Prediction of Effects of Hull Forms on Seakeeping Qualities of Ships

本研究的目的是建立一个系统的方法来预测波浪中的附加阻力和船舶在甲板润湿影响下的安全性。这种系统的方法将有助于从船体的耐波性来评价船体形状。有几种可用的方法不一定能达到这个目的。他们没有给出准确的预测，正确地反映了船体形状之间的一点差异的影响。因此，我们需要开发新的方法，特别是在甲板上的水的影响下，增加阻力和瞬态运动导致倾覆，因为这些还没有得到充分的研究。我们在本研究中所做的工作如下：1。为了清楚地说明船首形状对船舶在波浪中行驶时产生的非定常波型的影响，我们给出了几个实验数据。我们提出了一种新的理论方法来描述这种效应，该方法大大提高了弓形钝时附加阻力预测的准确性。2. 研究了一种考虑有限量级运动效应的水动力计算方法。3. 我们成功地提供了海水进入舷墙甲板时倾覆的计算机模拟。该仿真程序使我们能够评估舷墙高度对船舶安全性的影响。4. 采用精确满足船体表面边界条件的三维面板法，对斜浪和顺浪附加阻力进行了预测。通过对计算技术的改进，该方法可以从附加阻力的角度对有细微差别的船体形式进行评估。

Objective of this study is to develop a systematic method for predicting added resistance in waves and safety of a ship under the effects of deck wetting. Such systematic method will be useful for evaluating hull form from its seakeeping qualities. Several methods available do not necessarily serve this purpose. They do not give accurate prediction which reflect correctly the effects of a little difference between hull forms. So we need to develop new methods particularly for added resistance and transient motions leading to capsize under the influence of water on deck, since those have not been fully investigated so far.What we have done in this study are as follows: 1. We presented several experimental data to show clearly bow shape's effect on the unsteady wave pattern generated by a ship running in waves. This effect was described by a new thoretical approach we developed, accuracy of prediction of added resistance when bow shape is blunt is improved considerably by this new method. 2. A simple method was investigated for computing hydrodynamic forces with the finite magnitude effects of motion taken into consideration. 3. We succeeded in providing computer simulation of capsizing when sea water is coming onto deck over bulwark. This simulation program enables us to evaluate the height of bulwark on the safety of ships. 4. 3D panel method in which the boundary condition on the hull surface is accurately satisfied was applied for predicting added resistance even in oblique and following waves. With some improvements in computational technique, this method is useful for eavaluating hull forms with a little difference from the standpoint of added resistance.