쇄빙 연구선의 저항성능 및 진동개선에 관한 연구

Abstract

Today, the increase in concern about the design of icebreakers and icebreaking ships is caused by the development on Arctic areas. When an icebreaker is designed, one of the main goals is to minimize the forces resulting from crushing and breaking the ice. The spoon-shaped bow and round hull in order to minimize the icebreaking forces, have poor hydrodynamic efficiency and seekeeping characteristics, and make the icebreaker susceptible to slamming. For this reason, the hull of an icebreaker is often a compromise between minimize ice resistance, maneuverability in ice, low hydrodynamic resistance, and adequate open water characteristics. Some icebreakers have a hull that is wider in the bow than in the stern. These so-called “reamers” increase the width of the ice channel and thus reduce ice frictional resistance in the aftship as well as improve the ship’s maneuverability in ice. However, it is well known that the reamers suffer from an additional resistance in open water.

In this thesis, basic design process for an icebreaker is introduced, a reamers’ effects on resistance performance in open water is examined by model tests and a free and forced vibration analysis is performed to verify vibration problems.

To examine reamers’ phenomenon by model tests, the additional resistance in open water of the 6,950-ton research icebreaker model with different type reamers is measured at the circulating water channel of the Chosun university. Various combinations of ship speeds and reamer types are tested at two draught conditions. These experimental results with different reamers are compared to the results without reamers. It can be concluded that smaller the angle between the designed waterplane and the buttock line near reamers, the better resistance performance in open water. In addition to the study on hydrodynamic effects of reamers, a free and forced vibration analysis of the global icebreaker structure using ANSYS program based on 3-dimensional finite element (FE) method is performed at various conditions (full and 90 % load). It can be concluded that no vibration problem relating to hull is expected.