比降河道内船舶航行特性及尺度效应分析

Analysis on Ship Navigation Characteristics and Scale Effect in Slope River Channel

长江航道水面比降对船舶水动力性能有着直接影响,为探究不同尺度船舶在比降水域的水动力特性区别,以KCS集装箱船为对象,借助计算流体力学(CFD)软件Star-CCM+求解RANS方程,结合流体体积(VOF)方法对比降水域船舶航行进行数值模拟,并从船舶阻力、姿态、艉部伴流和自由液面等方面对船舶尺度效应进行分析。结果表明:由于船舶纵倾角度普遍大于水面比降,数值计算所得比降阻力大于经验公式计算结果;模型尺度航行阻力中摩擦阻力占比大于实船,压阻力占比随比降增大而增大;模型尺度尾部轴向伴流区大于实船,伴流区随水面比降增大而收缩,螺旋桨推力减小,船舶沿水面坡度上行难度增大。研究结论对船舶沿水面坡度航行决策有指导意义。

The water surface slope of the Yangtze River channel has a direct impact on the hydrodynamic performance of ships.In order to explore the difference in hydrodynamic characteristics of ships with different scales in the slope waters,taking the KCS container ship as object,the RANS equations are solved by computational fluid dynamics(CFD)software Star-CCM+,combining the volume of fluid(VOF)method,the ship navigation in the slope waters is simulated,and the ship scale effect from the aspects of ship resistance,motion attitude,wake,and free surface are analyzed.The results show that since the trim angle of the ship is generally greater than the angle of water surface slopes,the gradient resistance calculated by the numerical calculation is greater than that calculated by the empirical formula.The proportion of friction resistance in the navigation resistance of the model scale ship is greater than that of the real scale ship,and the proportion of pressure resistance increases with the increase of the water surface slope.The axial wake region of the stern of the model scale ship is larger than that of the real scale ship.The wake region shrinks with the increase of the water surface slope,the propeller thrust decreases,and the difficulty of the ship ascending along the water surface slope increases.The research conclusions have guiding significance for the decision-making of ships sailing along the slope of the water surface.