Prediction of the Seakeeping of High speed Ships

这项研究的目的是开发一种方法，从克服高速船如SES、小水线面双体船和水翼船在惊涛骇浪中的脆弱性的角度来预测和评估其耐波性。结果表明：1.(1)发展了一种新的理论来预报高速双体船体在高弗劳德数波浪中的水动力和波浪激振力。与其他复杂的计算方法相比，该理论正确地考虑了高速对水动力的影响，尽管计算负荷较小。这个理论很简单，就是将附着在主船体上的水翼的影响纳入到水动力中。(2)水池模型试验验证了理论的正确性。首先，我们发现由本理论预测的垂荡和纵摇的附加质量和阻尼系数与强迫运动试验得到的结果具有很好的相关性。利用自行研制的新的实验技术，对高速双体船的辐射和绕射产生的波浪特性进行了测量和分析。这些特性与高速船舶在波浪中的附加阻力密切相关。它们被证实与理论上的相关。(3)建立了在浅水深波浪作用下高速航行水翼所受水动力的预报理论。这可以很容易地与(1)和(2)中描述的理论相结合。2.编制了一个计算程序，可以计算和计算双体船在斜浪或短波峰中以很快的速度航行时的运动和波浪力。该程序是在海况下设计性能更好的高速船舶的有用工具。

Objective of this research is to develop a methodology to predict and evaluate seakeeping of high speed ships such as SES,SWATH and hydrofoil boats in the perspective of overcoming their vulnerability to the rough seas. The results are:1. (1) We developed a new theory to predict hydrodynamic forces and wave exciting forces on high speed ships of catamaran hull form in waves at high Froude number. This theory accounts correctly the high speed effects on the hydrodynamic forces despite light computational loads compared with other sophisticated techniques. It is straightforward with this theory to incorporate the effect of hydrofoils attached to the main hull into hydrodynamic forces. (2) Validity of the theory was confirmed by model tests in the water tank. First we found that the added mass and damping coefficients of heave and pitch predicted by the present theory are in good corelation with those obtained by forced motion test. Characteristics of waves produced by the radiation and the diffraction of high speed catamaran were measured and analyzed by new experimental technique we developed. Those characteristics are closely related to added resistance of high speed ships in waves. They were confirmed to be correlated to the theoretical. (3) We developed a theory to predict the hydrodynamic forces acting on a hydrofoil running at high speed under waves with shallow depth of submergence. This can be easily combined with the theory described in (1) and (2). 2.We completed a computer program by which we can compute and evaluate the motions and wave forces of a catamaran running in oblique or short crested waves at very fast speed. This program is a useful tool to design high speed ships with better performances in a seaway.