary layer control method on hydrodynamic characteristics and tip vortex creation of a hydrofoil
    Autorzy:
    Ghadimi, P.
    Araz-Tanha, A.
    Nemati-Kourabbasloo, N.
    Tavakoli, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/259965.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    steady water injection
    boundary layer control
    hydrofoil
    NACA 0015
    tip vortex
    Opis:
    There is currently a significant focus on using boundary layer control (BLC) approach for controlling the flow around bodies, especially the foil sections. In marine engineering this is done with the hope of increasing the lift – to – drag ratio and efficiency of the hydrofoils. In this paper, effects of the method on hydrodynamic characteristics and tip vortex formation of a hydrofoil are studied. Steady water injection at the tip of the hydrofoil is simulated in different conditions by using ANSYS-CFX commercial software. Validity of the proposed simulations is verified by comparing the obtained results against available experimental data. Effects of the injection on the lift, drag, and lift – to – drag ratio are studied and the ranges within which the injection has the most positive or negative effects, are determined. Furthermore, flow pattern and pressure variation are studied upon the water injection to determine the most positive and negative case and to ascertain the main reasons triggering these phenomena.
    Źródło:
    Polish Maritime Research; 2017, 2; 27-39
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of flow pattern on a hydrofoil with structural and profile modification
    Autorzy:
    Chada, Jithendra Sai Raja
    Rao, B. S. V. Rama
    Powiązania:
    https://bibliotekanauki.pl/articles/2106431.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Koszalińska. Wydawnictwo Uczelniane
    Tematy:
    hydrofoil
    groves
    angle of attack
    CFD
    fine mesh
    validation
    wodolot
    kąt natarcia
    walidacja
    Opis:
    Moving through water takes much more effort than walking through air, and this explains why ships travel much more slowly than automobiles and aircraft. Water is almost 1000 times denser than air, so most of the energy produced by a boat is taken up by dragging (water resistance). Hydrofoils travel much more quickly than ordinary boats, not by pushing through water but by raising the hull (the main body) of the boat upward so it can glide above the waves. Hydrofoil is one of the typical factors that affect the vortex structure and flow characteristics of hydraulic machinery. In order to enhance the utilisation efficiency of hydraulic machinery in marine energy, parallel grooves are proposed and applied to the hydrofoil. Following that, a numerical analysis is performed using the SST k- turbulence model, and the effects of the hydrofoil profile, the angle of attack and the flow are investigated. The profiles of NACA 0066, NACA 8412, NACA M2 and RAE 104 are considered for the study. The performance is analysed based on the lift to drag ratio. The best model from this is given with surface modification and the flow study is carried out at different angles of attack. The modified profile of NACA 8412 with parallel groves has shown the highest lift to drag ratio at a 12 degree angle of attack.
    Źródło:
    Journal of Mechanical and Energy Engineering; 2022, 6, 1; 27--32
    2544-0780
    2544-1671
    Pojawia się w:
    Journal of Mechanical and Energy Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Repellence Effect of the New Sound for Underwater Speaker of Hydrofoil
    Autorzy:
    Nakashima, T.
    Kobayashi, N.
    Yamada, H.
    Katsumata, T.
    Yoshida, R.
    Kato, H.
    Okabe, H.
    Kawazu, I.
    Yanase, Y.
    Omine, M.
    Terada, M.
    Sugioka, H.
    Kyo, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/116522.pdf
    Data publikacji:
    2015
    Wydawca:
    Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
    Tematy:
    Underwater Speaker (UWS)
    Hydrofoil
    Underwater Speaker Sound
    Humpback Whale
    New Sound
    Cetaceans
    Acoustics
    Hydroacoustics
    Opis:
    In order to prevent hydrofoil colliding with cetaceans, the underwater speaker (UWS) has been installed to repel cetaceans. Yamada et al. (2012) analyzed and devised the UWS sound as it fits the cetaceans' acoustic properties to prevent the collision furthermore. The new UWS sound was devised and synthesized by Yamada et al. (2015) with expectation of avoiding collision with large cetaceans (Patent applied for, JP2014-171411). In this research project, the new UWS sound was investigated by the playback experiment on humpback whale (Megaptera novaeangliae) and by sighting survey in the actual hydrofoil shipping service route. As a result, a physiological and behavioral change of the humpback whale was observed in the playback experiment of the new UWS sound, and the chance of hydrofoil encountering cetaceans of the new UWS sound was smaller than that of the previous UWS sound. Therefore, the improvement of the new UWS sound was confirmed. Lastly, we wish this research project would contribute toward the safer cruise of hydrofoil in the future.
