200,000m3급 LNG선의 선미설계에 관한 연구

Abstract

The demand for LNG has been on the rise for the past few years. Hence the concept of very large LNG carriers is being considered by many shipyards today. The designs are however limited by dimensions such as the draft, length and air draught that are available at the loading and discharge ports. Ships of such proportions demand larger power. The new range of vessels will have wider beams and shallower drafts. This causes a rethinking in terms of the aft body design and the wake distribution patterns. This thesis investigates the effect of transom stern immersion and stern profile angle in LNG carriers. The transom stern immersion is determined to minimize stern wave resistance. At the stern bottom profile, sufficient clearance is given between the propeller and the hull to reduce propeller-hull interaction. Ships with transom immersions, generate stern waves which have a significant impact on the total resistance of the ship. The resistance contribution of this component, studied in detail, can be reduced to a certain extent. In this thesis, the hull-form of a 200,000 m3 LNG carrier is considered. Four stern models are made and tested in the CFD package, ShipFlow. No change was made to the forward hull-form. The effects of each stern on the resistance characteristics were compared. A computer program was also made based on the thin ship theory. A major hull profile parameter effecting the stern wave generation, which is the stern profile angle was varied and its effect on the wave resistance was studied. The bulb stern was also modified to change the inflow pattern into the propeller. These results were validated using a commercial CFD software package. This thesis would serve as a fore runner in the stern design of vessels in this size category. A proper understanding of the effect of stern on total ship resistance can also be studied.