Optimizing The Bow Shape Of A Large Tanker Ship

Seaborne transport is considered one of the most efficient modes of transport. However, with increasing environmental awareness and with an anticipated structured regulation on carbon emissions the shipping industry by all means available will be required to reduce its environmental impact. The IMO has set out its own regulation for reducing shipping carbon emissions by 30% by the year 2030 and hence all new ships will adopt (Energy Efficiency Design Index) EEDI and a ship Energy Efficiency Management plan ("SEEMP") for the ships in operation.Bulbous bow retrofitting is one of the solutions for "SEEMP" Ship energy efficiency management plan for ships in operation. With a projected increase in oil prices and introduction of heavy taxes on carbon emissions, there is an urgent need to re-designing the ships in operation by retrofitting some specific parts like the bulbous bow and energy saving devices in order to reduce the resistance of the hull, and hence increase the efficiency.This paper focuses on the optimization of hull lines by utilizing delta shift functions in order to reduce the hull resistance. The optimization method employed in this paper uses CAE platform of friendship-framework integrated with the viscous flow (CFD) solver Shipflow, this simulation-driven design can be employed to alter a series of geometric variations of the hull shape using a wide range of design variables in order to reduce the resistance. The validity of this research will be exhibited with results from the case study of a KVLCC2 tanker ship.While the bulbous bow optimization demonstrates its viability throughout this report,the wetted surface area may increase which in turn leads to increased viscous resistance, but from the reduction of total resistance, the optimization strategy employed is regarded as a success. Based on this investigation, the optimization of the hull lines of KVLCC2 tanker ship is a good reference strategy for similar ships.In order to optimize the hull lines and reduce the resistance, three optimization stages are employed. (i) The aft-body part of the initial hull is modified to generate an optimal new hull (ii) A bulbous bow is parametrically designed and later attached to the new hull(from stage i).It is then optimized to generate a new optimized bulbous bow hull. (iii) The tangent search design engine (TSearch) is considered as the last stage as it creates a longitudinal shift of the offsets according to b-spline curve whose vertices are controlled by an optimization algorithm as described in Chapter 7, achieving retrofitting objective. Optimization computation is run and the results clearly shows a significant reduction of 2.43% of total resistance and the wave patterns demonstrate that the diverging waves have been reduced significantly.