基于浮冰区参数化设计的船舶冰阻力数值模拟

Numerical Simulation of Ship Ice Resistance Based on Parametric Design of Floe Ice Field

本文参照真实冰区环境下浮冰尺度(MCD)概率分布规律,基于遗传算法运算器Glapagos,采用Grasshopper参数设计工具对Voronoi图进行全局优化,建立了符合自然环境的浮冰区模型,采用LS-DYNA流固耦合方法对船舶在浮冰区航行的参数影响情况进行了研究。研究发现:船肩附近的浮冰滑移现象最为显著,船艏附近的浮冰破碎现象则更为明显;船体受浮冰的冲击频率随浮冰密集度的提高呈明显增大趋势,而受冰厚影响较小;浮冰载荷波动的剧烈程度与影响因素(浮冰密集度、浮冰厚度和航速)正相关;相比大尺度浮冰,小尺度浮冰具有较高频率的冲击载荷、较大的载荷脉冲宽度和成分占比更高的摩擦阻力,这对浮冰阻力起到了明显的加强作用;浮冰阻力具有一定的随机性,但一般随浮冰密集度、冰厚和航速的增加而增加。

With reference to the probability distribution law of floe ice’s MCD(Mean Calliper Diameter)in real floe ice areas,Grasshopper parametric design tool is used to optimize Voronoi diagram globally based on genetic algorithmoperator Galapagos.A model which is close to the floe ice in the natural environment is established.LS-DYNA fluid-structure interactions method(FSI)is used to simulate the parameter influence of ship’s floe ice resistance.It is found that the phenomenon of floe ice drifting near the ship shoulder is most significant while the phenomenon of floe ice breaking near the bow is even more apparent.The frequency of ice loads that ship hull affected by floe ice increases significantly with the increase of the density of floe ice,but it is less affected by the thickness of floe ice.There is a positive correlation between the fluctuation intensity of floe ice load and some influencing parameters(floe ice concentration,thickness and ship velocity).The floe ice resistance presents a certain randomness,and yet increases generally with the increase of ice density,ice thickness and ship velocity.