Parametric, multi-objective optimisation of ship's bow for the added resistance in waves

Abstract

For large ships, the likely sea states the ships that may encounter in their lifecycle are in the region of short length waves, compared to ships' length, where the diffraction component of the added resistance (AR) is predominant. In this paper, a multi-objective optimisation of the bow form of the standard ITTC KVLCC2 tanker was performed in terms of the AR, calm water resistance, total resistance and energy efficiency design index. The AR was estimated using semi-empirical formulas developed by the Ship Design Laboratory of NTUA. A parametric geometry model of ship's bow region and optimisation process were developed by use of the CAESES/Friendship-Framework. The conducted multi-objective optimisation procedure showed that the AR is strongly correlated to ship's waterplane area coefficient, moderately to ship's stem profile and weakly to the bow's flare angle. The optimised bow design resembles closely the LEADGE-bow hull concept, which is becoming very popular in recent full type ship new-buildings.