23 造波抵抗と砕波の低減を目的とした船型改良法に関する研究 : 実数値遺伝的アルゴリズムを用いた多目的船型最適化

概要

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Ships with underwater acoustic equipments are required to have high propulsive performance and low noise. This requirement means, from view point of wave-making characteristics, these kinds of ships need hull form with low wave-making resistance and small wave-breaking. In general, the operation speeds between cruising and observing are different. In other words, it is necessary to improve different wave-making characteristics at two different speeds. The present paper proposes a hull optimization method for reducing wave-making resistance and wave-breaking, using the real-coded genetic algorithms. The real-coded genetic algorithm of the optimization method, employs a crossover operator for combining of the methods called LUNDX-m (UNDX on m Latent Variables) and EDX (Extrapolation-Directed Crossover), and employs POSS (Pareto Optimal Selection Strategy) as a generation-alternation model. The panel-shift type Rankine source method is used for the calculation of wave-making resistance as the first objective function. The gradient of calculated wave-height is used as the second objective function for an indicator of wave-breaking. The hull optimization for DTMB Model 5415 is carried out using the program which is based on the present method. In the optimization, many Pareto solutions are obtained. It is confirmed that these hull forms have low wave-making resistance and small wave-breaking comparing with the original form, by the Rankine source method.