Prediction of the Seakeeping of High speed Ships

本研究的目的是开发一种方法来预测和评估高速船舶如SES，SWATH和水翼艇的耐浪性，以克服其对汹涌海浪的脆弱性。结果是：1。(1)建立了双体船高速船在高弗劳德数波浪中水动力和波浪激励力的预测新理论。与其他复杂的技术相比，该理论正确地解释了高速对水动力的影响，尽管计算负荷较轻。这是直截了当的理论，纳入影响的水翼附在主船体成水动力。(2)通过水箱模型试验验证了理论的有效性。首先，我们发现用该理论预测的附加质量和纵摇阻尼系数与强迫运动试验的结果有很好的相关性。采用新研制的实验技术，对高速双体船的辐射和衍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。它们被证实与理论相关。(3)我们建立了一个理论来预测在浅沉深度的波浪下高速运行的水翼所受的水动力。这可以很容易地与(1)和(2)中描述的理论结合起来。我们完成了一个计算机程序，通过它我们可以计算和评估双体船在斜峰或短峰波浪中以非常快的速度运行的运动和波浪力。该程序是设计具有较好性能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.