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    Wyświetlanie 1-6 z 6
    Tytuł:
    DeepCwind semi-submersible floating offshore wind turbine platform with a nonlinear multi-segment catenary mooring line and intermediate buoy
    Autorzy:
    Motallebi, Mohammad
    Ghassemi, Hassan
    Shokouhian, Mehdi
    Powiązania:
    https://bibliotekanauki.pl/articles/24202503.pdf
    Data publikacji:
    2022
    Wydawca:
    Akademia Morska w Szczecinie. Wydawnictwo AMSz
    Tematy:
    semi-submersible floating platform
    offshore wind turbine
    dynamic response
    catenary mooring system
    intermediate buoy
    strain and tension
    Opis:
    In this paper, to improve the mechanical behavior of DeepCwind semi-submersible floating offshore wind turbine (FOWT) platform mooring lines, the nonlinear catenary cables of the platform were divided into multi-segment and intermediate buoys. Mathematical formulations of the boundary element method (BEM) governing the dynamics of mooring line systems with buoy devices were described. This study was applied to the OC4-DeepCwind semi-submersible FOWT platform, which is designed for a 200-meter water depth with mooring lines consisting of three catenary steel chain cables at 120° angles to each other. The dynamic response of the multi-segment catenary mooring lines with different buoy radiuses and different positions along the cables was investigated. The full-scale platform was modeled in ANSYS-AQWA software, and the simulations were performed under harsh offshore conditions. The mooring line’s general arrangement, tension, strain and uplift force for different buoy radiuses and their position along the cable are presented and discussed. Moreover, platform motions in three directions (surge, heave, and pitch) were also analyzed. It was concluded that by correctly selecting the buoy volume and position along the cable, the tension of the cable may be reduced by up to 45%. By incorrectly selecting the buoy, the results caused adverse effects.
    Źródło:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2022, 69 (141); 20--34
    1733-8670
    2392-0378
    Pojawia się w:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Power and thrust coefficients of the horizontal axis tidal stream turbine with different twist angles, blade numbers, and section profiles
    Autorzy:
    Abbasi, Alireza
    Ghassemi, Hassan
    Molyneux, David
    Powiązania:
    https://bibliotekanauki.pl/articles/135026.pdf
    Data publikacji:
    2019
    Wydawca:
    Akademia Morska w Szczecinie. Wydawnictwo AMSz
    Tematy:
    HATST
    twist angle
    blade profile
    blade number
    power coefficient
    thrust coefficients
    Opis:
    The purpose of this research was to investigate the power and thrust coefficients of a horizontal axis tidal stream turbine (HATST) with different blade geometries, including twist angles, blade numbers, and section profiles. The RANS equations and Star-CCM+ commercial software were used to numerically analyze these variables. Furthermore, the turbulence model used in this study is a Realisable k-ε turbulent model. Nine different models were defined by changing the twist angle, thickness, camber, and blade numbers. The results are presented, and the power and thrust coefficients are compared against TSR for each of the nine different models. The pressure distribution and flow velocity contour are also presented and discussed.
    Źródło:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2019, 57 (129); 11-20
    1733-8670
    2392-0378
    Pojawia się w:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Vibration equations of the coupled torsional, longitudinal, and lateral vibrations of the propeller shaft at the ship stern
    Autorzy:
    Firouzi, Jabbar
    Ghassemi, Hassan
    Vakilabadi, Karim Akbari
    Powiązania:
    https://bibliotekanauki.pl/articles/135360.pdf
    Data publikacji:
    2020
    Wydawca:
    Akademia Morska w Szczecinie. Wydawnictwo AMSz
    Tematy:
    vibration equations
    coupled vibration
    shaft and propeller
    added mass
    ship stern
    hydrodynamic coefficients
    Opis:
    A propeller shaft generally experiences three linear forces and three moments, the most important of which are thrust, torque, and lateral forces (horizontal and vertical). Thus, we consider 4DOFs (degrees of freedom) of propeller shaft vibrations. This paper is presented to obtain the vibration equations of the various coupled vibrations of the propeller shaft at the stern of a ship (including coupled torsional-axial, torsional-lateral, axial-lateral, torsional-axial, and lateral vibrations). We focused on the added hydrodynamic forces (added mass and added damping forces) due to the location of the propeller behind the ship. In this regard, the 4DOFs of the coupled vibration (torsional-longitudinal and lateral vibrations in the horizontal and vertical directions) equations of shaft and propeller systems located behind a ship were extracted with and without added mass and damping forces. Also, the effect of mass eccentricity was considered on vibrations occurring at the rear of the ship.
