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Wyszukujesz frazę "hydrodynamic coefficients" wg kryterium: Temat


Wyświetlanie 1-2 z 2
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:
Forced motion CFD simulation and load refinement evaluation of floating vertical-axis tidal current turbines
Autorzy:
Zhang, Wanchao
Zhou, Yujie
Wang, Kai
Zhou, Xiaoguo
Powiązania:
https://bibliotekanauki.pl/articles/1573876.pdf
Data publikacji:
2020
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
vertical-axis tidal current turbine
hydrodynamic loads
pitching motion
added mass
damping coefficients
Opis:
Simulation of the hydrodynamic performance of a floating current turbine in a combined wave and flow environment is important. In this paper, ANSYS-CFX software is used to analyse the hydrodynamic performance of a vertical-axis turbine with various influence factors such as tip speed ratio, pitching frequency and amplitude. Time-varying curves for thrust and lateral forces are fitted with the least squares method; the added mass and damping coefficients are refined to analyse the influence of the former factors. The simulation results demonstrate that, compared with nonpitching and rotating turbines under constant inflow, the time-varying load of rotating turbines with pitching exhibits an additional fluctuation. The pitching motion of the turbine has a positive effect on the power output. The fluctuation amplitudes of thrust and lateral force envelope curves have a positive correlation with the frequency and amplitude of the pitching motion and tip speed ratio, which is harmful to the turbine’s structural strength. The mean values of the forces are slightly affected by pitching frequencies and amplitudes, but positively proportional to the tip speed ratio of the turbine. Based upon the least squares method, the thrust and lateral force coefficients can be divided into three components, uniform load coefficient, added mass and damping coefficients, the middle one being significantly smaller than the other two. Damping force plays a more important role in the fluctuation of loads induced by pitching motion. These results can facilitate study of the motion response of floating vertical-axis tidal current turbine systems in waves.
Źródło:
Polish Maritime Research; 2020, 3; 40-49
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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