Investigation of the Pre-Swirl Stator Effects to the Ship Resistance and Ship Motions
| Autor: | Mao, Yao-Tang, 毛耀堂 |
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| Rok vydání: | 2018 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 106 The fuel efficiency in seaway becomes more important due to environmental regulations, and speed loss in seaway is required to evaluate as the weather factor in EEDI. To obtain the weather factor, the simulations of self-propulsion tests both in calm water and in seaway have to be carried out. Y-Fin is a pre-swirl stator like energy-saving device, and it is designed to recover the rotational energy. The researches on the energy-saving devices are usually on the resistance in calm water. In this thesis, the resistances and motions of a container ship with Y-Fin, in calm water and in waves are computed, and the Y-Fin effects to the ship resistances and motions are then analyzed. We first calculated the forces motions on Y-Fin alone in waves, and a nonlinear relationship between the incoming waves and Y-Fin responses is found. The resistances and motions of a container ship with Y-Fin at different speeds are then computed. The results show that the resistance increased in calm water due to Y-Fin is from the frictional drag. However, the resistances in waves are decreased due to Y-Fin at higher ship speeds. Also, both heave and pitch motions are decreased by a small amount due to Y-Fin. The self-propulsions of this ship are then simulated in calm water and in waves. The flow field in wake is analyzed, and it can be seen that Y-Fin has significant effects to both the axial and tangential velocities. Therefore, the propulsive efficiency is changed due to Y-Fin. Finally, the speed loss in seaway is estimated. In order to obtain the speed loss in seaway, it is required to simulate self-propulsions of a model scale ship both in calm water and in seaway. The full scale speed loss thus can be computed from ship speeds obtained at the same power in both calm water and seaway. For the speed loss, although the Y-Fin has its advantage, the impact is relatively small. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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