Otimização das formas de cascos de deslocamento em relação a sua resistência ao avanço. / Displacement hull optimization regarding to ship wave resistance.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Due to an increasing necessity of building new vessels, whether by new orders or fleet renewal, the development of computational programs that could allow optimization of hull shapes is always helpful, saving project time and ensuring better performance at sea. Thus, the development of a synthesis procedure that allows obtaining shapes with better performance adds value to the initial phase of the ship geometry concept. The work to be presented herein objectives the presentation of a methodology to achieve optimal shapes for displacement hulls in relation to the total resistance, starting from an initial geometry given, describing hull form and applying specific constraints to optimization problem with the purpose of guarantee a reliable solution. Therefore, inside this optimization process there are included some constraints that ensure a feasible final solution, as maximum variation of ship length, total volume and stability. Hull geometry is described by using B-Spline surface functions and the ship wave resistance is calculated using Michells formulation as a first approximation of the total resistance for high Froude numbers. Once vessel surface is well defined, B-Spline parameters are varied until an optimal form is attained and the minimum resistance is achieved. It can take a little time to calculate, depending on ship definition (number of buttocks and waterlines) and the problem complexity (number of constraints and variables). Ship displacement and other hydrostatic properties as stability, given by transversal KM , wetted surface, used for calculating ship resistance, can be obtained using the vectorial calculus. This work has been developed using C++ language, except the optimization process which makes use of a MATLAB® function called fmincon. This study has been held at the Department of Naval and Ocean Engineering of the University of São Paulo, Brazil.

ASSUNTO(S)

b-splines petroleiros (projeto) superfícies de resposta (otimização) ship resistance resistência de navios optimization displacement hull casco de embarcações (projeto)

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