低干舷隐身船波浪中纵向运动的模型试验及理论研究

Model testing and theoretic study of the longitudinal motions in waves of low-freeboard stealthy ship

低干舷隐身船由于采用低干舷和内倾设计,容易引起甲板上浪和非线性水动力,因而其耐波性能与传统直壁船型差别较大。文中通过模型试验和理论计算的方法,对低干舷隐身船在顶浪时规则波和不规则波中的纵向运动响应开展了研究。理论方法包括S.T.F.线性切片法和非线性时域方法,并且在时域计算中考虑了船体湿表面变化和甲板上浪对纵向运动的影响。研究表明,隐身船在波浪中的纵向运动存在明显的非线性现象,船舷内倾是导致船体纵向运动非线性的主要因素,采用非线性时域方法可以较好地预报低干舷隐身船型在波浪中的纵向运动。

The seakeeping performance of stealthy ship is different from that of traditional ship with vertical wall because of its low freeboard and tumblehome design, which can cause the ships＇ non-linear hydrodynamics and occurrence of green water on deck.In this paper, the longitudinal motions of stealthy ship in regular and irregular head waves are investigated by model testing and theoretic computation. S.T.F. method and nonlinear time domain method are included in calculation.Both the change to instantaneous wet ship surface and non-linear effects on ship motions induced by green water are included in time domain method.The experimental and numerical results show that the strong nonlinearity of the longitudinal motions is existent and the design of tumblehome is the major factor of the nonlinearity.It is proved that non-linear time domain method can predict the longitudinal motions of low-freeboard stealthy ship in waves well.