    Źródło:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2015, 9, 2; 207-211
    2083-6473
    2083-6481
    Pojawia się w:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Shape optimization of a submerged 2D hydrofoil and improvement of its lift-to-drag ratio using CFDbased mesh morphing-adjoint algorithm
    Autorzy:
    Nazemian, Amin
    Ghadimi, Parviz
    Ghadimi, Aliakbar
    Powiązania:
    https://bibliotekanauki.pl/articles/24202520.pdf
    Data publikacji:
    2022
    Wydawca:
    Akademia Morska w Szczecinie. Wydawnictwo AMSz
    Tematy:
    NACA0012 hydrofoil
    free surface
    lift-to-drag ratio
    Ansys-Fluent
    mesh morphing
    adjoint solver
    Opis:
    Hydrofoils are utilized as instruments to improve the hydrodynamic performance of marine equipment. In this paper, the motion of a 2D NACA0012 hydrofoil advancing in water near the free surface was simulated, and a mesh morphing-adjoint based optimizer was used to maximize its lift-to-drag ratio. Ansys-Fluent was used as a CFD solver, and a mesh-morphing tool was used as a geometry reconstruction tool. Furthermore, the Adjoint solver was applied to evaluate the sensitivities of the objective function to all solution variables. Defined control points around the geometry are design variables that move in an appropriate direction through shape sensitivity. The computational results were validated against available experimental data and published numerical findings. Subsequently, different hydrodynamic characteristics of the optimized hydrofoil were compared to those of the original model at different angles of attack of 3, 3.5, 4, 4.5, 5, 5.5, 6, and 6.5°, and optimized shapes were determined. It was observed that the shape of the optimized hydrofoil was totally dependent on the angle of attack, which produced different lift-to-drag ratios. It is also seen that among higher angles of attack at which improvement in the L/D ratio became steady, the drag coefficient was the lowest at 5°. Therefore, it can be concluded that the appropriate angle of attack for a hydrofoil installation on the ship hull is 5°. Further investigation was conducted concerning the evolution of shape optimization, sensitivity analysis, free surface elevation, flow characteristics, and hydrodynamic performance of the hydrofoil at a 5° angle of attack.
    Źródło:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2022, 70 (142); 27--40
    1733-8670
    2392-0378
    Pojawia się w:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical simulation of viscid flow around hydrofoil
    Autorzy:
    Dymarski, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/259633.pdf
    Data publikacji:
    2006
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    lepki napływ dookoła wodolotu
    metoda ograniczona
    viscid flow around hydrofoil
    Spalart-Allmaras model
    finite volume method
    SOLAGA
    Opis:
    This paper presents results of application of a viscid fluid model to calculate flow around a finite-span hydrofoil. The presented calculations were performed with the use of SOLAGA software developed by this author. The used theoretical model of viscid liquid motion was described, consisted of averaged liquid motion equations and Spalart-Allmaras one-equation model of turbulence. Also, a numerical model based on the finite volume method was shortly presented. Calculation results were shown in the form of distribution diagrams of pressures, longitudinal component of velocity and longitudinal component of rotation velocity. Additionally, the presented characteristics of the lifting force coefficient and drag force coefficient were compared with experimental data.
    Źródło:
    Polish Maritime Research; 2006, 1; 8-14
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of impeller shape on solid particle suspension
    Autorzy:
    Rieger, F.
    Jirout, T.
    Ceres, D.
    Seichter, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/185746.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    mixing
    axial impeller
    hydrofoil impeller
    just-suspended impeller speed
    electrochemical metod
    mieszanie
    wirnik osiowy
    prędkość wirnika
    metoda elektrochemiczna
    Opis:
    This paper deals with the effect of impeller shape on off-bottom particle suspension. On the basis of numerous suspension measurements, correlations are proposed for calculating the just-suspended impeller speed for a standard pitched four-blade turbine and three types of hydrofoil impellers produced by TECHMIX for several particle sizes and for a wide range of particle concentrations. The suspension efficiency of the tested impellers is compared with the efficiency of a standard pitched blade turbine on the basis of the power consumption required for off-bottom suspension of solid particles. It is shown that the standard pitched blade turbine needs highest power consumption, i.e. it exhibits less efficiency for particle suspension than hydrofoil impellers produced by TECHMIX.
    Źródło:
    Chemical and Process Engineering; 2013, 34, 1; 139-152
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Review of numerical models of cavitating flows with the use of the homogeneous approach
    Autorzy:
    Niedźwiedzka, A.
    Schnerr, G. H.
    Sobieski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/239953.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sheet cavitation
    cloud cavitation
    homogeneous models
    steady-state
    unsteady
    hydrofoil
    venturi
    cylinder
    model jednorodny
    stan stabilny
    stan ustalony
    niestacjonarny
    hydropłat
    Opis:
    The focus of research works on cavitation has changed since the 1960s; the behaviour of a single bubble is no more the area of interest for most scientists. Its place was taken by the cavitating flow considered as a whole. Many numerical models of cavitating flows came into being within the space of the last fifty years. They can be divided into two groups: multifluid and homogeneous (i.e., single-fluid) models. The group of homogenous models contains two subgroups: models based on transport equation and pressure based models. Several works tried to order particular approaches and presented short reviews of selected studies. However, these classifications are too rough to be treated as sufficiently accurate. The aim of this paper is to present the development paths of numerical investigations of cavitating flows with the use of homogeneous approach in order of publication year and with relatively detailed description. Each of the presented model is accompanied by examples of the application area. This review focuses not only on the list of the most significant existing models to predict sheet and cloud cavitation, but also on presenting their advantages and disadvantages. Moreover, it shows the reasons which inspired present authors to look for new ways of more accurate numerical predictions and dimensions of cavitation. The article includes also the division of source terms of presented models based on the transport equation with the use of standardized symbols.
    Źródło:
    Archives of Thermodynamics; 2016, 37, 2; 71-88
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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