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    Wyświetlanie 1-6 z 6
    Tytuł:
    Experimental investigation of moonpool shapes on a ship with forward speed
    Autorzy:
    Sajjan, Sharanabasappa C.
    Surendran, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/320889.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Forum Nawigacyjne
    Tematy:
    drillships
    underwater exploration
    sloshing
    frequency range
    Froude number
    Opis:
    A moonpool is a feature of marine drilling platforms, drillships and diving support vessels, some marine research and underwater exploration or research vessels, and underwater habitats, in which it is also known as a wet porch. A floating platform with a moonpool is subjected to different forces due to sloshing and movement of the entrapped fluid in it, while the body is subjected to environmental loads like waves, winds, currents etc.,. Inside a moonpool considerable relative motions may occur, depending on shape and depth of the moonpool and the frequency range of the waves to which it is exposed. The vessel responses are entirely different in zero and non-zero Froude numbers. Later situation is paid attention in this study. There will be different water column elevations in the moonpool depending on the shapes. Two modes of responses are possible based on the shape of the moonpool viz., piston mode for square and sloshing mode for rectangular shape. An aspect ratio of 1:1 for square, 1:1.5 and 1:2 in case of rectangular shapes is considered during experimentation. Circular shaped moonpool is also tested for finding the response. The vessel is initially tested in a towing tank with different drafts and speeds based on Froude scaling. The different modes of oscillations of water column are measured using wave gauge and the vessel resistance is also studied, with and without moonpool. The water column elevation in moonpool may provide better insight to the designer to consider operational and safety parameters.
    Źródło:
    Annual of Navigation; 2019, 26; 151-162
    1640-8632
    Pojawia się w:
    Annual of Navigation
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Physical modeling of a fire with the use of the Froude number
    Autorzy:
    Zimny, Mateusz
    Powiązania:
    https://bibliotekanauki.pl/articles/391001.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
    Tematy:
    modelowanie fizykalne
    liczba Froude'a
    testy pożarowe
    physical modelling
    Froude number
    fire tests
    Opis:
    Testy pożarowe w małej skali (skali modelowej) od samego początku istnienia dziedziny Inżynierii Bezpieczeństwa Pożarowego były źródłem wielu cennych informacji na temat zjawisk zachodzących podczas spalania. Przez lata wykształciło się kilka metod obliczeniowych pozwalających wyznaczyć kryteria podobieństwa pożarów w rzeczywistej i małej skali geometrycznej. Celem niniejszego artykułu jest przedstawienie metody wykonywania testów pożarowych w skali modelowej z wykorzystaniem liczby Froude’a. Omówione zostały podstawy skalowania, warunki podobieństwa, jakie muszą zostać zachowane, sposoby opisywania zjawisk pożarowych, a także metody przeliczania parametrów pożaru ze skali rzeczywistej i modelowej. Przedstawiono również przykładowe badania fizykalne z wykorzystaniem pomniejszonych modeli badawczych. W sposób szczególny podkreślono, jak ważne są tego typu eksperymenty oraz jaka odpowiedzialność spoczywa na osobach, które je przeprowadzają. Motywacją do przeprowadzenia badań jest bowiem bezpieczeństwo ludzi, którzy przebywają w budynkach z zabezpieczeniami przeciwpożarowymi opartymi na testach w skali modelowej.
    Ever since the field of Fire Safety Engineering first came into existence, small-scale (model scale) fire tests were the source of much valuable information about the phenomena occurring during combustion. Over the years, several computational methods to determine the criteria for the similarity of fires on both a real and small geometric scale have been developed. The purpose of this article is to present a method of performing fire tests on a model scale using the Froude number. The basics of scaling, similarity conditions that must be preserved, ways of describing fire phenomena, as well as methods of calculating fire parameters from the real and model scale have been discussed. An example of physical tests with the use of reduced research models is also presented. What is particularly emphasized is how important these types of experiments are and what responsibility rests with the people who carry them ouvol. The motivation to conduct research is the safety of people who reside in buildings with fire protection based on model scale test.