    Źródło:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2020, 61 (133); 121-129
    1733-8670
    2392-0378
    Pojawia się w:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation into a hybrid mooring system with hydrodynamic response and mooring tension from a DeepCwind floating wind turbine
    Autorzy:
    Ganjgani, Arman Aghaei
    Ghassemi, Hassan
    Ghiasi, Mahmoud
    Powiązania:
    https://bibliotekanauki.pl/articles/24202541.pdf
    Data publikacji:
    2022
    Wydawca:
    Akademia Morska w Szczecinie. Wydawnictwo AMSz
    Tematy:
    DeepCwind platform
    BEM
    buoys
    clump weight
    catenary mooring line
    Opis:
    This paper investigates the effect of buoys and a clump weight on the mooring lines and the dynamic response of the floating platform. The full-scale of the OC4-DeepCwind semisubmersible FOWT platform is analyzed using the boundary element method (BEM) with ANSYS-AQWA software, when considering regular wave conditions. Platform motions and mooring line tension in the surge, heave, and pitch are presented and discussed in the time domain analyses (TDA) and frequency domain analyses (FDA). Validation is performed by compression of the platform motion RAO and the fairlead tension RAO magnitudes in the surge, heave, and pitch (for both numerical and experimental data) under seven sea states’ regular waves. The results show that increasing the number of buoys at a constant volume decreases the surge and pitch motion amplitude, while the heave motion increases slightly. Adding the buoy and clump weight (type 1) to the mooring line reduces the oscillation amplitude tension. In addition, raising the number of buoys increases the oscillation tension.
    Źródło:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2022, 71 (143); 11--21
    1733-8670
    2392-0378
    Pojawia się w:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ship nonlinear roll motion identification using artificial neural network
    Autorzy:
    Mousavi, Seyed Mohamadreza
    Khoogar, Ahmad Reza
    Ghassemi, Hassan
    Powiązania:
    https://bibliotekanauki.pl/articles/24202591.pdf
    Data publikacji:
    2022
    Wydawca:
    Akademia Morska w Szczecinie. Wydawnictwo AMSz
    Tematy:
    nonlinear roll motion
    dynamic identification
    DTMB 5415
    roll decay
    artificial neural network
    Opis:
    The solution of the nonlinear equation for a ship’s rotational motion around its longitudinal axis, even with simplifying assumptions, is complicated. This oscillatory motion, which is known as the roll motion, is generated when the ship sails in the waves, and the irregular behavior of the waves causes time-varying dynamics. Calculating the ship’s roll response is possible by determining roll equation coefficients. In the current study, the coefficients were determined from the dynamic response of the ship using a training feed-forward neural network. The training was carried out in two modes: as a free swing in calm water and forced oscillation in irregular waves. The DTMB 5415 vessel was selected as the case study ship. The results of the simulation by the neural network were validated by numerical analysis and model test results.
    Źródło:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2022, 72 (144); 65--74
    1733-8670
    2392-0378
    Pojawia się w:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Calculating the second-order hydrodynamic force on fixed and floating tandem cylinders
    Autorzy:
    Motallebi, Mohammad
    Ghafari, Hamidreza
    Ghassemi, Hassan
    Shokouhian, Mehdi
    Powiązania:
    https://bibliotekanauki.pl/articles/135350.pdf
    Data publikacji:
    2020
    Wydawca:
    Akademia Morska w Szczecinie. Wydawnictwo AMSz
    Tematy:
    fixed cylinder
    floating cylinder
    second order hydrodynamic force
    diffracted wave
    potential theory
    Opis:
    In this paper, the second-order hydrodynamic force on fixed and floating tandem cylinders has been calculated and different parameters have been taken into consideration. An incident wave is diffracted by the fixed cylinder, and as a result low-frequency waves radiate toward the floating cylinder and cause low-frequency second-order hydrodynamic forces to act on the surface of the floating cylinder. The interactions between the fixed and floating cylinders have been investigated by changing the distance between them, as well as the draft and radius of the floating cylinder. By employing perturbation series analysis over the wetted surface, the second-order wave excitation force has been calculated. The maximum force applied on the floating cylinder becomes non-dimensional when considering it with and without the fixed cylinder. The results showed the effect that the existence of the fixed cylinder had on the increase in the second-order forces is quite evident where, for a significant parameter of the floating cylinder, the force in the heave direction was enhanced by up to 1.55 times.
    Źródło:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2020, 62 (134); 108-115
    1733-8670
    2392-0378
    Pojawia się w:
    Zeszyty Naukowe Akademii Morskiej w Szczecinie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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