Dong-Gyu Park, "An Optimization Method of Initial Principal Particulars of Small Naval Ships Considering Design Requirements", M.Sc. Thesis, Seoul National University, 2025.02.26
M.Sc. Thesis
2025.06.05 11:15
Dong-Gyu Park, "An Optimization Method of Initial Principal Particulars of Small Naval Ships Considering Design Requirements", M.Sc. Thesis, Seoul National University, 2025.02.26
조회 수 814
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| Abstract | The initial design process for naval ships involves selecting the optimal design among alternatives, during which requirements and CONOPs (CONcept of OPerations) are refined to create criteria documents like the Required Operation Capability (ROC) and Operational Requirements Document (ORD). At this stage, the initial principal particulars and weight of design alternatives are estimated using data from existing naval ships and compared to determine the optimal design. Traditionally, this process has relied on the designer’s experience, which often results in rough assessments of whether the stability, maneuverability, and criteria are met. Sometimes inappropriate specifications are estimated, resulting in delays due to optimal design changes or time needed to ensure reliability. This study proposes a method to optimize the initial specifications of naval ships according to requirements. The design variables considered are the length (L), breadth (B), depth (D), and equipment and compartment arrangements, and stability & maneuvering performance are treated as constraints. The optimization problem is formulated to minimize the lightweight (ΔL), which is an important indicator for selecting the optimal design in the initial design procedure. To estimate the weight of the newly designed naval ships, detailed weight information of the reference ship was used an empirical formula that integrated this data was used. In addition, the draft and hull form factor of the designed naval ship was calculated by applying the 3D mesh of the reference ship. Resistance was estimated using the given design parameters and the draft and hull form factor, and a propulsion system that met the required power was selected. During this process, constraints related to length, breadth, and depth arrangements, as well as propulsion system weight, were comprehensively considered to identify a propulsion system that minimizes weight. Moreover, to ensure suitability for initial design results, the design accommodated combinations of propulsion systems from at least two different manufacturers. Constraints on length, breadth, and depth were derived to enable the arrangement of equipment and compartments according to requirements. Stability & maneuvering performance were calculated to confirm compliance with the required criteria. Stability was designed to meet the U.S. Navy’s intact stability criteria under beam wind with rolling, and maneuvering performance was set to exceed the trends for small high-speed naval ships as outlined by the U.S. Navy. The formulated optimization problem was solved using the Non-dominated Sorted Genetic Algorithm-II (NSGA-II), known for its excellent convergence performance. A resulting optimization program was implemented to suggest the optimal initial principal particulars based on the hull form. This program was applied to a case study of an Unmanned Surface Vehicle (USV), which has recently seen increased design demand, comparing results for monohulls and catamarans. The study also verified whether the results were consistent with the requirements of LIG Nex 1’s Sea Sword-III by adopting the same operational requirements. The research results show that, for monohulls, the main specifications are similar to those of the Sea Sword-III, but for catamarans, the main specifications are reduced and the weight is increased. In addition, catamarans have better stability & maneuverability than monohulls. |
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| Publication Date | 2025-02-26 |
