|
4. PREDICHONS AND COMPARISONS
4.1 General
In order to assess the relative merits of the single source or multi-source methods of predicting hydrodynamic derivatives, we have calculated the values according to a range of different methods. Where possible these have been combined with a comparison of model test data and full-scale manoeuvring performance.
As previously described, two ships have been used for this study;
i) ESSO OSAKA: A large tanker selected as the benchmark test case by the ITTC. Whilst it is an old hull form, we have not yet mastered its complexities and hence it remains valid.
ii) GOLDEN PRINCESS: A modern, twin-screw cruise ship with high windage, designed for high manoeuvrability.
The principal characteristics of these two ships are presented in Table 2 in the Appendix.
4.2 Results for the ESSO OSAKA
The linear and non-linear derivatives and added mass terms for the ESSO OSAKA were calculated using the following methods;
- BMT [19] - Clarke[11]
- Jones [11] - Wagner-Smitt [11]
- Norrbin [11] - Inoue [12]
- Kijima [15] - Ankudinov [17]
- Khattab [18] - ITTC benchmark [1]
- KRISO tests [1] - Hydronautics test data [1], [9]
- SNU test data [1] - Abkowitz SI data [5]
- Rhee SI data [6] - Mean values of all data
The methods highlighted in bold text were used initially to compare the forces and moments in order to select the prediction methods to use in the comparison of simulated manoeuvring performance. The comparison of the forces and moments determined using these methods are shown below in Figures 3-6.
Fig.3 Sway Force for Pure Drift-ESSO OSAKA
Fig.4 Sway Force for Pure Yaw-ESSO OSAKA
Fig.5 Yaw Moment for Pure Drift-ESSO OSAKA
Fig.6 Yaw Moment for Pure Yaw-ESSO OSAKA
The calculated forces and moments due to pure drift and pure yaw for all of these methods used are shown in Figures 15-18 in the Appendix.
|
