Development of Ship Hull Optimization Method Based on Computational Fluid Dynamics

本课题的研究目标是发展基于计算流体力学的船体优化方法。在两年的研究项目中，发展了数值方法，并将其应用于改进AFT。没有船尾灯泡的油轮的一部分。本文对船尾形状进行了改进，减小了船尾的粘性阻力，增加了轮盘顶部螺旋桨的进气量，从而降低了船尾振动。该数值方法包括求解船舶粘性流场的雷诺平均Navier-Stokes方程方法、表达尾部修正函数的二维B样条函数、利用局部线性化解的迭代优化方法和加权平均的标量多目标函数。数值结果表明，只要粘性阻力最小，船尾形状就会修改为具有特征的V型框线。另一方面，如果只增加轮盘顶部的螺旋桨进气量，就会出现尾球框线，而如果减小粘性阻力，增加螺旋桨轮盘顶部的进气量，则可以得到上述组合型框线。这些结果与在循环水流道中获得的实验数据吻合得很好。

The objective of present research project is development of ship hull optimization method based on Computational Fluid Dynamics. In the two year research project, the numerical method has been developed and applied to improve aft. part of tanker ship without a stern bulb. In this study, stern shape was modified so as to decrease the viscous resistance and increase the propeller inflow at the top of the disc, which results in lowered stern vibration. The present numerical approach includes the Reynolds-averaged Navier-Stokes Equation method to solve viscous flow fields around a ship, the two-dimensional B-spline function to express stern-modification function, the iterative optimization procedure utilizing locally linearized solutions, and the scalar multi-objective function with weight averaging. The numerical results show that the stern form is modified to have characterized V-type frame line if only viscous resistance is minimized. On the hand, the stern-bulb type frame line appears if only propeller inflow at the top of the disc is increased, furthermore, combined type of frame line of above-mentioned was obtained if viscous resistance is minimized and inflow at the top of propeller disc is increased. These results agree well with the experimental data, which had been obtain in circulation water channel.