Ship Hull Generation And Sea Keeping Performance Optimization Research Based On ISIGHT

At present, optimization, as an important measure to improve performance of ships, is more and more adopted in engineering by designers. In order to change the performance of ships, an obvious measure is to control the factors that might influence performance. For instance, the factors that affect ship resistance mainly include length (L), width (B), draft (T), prismatic coefficient (Cp), longitudinal center of buoyancy (lcb), midship coefficient (Cm), and so on. As a special ship, the designer of tuna seiner ship must learn about the factors that might affect ship seakindliness in the beginning of engineering, so as to select proper parameters during engineering and make necessary improvement to existing parameters during performance optimization for fishing ships with better seakindliness.However, calculation to single type of ship can only serve as performance evaluation and examination. There is no comparability, and meanwhile tests consume considerable labor, equipment and expense. In order to figure out the influence of ship parameters to seakindliness, systematic calculation on series of ship types is necessary, so as to identify ship movements and loads in different parameters, and compare one another to provide effective reference for designers. In view of the above stated, the author established a ship optimization system, using ISIHGT, a multi-discipline optimization software platform. The system optimizes ship to satisfy certain requirements by changing certain parameters and keeping other parameters almost unchanged, and then set certain parameters as targets. This system is mainly consistent of tow modules. The first is a ship form change program, which generates series of ship forms by controlling parameters. The second is an interpolation system of seakindliness calculation results, based on WASIM. The interpolation system takes ship vertical movement indexes as target, such as pitch angle, calculate the series of ship forms generated, and search for the best one.In this thesis, the author established a ship form change program based on iSIGHT platform, and by controlling series of parameters, series of ship forms with different fineness coefficient and different breadth-draft ratio are generated from original ship form. Then, detailed calculation to vertical movement of tuna seiner ship was conducted, and figures were drawn. By analysis, the influence of main ship dimension and ship factors to vertical movement of tuna seiner ship in waves was concluded. And further, according to the figures drawn, an interpolation program was developed. Together with the ship form change program, the two programs form a complete set of optimization system to search for ship forms that have most favorable pitch angle, head vertical acceleration, strike situation and roll angle, and the tuna seiner ship form with the best stability in movement in waves was found out.