船舶碎冰区横荡运动的水动力导数研究

Research on hydrodynamic derivatives of ship’s sway in floe ice region

目前敞水水动力导数的研究较为成熟,针对冰水耦合后的船舶水动力导数研究尚处于起步阶段。本文使用STAR-CCM+软件中DEM颗粒模拟碎冰粒子,求解碎冰区冰水混合介质中船舶横荡运动水动力导数。通过开启DEM模块下双向耦合模式,进行动量、能量交换达到冰块与水耦合作用。选取低频频率f分别为0.06 Hz、0.08 Hz、0.1 Hz、0.12 Hz、0.14 Hz进行横荡运动数值模拟,忽略自由液面的影响,分别计算敞水工况以及碎冰工况下船舶各运动频率下所受的侧向力以及转艏力矩,并通过对各频率下无因次后的力以及力矩拟合来解出部分水动力导数。通过计算得知,敞水工况下船舶各部分水动力导数值与统计公式计算值相差不大,冰水耦合后大部分水动力导数在低频率下明显大于敞水工况下的水动力导数,而水动力导数Yv’值比敞水工况值小。

The research on the hydrodynamic derivative of open water is relatively mature, but the research on the hydrodynamic derivative of ice-water coupling is still in infancy. In this paper, DEM particles in the CFD software STAR-CCM+ were used to simulate floe ice to solve hydrodynamic derivatives of the ship’s sway under ice-water coupling condition. The momentum and energy exchange were performed to achieve the coupling effect between ice and water by turning on the two-way coupling mode under the DEM module.In this paper, the low frequency f was selected to be 0.06 Hz, 0.08 Hz, 0.1 Hz, 0.12 Hz and 0.14 Hz for numerical simulation of sway. Ignoring the influence of the free liquid surface, the lateral forces and turning moments of the ship at each frequency of motion under open water condition and floe ice condition were calculated. Partial hydrodynamic derivatives were calculated by fitting dimensionless forces and moments at each frequency. Through calculation, it is known that hydrodynamic derivatives of the ship under open water condition are not significantly different from hydrodynamic derivatives calculated by the statistical model. Most of hydrodynamic derivatives under ice-water coupling condition are significantly larger than those under open water condition at low frequencies, the value of hydrodynamic derivative Yv’ is smaller than that under open water condition.