尺度效应对船舶在受限水域航行时的流场偏移影响研究

Study on effect of scale effect on flow field migration of ships advancing through confined waters

为了更好地分析船舶在限制水域的流场特性,有必要对实尺度船舶进行数值模拟研究。该文以国际标准集装箱船KCS为研究对象,基于RANS方程数值求解的方法,对浅水、近岸壁且低速航行的船模与实尺度船进行数值仿真分析,其中船模的缩尺比为λ=31.6。首先通过KCS深水阻力计算结果与试验进行对比,验证了网格划分的合理性和数值计算的准确性。然后通过求解船模与实尺度船在不同水深和船-岸距离的工况,得出并对比不同缩尺比下船体表面压力、周围流场以及船舶尾部和桨盘面处的伴流分数变化情况。结果表明:水深和船-岸距离的减小会导致船体尾部伴流分数与流场偏移;船舶在实尺度情况下受高雷诺数的影响,其高伴流区域、流场偏移及桨盘面周上伴流分数分布均小于模型尺度,这会对桨盘面处进流产生影响,从而影响船舶的操纵性与快速性。

In order to better analyze the flow field characteristics of ships in restricted waters, it is necessary to study the numerical simulation of real-scale ships. Taking the international standard container ship KCS as the research object, based on the numerical solution method of RANS equation, the numerical simulation of the hydrodynamic characteristics of the model-scale ship(the model-scale ratio λ=31.6) and full-scale ship advancing through restricted waters at low speed is carried out. Firstly, the rationality of mesh generation and the feasibility of numerical calculation are verified by comparing the calculated value with the experimental value for KCS advancing through deep water. By solving the working conditions of ship model and full-scale ship in different water depth and offshore distance, the surface pressure of ship, the surrounding flow field, the wake fraction at the stern and propeller disk surface under different scale ratios are obtained and compared. The results show that the decrease of water depth and ship shore distance will lead to the deviation of wake fraction and flow field at the stern of the ship. Under the influence of high Reynolds number, the high wake region, flow field offset and wake fraction distribution around the propeller disk of full-scale ship are smaller than the model scale ship, this will affect the inflow at the propeller disk, thus affecting the maneuverability and rapidity of the ship.