Multi-objective Optimization For The EEDI And Seakeeping Ability Of A Containership In Seaway

The Maritime Environment Protection Committee has proposed regulations such as "Guidelines on the Method of Calculation of the Attained Energy Efficiency Design Index(EEDI)for New Ships" and "Guidelines for voluntary use of Energy Efficiency Operational Indicators(EEOI)" in recent years.Consequently,increasing attention is paid to the energy-saving and emission-reduction during the ship operation and knowledged high performance ship design inside the ship industry.This paper proposed a comprehensive numerical calculation method to evaluate the resistance performance and seakeeping performance in seaway.The 3100 TEU containership was chosen as an object and the friction resistance,wave-making resistance and viscous pressure resistance was evaluated respectively based on Reynolds averaged Navier-Stokes equation with k-epsilon turbulence model,Rankine source method with the potential theory with and the boundary layer momentum integration method.Besides,the 6 DOF motion response,second order drift force and seakeeping ability indexes at actual sea were obtained by using 3D panel method and long term forecast theory.In order to account for the wind and wave resistance increase in sea way,the infinite volume method and a physical component model were adopted to calculate the wind resistance.And the results were verified by a series of open wind tests.The second order drift force based on the direct pressure integration was regarded as wave added resistance.Thus the total resistance in seaway and speed loss coefficient could be properly estimated.Furthermore,a multi-objective hydrodynamic performance optimization system considering energy efficiency design index EEDI,ship motion response and seakeeping ability in seaway was built based on the engineering assistant software,Isight.A radial base function was used in parametric modeling and hull form transformation and NSGA-II was used for the optimization loop.In addition,the actual navigation route and the propeller characteristics was taken into consideration in this system for overall performance estimation.The results suggest that the multiple hydrodynamic performances of a containership can be optimized at the same time by using hull form transformation and container layouts reconfiguration.And this method provides valuable reference to containership design and hydrodynamic performance optimization.