Optimization design of hull based on the computational fluid dynamics (CFD) is widely used in simulation-based design (SBD). And with the limit of computer ability, complex hull optimization such as hull appended with an actual propeller have not launched a full investigation. In this paper, we conduct design optimization of Japan Bulk Carrier (JBC) with an actual propeller (AP) based on CFD considering ship resistance and propeller wake distortion. In-house software OPTShip- SJTU is used for the present hull form optimization. Firstly, hull form modification module is applied to change the stern shape of the JBC. The in-house hydrodynamic CFD software naoe-FOAM-SJTU is applied to calculate the hull resistance and AP wake distortion. And the dynamic overset grid method is used to achieve the interaction between hull and propeller so that the optimization can take the high-fidelity flow interaction into consideration. The results demonstrate that the OPTShip-SJTU solver can be extended to optimize the coupled hydrodynamic performance in hull form optimization. The optimization results indicate a V-shaped hull can suppress the flow separation around the stern and benefit the propeller wake distortion. At the same time, the results remind us that it is necessary to consider the resistance and wake distortion together in hull optimization studies.
Hull hydrodynamic performance is an important index for ship design. For hull form optimization, it is a measure to optimization the hull hydrodynamic by modifying the shape of the hull. With the development of computational ability and the computational fluid dynamic techniques, the Simulation-Based Design (SBD) framework has been developed quickly and applied to the hydrodynamic optimization of hull form, such as the resistance, seakeeping, ship maneuver, and so on( Miao, et al., 2020; Yang, et al., 2015; Tahara, et al., 2011). Hull form optimization has four steps:
(1) the deformation of the initial hull
(2) the hydrodynamic calculation of sample hulls
(3) the surrogate model construction
(4) the best hull form searching base on the optimization algorithm:
For the resistance and wake distortion optimization, many scholars focus on the optimization of hull resistance and propeller wake distortion. In the aspect of hull resistance optimization, the single hull (Liu, et al., 2018)and the catamaran resistance ( Zha, et al.,2014). is optimized and compared with the experiment results using the naoe- FOAM-SJTU. In the aspect of propeller wake distortion optimization, the Wide Chord Tip propeller is studied and maximizes the performance of the propeller by adjusting expanded areas of the propeller blade. Results show that the propeller efficiency can be increased up to over 2% (Lee, et al., 2010). Consider the resistance and the propeller wake distortion simultaneously, many scholarship focus on the initial hull hydrodynamic performance with an actual propeller (Korkmaz, 2015; Deng, et al., 2015). The multi-objective genetic algorithm is taken as the optimization technique leading to the optimal hull forms which have better resistance and propulsion performances (Liu, et al.,2018). For closing the reality condition, the design optimization for self-propulsion of a bulk carrier hull is investigated based on the discrete adjoint method and the actuator disk method (He, et al., 2019).
