Parametric Design Method And Program Realization Of Bulbous Bow

Ship lines design is an extremely complex and important element in ship general design. Ship's structural design, performance calculations, arrangements of the cabin, and production layout are all based on lines design. The efficiency of lines design also have a direct impact on the entire cycle of ship design and construction. The lines design of the bulbous bow is a important and difficult point in the ship lines design, because of its space complex shape has many kinds,therefore,it's difficult to summarize a set of specific methods for general applications. Usually, design a bulbous bow is dead against the idiographic ship type characteristics, ascertain one or more bulbous bow schemes according to some basic laws and experiences, and finally ascertain it through repeated model tests to improve the shape of the bulbous bow. Therefore, the process of bulbous bow' design is very complex,often need to be amended, and the efficiency is not high. So how to create ship bulbous bow quickly is still an important problem for a designer to solve.In this paper,a 3-D boundary design method of bulbous bow is adopted which we can control the surface shape of the bulbous bow through its 3-D characteristics boundary lines. These characteristics boundary lines include:longitudinal boundary line, transverse boundary line and the transverse line of bulbous bow in forward perpendicular. The shape of the boundary lines can be controled by the feature points and vector modulus length. Extraction point and vector modulus length as parameters, when the parameters are selected you can control 3-D characteristics boundary lines of bulbous bow.3-D boundary lines can further drive the suface of bulbous bow to create. For smoothing transition from bulbous bow to hull, we can guide transition surface to create through defining the resecting trace lines and the maximum width lines of the transition surface of bulbous bow.Use CATIA as the exploitation platform and VB as the exploitation tools,use the secondary exploitation technology of the platform, and use the bulbous bow's composing and surface transition method refered above to compile the parameterize design program of bulbous bow. The program includes two main modules:one is the parameterize creation of the bulbous bow's main body,the other is bulbous bow's smoothing transition to the main hull. In this program, through controlling the view's operation to achieve real-time observation the 3-D characteristics boundary line of the bulbous bow's main body,which can be observe and modify by the designer to meet the design requirements.In the paper , take 23,000 bulk carrier as an example, use this approach to fit the bulbous bow's main body of the real ship,and find out that the the results is inosculated basically by comparing the body lines of the designed bulbous and the real ship,by which we can inspect the method's suitability. Through designing to install the bulbous bow to 3500t multipurpose vessels,use this method to design the bulbous bow's main body and control its transitional surface. By observing the 2D body plan and half breadth water lines plan from this 3-D model, prove that use this method to generate bulbous bow and transitional surface can basically meet the needs of the smoothing,and validate that use this method to design a bulbous bow is feasible.