有限水深Kelvin源格林函数的传播特性及其应用

为探究有限水深环境下自由面兴波在远场的传播特性,应用线性水动力学的基本理论,从有限水深Kelvin源格林函数的积分表达式中提取相函数,采用同相分析法求得亚临界和超临界速度区下远场传播波系的等相线。结果表明,水深傅汝德数Fh1时远场传播波包括横波和散波两个波系,F_h1时远场波系仅由散波构成,点源兴波的影响范围可由Kelvin角的大小确定,当F_h趋近于1时Kelvin角迅速增大至90°。依据船型要素、两船相对位置和池壁几何参数,并计及船模的定常兴波经池壁反射作用后对自身和另一船模的干扰,提出了有限水深条件下并行航行两船模池壁效应的判别方法,并结合实例检查分析了某试验工况下的池壁效应。

Propagation Characteristics of Kelvin Source Green Function in Finite Depth Water and its Application

On the basis of linear hydrodynamic theory, phase function is extracted from the integral representation of 3-D Kelvin source Green function in finite depth water. By adopting stationary phase analysis method, constant phase curves and propagation wave patterns are investigated at subcritical and supercritical speed zones respectively. It indicates that far field wave systems are composed of transverse and divergent wave patterns if depth Froude number . When , only divergent wave patterns are found in the far field. The influence scope of propagating waves above can be determined by the Kelvin angle whose degree changes with depth Froude number and increases to 90 degrees near the critical depth Froude number . Based on the geometrical parameters, such as ship model particulars, relative position of two ships and tank breadth, a discriminant method is proposed for two ship models advancing parallel in calm water of finite depth, with side wall effects taken into account in towing tank. In this discrimination method, the interferences of the reflected steady waves from the tank walls, which may act on both ships, are also considered. Under the experimental conditions, the side wall effects are examined in a two-model test.