    Źródło:
    Budownictwo i Architektura; 2019, 18, 1; 71-80
    1899-0665
    Pojawia się w:
    Budownictwo i Architektura
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental study of dam-break-like tsunami bore impact mechanism on a container model
    Autorzy:
    Chen, Cheng
    Chen, Jun
    Lin, Peng
    Chen, Chiwei
    Chen, Haozhe
    Powiązania:
    https://bibliotekanauki.pl/articles/260608.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    tsunami bore
    dam break
    container
    Froude number
    movement distance
    coast slope
    Opis:
    Tsunami disasters have frequently occurred in recent years. More and more researchers are focusing on this topic. To investi-gate the tsunami bore impact mechanism on a container model, a multi-functional slope-changing tsunami flume is built in this study. To simulate a tsunami bore, a dam-break wave was generated by a free-falling gate in a reservoir. A needle water level gauge and a high-speed camera were used to measure the tsunami wave heights and velocities for different storage water levels in the test flume, and the corresponding Froude numbers of tsunami waves were also calculated. The factors af-fecting the movement distance of the tsunami wave impacting the container model are explored in this experiment, and the results show that the movement distance is positively correlated with the storage water level, and negatively correlated with the container density and the coast slope.
    Źródło:
    Polish Maritime Research; 2020, 1; 53-59
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimizing the Seakeeping Performance of Ship Hull Forms Using Genetic Algorithm
    Autorzy:
    Bagheri, L.
    Ghassemi, H.
    Dehghanian, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/117211.pdf
    Data publikacji:
    2014
    Wydawca:
    Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
    Tematy:
    genetic algorithms
    Seakeeping Performance
    Ship Hull
    Hydrodynamics
    Ship Design
    Froude Number
    Seakeeping Calculation
    optimization
    Opis:
    Hull form optimization from a hydrodynamic performance point of view is an important aspect of ship design. This study presents a computational method to estimate the ship seakeeping in regular head wave. In the optimization process the Genetic Algorithm (GA) is linked to the computational method to obtain an optimum hull form by taking into account the displacement as design constraint. New hull forms are obtained from the well-known S60 hull and the classical Wigley hull taken as initial hulls in the optimization process at two Froude numbers (Fn=0.2 and Fn=0.3). The optimization variables are a combination of ship hull offsets and main dimensions. The objective function of the optimization procedure is the peak values for vertical absolute motion at a point 0.15LBP behind the forward perpendicular, in regular head waves.
    Źródło:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2014, 8, 1; 49-57
    2083-6473
    2083-6481
    Pojawia się w:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Shapes of an air Taylor bubble in stagnant liquids influenced by different surface tensions
    Autorzy:
    Lertnuwat, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/265869.pdf
    Data publikacji:
    2018
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    turbulencje
    napięcie powierzchniowe
    model Taylora
    Dumitrescu-and-Taylor model
    Froude number
    surface tension
    Taylor bubble
    turbulence
    Opis:
    The aim of this work is to propose an empirical model for predicting shapes of a Taylor bubble, which is a part of slug flows, under different values of the surface tension in stagnant liquids by employing numerical simulations. The k - turbulence model was used in the framework of finite volume method for simulating flow fields in a unit of slug flow and also the pressure distribution on a Taylor bubble surface. Assuming that an air pressure distribution inside the Taylor bubble must be uniform, a grid search method was exploited to find an appropriate shape of a Taylor bubble for six values of surface tension. It was found that the shape of a Taylor bubble would be blunter if the surface tension was increased. This was because the surface tension affected the Froude number, controlling the flow around a Taylor bubble. The simulation results were also compared with the Taylor bubble shape, created by the Dumitrescu-and-Taylor model and former studies in order to ensure that they were consistent. Finally, the empirical model was presented from the simulation results.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2018, 23, 1; 79-90
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hydrodynamics of DARPA SUBOFF submarine at shallowly immersion conditions
    Autorzy:
    Efremov, D. V.
    Milanov, E. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/115979.pdf
    Data publikacji:
    2019
    Wydawca:
    Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
    Tematy:
    hydrodynamics
    froude number
    Defense Advanced Research Projects Agency (DARPA)
    submarine
    submarine model
    suboff model
    shallowly immersion conditions
    submarine simulation model
    Opis:
    Recently, the submarine missions are often evolving into operating to littoral areas, which require operating in shallow water. Such shallow water operations strongly contrast with the traditional ones due to the effect of a close to free water surface expressed mainly by surface suction force. This influence is particularly important for submarine maneuverability accounting for restricted area available. The prediction of submarine behavior in similar conditions requires adequate mathematical model and understanding of the additional hydrodynamic load generated near the surface region. The paper is aimed for better understanding of these issues and relating to development of a submarine simulation model, the experimental program of towing and PMM captive tests of DARPA Suboff submarine model were conducted at a towing tank. The influence of phenomenon such as effect of a close to free surface and Froude number at hydrodynamic forces and moments including control surfaces effectiveness were investigated and also was estimated directional stability of motion in horizontal plane.
    Źródło:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2019, 13, 2; 337-342
    2083-6473
    2083-6481
    Pojawia się w:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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