WAN Zhong(1988-), male, Ph.D. candidate, senior engineer, E-mail: hzwz2115@sjtu.edu.cn.
In order to understand the influence of bow shape on ice resistance and provide guidelines for hull line design in the early design stage, an investigation of the impact of bow shape on ice resistance for the Arctic LNG carriers is carried out based on semi-empirical methods. Firstly, some typical semi-empirical formulas developed for ice resistance estimation of cargo carriers in different ice conditions are summarized. Then, formulas appropriate for ice resistance estimation of Arctic LNG carriers under different ice conditions are verified according to the result comparison between semi-empirical formulas and experimental tests. The comparison result indicates that the Lindqvist formula is appropriate for ice resistance estimation in level ice conditions, Zuev and Dobrodeev formula for ice resistance estimation in broken ice conditions, and Dobrodeev formula for ice resistance estimation in brash ice conditions. After that, the parameters considered in the selected formulas are summarized, and the influence of critical parameters on ice resistance is analyzed. Some parameters describing the ship's bow shape characteristic like ship breadth, waterline angle and stem angle greatly influence the ice resistance. Ice resistance increases with both the growth of ship breadth under all ice conditions and the growth of stem angle in level ice and broken ice conditions while ice resistance decreases with the development of waterline angle under all ice conditions. Finally, the optimization of the bow shape is discussed, and an optimized bow shape with both a large waterline angle and low stem angle is proposed. The optimized bow shape can decrease ice resistance by 9.9% in the level ice condition and reduce ice resistance by 11.3% in the brash ice condition.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |