Research On Hull Form Optimization Design Methodology For The Container Vessel Considering Slow Steaming

With the development of the global shipping industry,the consideration on fuel consumption from the standpoint of ships operating and the concerning of the greenhouse gas emissions form marine environmentalists have caused widespread attention throughout the world.Hull form optimization that makes contribution to energy-saving and emission-reduction in order to realize the benefit maximization between ship economy and environmental protection will be the key research topic in the field of ship scientific today.Aiming at the international forefront of the ship technology development,the paper innovatively proposes a new type of hull form optimization design concept.It mainly involves three aspects which are the breakthrough on the hull geometry transformation technology,the uses of reliable and efficient ship hydrodynamic performance prediction techniques and the technical support from the optimization theory.Ultimately a robust ship optimal design system has been constructed and undertaken the real engineering application,which will lay the foundation for the independent innovation of design methodology and the rapid development of technical capacity henceforward.The paper begins with summarizing the ship optimization research production at domestic and abroad,and then discusses in detail on three core technique modules mentioned above respectively and points out the development trend of ship optimization technology.On the first place,the partially parametric mapping deformation method is presented via the features parametric curve.Accordingly the deformation theory formula has been originally put forward which is applicable to launch the three-dimensional partial parametric hull deformation and geometry smoothing transition,proving this technology correctness and reliability in result.Secondly,the ship resistance performance is numerical solved by the use of Rankine source panel method.Meanwhile,the motion characteristics of the ship sailing in waves have also taken account.Based on strip theory assumptions,the theoretical prediction of movement performance is completed by dint of the well-known STF method.The ship hydrodynamic performance prediction techniques play a significant role for precise evaluation of objective functions in optimal system.Again,the traditional and intelligent optimization algorithm have been elaborated which centers upon basic principles,processes,and improved strategies et cetera.After that,we commence related research on multi-objective optimization theory,including multi-objective genetic as well as particle swarm optimization algorithms and multi-objective linear programming thought.Based on the three key technologies,the hull form optimal design system has been established,which is equipped for important directive significance for in-depth understanding the connotation of hull form optimization and the establishment of design process.Subsequently,take the high-speed ship as the research object,an example of the hull mid-front part form optimization considering single design speed ground on different optimization algorithms for the ship S60 is illustrated.The results show that there is remarkable decrease of ship resistance.The difference of drag reduction and the calculation convergence between various optimization algorithms has also made comparative analysis.Meantime,the multi-objective genetic algorithm is adopted for the conduction of the ship DTMB5415 bulb form optimization with the consideration of multi-speeds.As a result,the Pareto set of each sub-objective function is obtained,where the optimized hull show all resistance reductions at different calculational speeds.The optimal result is so preferable that demonstrates the feasibility and effectiveness of the ship optimization design system established in this study.Further,considering the international standard KCS container ship,the total resistance is calculated by the potential flow theory and the empirical formula which agrees well with the corresponding experimental data and furtherly acquires validation with the overall error of 2.0%.Accordingly the ship forepart and stern form has been optimized under conditions of the single design speed and all speeds range based on the considerations of generally distributed and variable operational speeds for the operating characteristics of modern container ships synchronously.The optimized result presents well-balanced drag reduction benefits which averagely remain above 4.0% of ship resistance decrease.Eventually,we bring forth scenario analysis based hull form optimization design methodology innovatively.A large container vessel 9200 TEU is selected for bulbous bow form optimization considering multiple operational conditions due to the new operating measure of slow steaming for modern container vessels.Combining with the operational profile provided by the ship-owner,the ship bulbous bow form is optimized for the purpose of total profits on resistance reduction under multiple operational conditions by employing the multi-objective linear programming thought,where the optimal decision have achieved a decrease of 2.845% in the total conditions resistances.Based on the ponderation of ship resistance,movement performance in seaway has also taken account.Through introducing the statistical data of seaway condition at Far East to North America Atlantic coast route,we set up another objective function on ship movement performance considering multiple operational conditions by continuing to reference the operational profile and to use the multi-objective linear programming methodology.Therefore the multi-objective of resistance and movement performance based hull form optimization design system is successfully established.The study is of great engineering significance for the issue on energy-saving and emission-reduction throughout the actual operating of modern container vessels,which also provide advanced research tools and reliable technical supports for the innovative design of hulls and the research and development of green ship.